BR112015032203B1 - METHOD FOR THE PREPARATION OF (1,2,4)-TRIAZOLE(4,3-A) PYRIDIINES - Google Patents

Abstract

METHOD FOR THE PREPARATION OF (1,2,4)-TRIAZOLE(4,3-A) PYRIDIINES Disclosed herein are methods for the preparation of [1,2,4]triazol[4,3-a]pyridines, particularly (R )-6-(1-(8-fluoro- 6-(1-methyl4H-pyrazol-4-yl)-[1,2,4]triazol[4,3- a]pyridin-3-yl)ethyl)- 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one, and precursors thereof.

Description

Cross reference to related request

[001] The benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Serial No. 61/838,856 filed June 24, 2013, is claimed here, and its disclosure is incorporated herein by reference.

Background of the invention Field of invention

[002] The present disclosure relates to methods and processes for the preparation of [1,2,4]triazol[4,3-a]pyridines, including those useful as cancer treatment agents and compositions, and for the preparation of precursors of these. Disclosure includes stereospecific methods and processes.

Related Technology Description

[003] Some [1,2,4]triazol[4,3-a]pyridines are useful in the treatment of diseases such as cancer, in particular, gastric, esophageal, NSCLC, melanoma and pancreatic cancer.

[004] PCT publications WO 08/008539 and WO 09/091374, each incorporated herein by reference, describe triazolpyridines and some processes for preparing them.

Summary of the invention

[005] One aspect of the disclosure is a reaction method of (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-( 3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl)propanehydrazide (“HYDZ”): under conditions sufficient to form (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-a] pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“A”):

[006] Optionally, the reaction comprises contacting HYDZ with a thiophosphetan compound. Alternatively, the reaction optionally comprises contacting HYDZ with a phosphorus (V) dehydrating agent. When the reaction comprises the contact of HYDZ with a dehydrating agent, the reaction can optionally be carried out in the presence of a base. Furthermore, compound A may optionally contact an acid under conditions sufficient to form a salt of compound A. Alternatively, compound A may optionally contact a water-rich solvent having a pH of at least 7 under sufficient conditions. to form the monohydrate form of compound A.

[007] Another aspect of the disclosure is a method of forming HYDZ by reaction of (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl) acid propanoic (“NAPA”): 3-fluoro-2-hydrazinyl-5-(1-methyl-7H-pyrazol-4-yl)pyridine (“PIRH”): and a binding reagent, and under conditions sufficient to form HYDZ: NAPA may be a salt including, for example, HCl, HBr, sulfonic acid, diisopropylamine, or potassium.

[008] Yet another aspect of the disclosure is a method of forming NAPA by mixing 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“ΝΑΡΗ”): and a basis, under conditions sufficient to form NAPA: wherein R1 is Br, Cl, I or OTf and R2 is COOH or C1-3 alkyl ester, and when R2 is C1-3 alkyl ester the method of forming NAPA also comprises hydrolysis of the C1-3 alkyl ester to form a acid.

[009] A related aspect of the disclosure is a method of forming NAPH by (i) mixing a methylnicotinate of Formula (I): wherein R3 is Cl, Br, or I, and R4 is alkyl with 1,3,5-triazine, and a base, under conditions sufficient to form a naphthyridinone of Formula (II): (ii) mixing the naphthyridinone of Formula (II) with methoxyethanol, a base, and a copper catalyst (I), under conditions sufficient to form NAPH:

[010] In yet another related aspect, the disclosure is directed to a method of forming NAPH by (i) mixing protected N-(3-formyl-4-amino-2-alkoxy)pyridine: where PG is a protecting group and R8 is alkyl, with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: and base, under conditions sufficient to form a naphthyridine of Formula (III): (ii) acidification of naphthyridine of Formula (III), under conditions sufficient to form NAPH:

[011] Yet another aspect of the disclosure is a method that includes (i) mixing 4-amino-2-alkoxypyridine: wherein R8 is an alkyl group, with a pivaloyl compound of Formula (IV): where R5 is Cl, Br or OC(O)alkyl, and base, under conditions sufficient to form N-(2-alkoxypyridin-4-yl)pivalamide: (iii) mixing N-(2-alkoxypyridin-4-yl)pivalamide with a lithium reagent, under conditions sufficient to form the protected N-(3-formyl-4-amino-2-alkoxy)pyridine: (iv) ) mixture of protected N-(3-formyl-4-amino-2-alkoxy)pyridine with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: and base, under conditions sufficient to form a naphthyridine of Formula (III): (v) ) acidification of naphthyridine of Formula (III), under conditions sufficient to form 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“NAPH”):

[012] Yet another aspect of the disclosure is a method that includes (i) mixing 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“NAPH”): and a basis, under conditions sufficient to form NAPA: wherein R1 is Br, Cl, I or OTf, and R2 is COOH or C1-3 alkyl ester, and when R2 is C1-3 alkyl ester the method of forming NAPA also comprises hydrolysis of the C1-3 alkyl ester to form an acid; (ii) mixture of NAPA with 3-fluoro-2-hydrazinyl-5-(1-methyl-7H-pyrazol-4-yl)pyridine (“PIRH”): and a coupling reagent, and under conditions sufficient to form (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-(3 -(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl)propanehydrazide (“HYDZ”): (iii) reaction of HYDZ under conditions sufficient to form (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)- [1,2,4]triazol[ 4,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“A”):

[013] Additional aspects and advantages will be apparent to those of ordinary skill in the art from a review of the detailed description below. Although the methods disclosed herein are susceptible to embodiments in various forms, the following description includes specific embodiments with the understanding that the disclosure is illustrative, and is not intended to limit the invention to the specific embodiments described herein. For the compositions and methods described herein, optional features, including, without limitation, components, composition ranges thereof, substituents, conditions, and steps, are contemplated to be selected from various aspects, embodiments, and examples provided herein.

DETAILED DESCRIPTION OF THE INVENTION

[014] Disclosed here is the preparation of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4, 3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (Compound A), or a salt thereof (e.g., the HCl salt ): and its monohydrate form:

[015] Compound A is advantageously prepared through the convergent synthesis of three active pharmaceutical ingredient (API) starting materials: 3-(2-methoxyethoxy)- 1,6-naphthyridin-5(6H)-one (“NAPH” ), 3-fluoro-2-hydrazinyl-5- (1-methyl-7H-pyrazol-4-yl)pyridine (“PIRH”), and an S-propionic acid or ester. where R1 is Br, Cl, or I, and R2 is COOH or C1-3 alkyl ester

[016] The general scheme for preparing Compound A is shown below. The optical purity of Compound A is controlled during the synthetic process by the quality of the input starting materials and the specific reagents used for the transformations. Chiral purity is preserved during the ligation reaction (the second step) and the dehydration reaction (the third step).

[017] The method of preparing Compound A that is disclosed here advantageously results in a robust, scalable and efficient process.

DEFINITIONS

[018] Compounds can be identified by their chemical structure and/or chemical name. When chemical structure and chemical name conflict, chemical structure is determinative of the compound's identity. The compounds described herein may contain one or more chiral centers and/or double bonds and therefore may exist as stereoisomers, as double bond isomers (i.e., geometric isomers), enantiomers or diastereomers. Therefore, any chemical structures within the scope of the specification shown, in whole or in part, with a relative configuration encompass all possible enantiomers and stereoisomers of the illustrated compounds including the stereoisomerically pure form (e.g., geometrically pure, enantiomerically pure or diastereomerically pure) and enantiomeric and stereoisomeric mixtures. Enantiomeric and stereoisomeric mixtures can be evolved into their enantiomeric or stereoisomeric components using separation techniques or chiral synthesis techniques well known to the qualified professional.

[019] For the purposes of the present disclosure, “chiral compounds” are compounds that have at least one center of chirality (i.e., at least one asymmetric atom, in particular at least one asymmetric C atom), which has an axis of chirality, a chirality plane or a screw structure.

[020] It is believed that the chemical formulas and names used herein correctly and accurately reflect the underlying chemical compounds. The present disclosure, however, provides more than the particular compounds, methods, or modalities used by way of illustration. Therefore, it is understood that the formulas used herein, as well as the chemical names assigned to the correspondingly indicated compounds, illustrate embodiments and do not necessarily limit what is provided by the disclosure to any specific tautomeric form or to any specific optical or geometric isomer, unless that specifically determined.

[021] Unless otherwise indicated, terms and abbreviations in this specification include the normal and common meaning for those in the relevant field.

[022] Particular abbreviations, as used in the specification, correspond to the unit of measurement, techniques, properties, or compounds as follows: DIPEA diisopropylethylamine DMAC N,N-dimethylacetamide h hour(s) HCl hydrochloric acid H2O water HSO3 bisulfite IPA alcohol isopropyl Kg and/or kg kilogram K2CO3 potassium carbonate L and/or l liter MeTHF 2-methyl tetrahydrofuran M molar MeCN acetonitrile MeOH methanol Min and/or min minutes ml milliliter(s) mM millimolar mmol millimol(s) N2 nitrogen NaHCO3 bicarbonate sodium Na2CO3 sodium carbonate OTf Trifluoromethanesulfonate (triflate) RT and/or rt room temperature THF tetrahydrofuran Mm micrometer (s)

[023] When the term “alkyl” covers linear or branched radicals that have one to about twelve carbon atoms. Alkyl radicals include “lower alkyl” radicals that have one to about six carbon atoms. Examples of such radicals include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isoamyl, hexyl and the like. Also included are lower alkyl radicals that have one or two carbon atoms. The term Cn means that the alkyl group has “n” carbon atoms. For example, C4 alkyl refers to an alkyl group that has 4 carbon atoms. C1-7alkyl refers to an alkyl group having multiple carbon atoms selected from any one in an entire range (i.e., 1 to 7 carbon atoms) as well as all subgroups (e.g., 1-6, 2 -7, 1-5, 3-6, 1, 2, 3, 4, 5, 6, and 7 carbon atoms). Non-limiting examples of alkyl groups include, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl (2-methylpropyl), i-butyl (1,1-dimethylethyl), 3,3-dimethylpentyl, and 2 -ethylhexyl. Unless otherwise indicated, an alkyl group may be an unsubstituted alkyl group or a substituted alkyl group.

[024] The term “aryl”, alone or in combination, means an aromatic carbocyclic system that contains one or two rings in which such rings can be attached together in a fused manner. The term “aryl” encompasses aromatic radicals, including, without limitation, phenyl, naphthyl, indenyl, tetrahydronaphthyl, and indanyl. In certain embodiments, aryl is phenyl. Said “aryl” group may have 1 to 3 substituents such as lower alkyl, hydroxyl, halo, haloalkyl, nitro, cyano, alkoxy and lower alkylamino. Phenyl substituted with -O-CH2-O- forms the aryl benzodioxolyl substituent. Unless otherwise indicated, an aryl group may be an unsubstituted aryl group or a substituted aryl group.

[025] The term “heteroaryl” as used herein refers to monocyclic or polycyclic aromatic ring systems (e.g., fused bicyclic and fused tricyclic), in which one to four ring atoms are selected from oxygen, nitrogen, or sulfur. , and the remaining ring atoms are carbon, said ring system being joined to the remainder of the molecule by any of the ring atoms. Non-limiting examples of heteroaryl groups include, but are not limited to, pyridyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiadiazolyl, oxadiazolyl, furanyl, quinolinyl, isoquinolinyl, benzoxazolyl, benzimidazolyl, and benzothiazolyl . Unless otherwise indicated, a heteroaryl group may be an unsubstituted heteroaryl group or a substituted heteroaryl group.

[026] The term “alkoxy” encompasses linear or branched oxygen-containing radicals each having alkyl moieties of one to about ten carbon atoms. In certain embodiments, alkoxy radicals are “lower alkoxy” radicals that have one to six carbon atoms. Examples of such radicals include methoxy, ethoxy, propoxy, butoxy and tert-butoxy. In certain embodiments, they are lower alkoxy radicals that have one to three carbon atoms. Alkoxy radicals can also be substituted with one or more halo atoms, such as fluorine, chlorine or bromine, to provide “haloalkoxy” radicals. In certain embodiments, they are lower haloalkoxy radicals that have one to three carbon atoms. Examples of such radicals include fluormethoxy, chloromethoxy, trifluoromethoxy, trifluoroethoxy, fluorethoxy and fluorpropoxy.

[027] The term “alkyl ester” as used here refers to a group of general formula: where R is an alkyl group.

[028] The terms “enantiomeric excess” or “ee” refers to a measure of purity used for chiral substances, and reflects the degree to which one sample contains one enantiomer in greater quantities than the other. A racemic composition (i.e., a composition that has equal amounts of right- and left-hand enantiomers) has an ee of 0%, while a composition comprising pure enantiomer has an ee of 100%. A composition comprising 70% of one enantiomer and 30% of the other has an ee of 40%.

[029] The term “ee erosion” refers to a decrease in the ee of a solution or composition.

[030] The term “NAPA” refers to: (i) (R)-2- (3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanoic acid , (ii) a salt of (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanoic acid, or (iii) both (i) and (ii) together.

[031] The term “(S)-propionic acid/ester” refers to (i) a propionic acid with S stereochemistry, (ii) a propionic ester with S stereochemistry, or (iii) both (i) and (ii ) together.

[032] Additional modalities are disclosed herein. The disclosed embodiments illustrate various aspects that may be included in particular embodiments. It should be understood that the examples, although they indicate particular embodiments, are given as an illustration only. Compounds that can be obtained by the new methods described herein will be apparent to those of ordinary skill in the art, suitable procedures being described, for example, for providing a disclosed compound also describe how to obtain other triazolpyridines.

[033] Since the contribution of the present disclosure is not limited to particular modalities or aspects disclosed herein, the disclosure provides a person skilled in the art with additional modalities including changes and modifications to adapt to various uses and conditions. For example, changes and modifications to materials, synthetic methods, or procedures described herein will be apparent to a person of ordinary skill.

[034] As used in this specification and the attached claims, the singular forms “a”, “an”, “the” and “a” include plural referents, unless the content clearly defines otherwise. Thus, for example, reference to “a compound” is a reference to one or more compounds or molecules, and equivalents thereof known to those skilled in the art, and so on. The term “comprises” should be an open term, including the indicated element (e.g., component or step) but not excluding other elements.

[035] When ranges are used here for physical properties, such as molecular weight, or chemical properties such as chemical formulas, all combinations and subcombinations of ranges and specific modalities therein must be included.

[036] Although the disclosure and description of embodiments illustrate the contribution to the prior art, they are not intended to restrict or in any way limit the scope of the appended claims to such detail(s). Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broadest aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described.

[037] Therefore, deviations can be made from such details without departing from the spirit or scope of the general concept of the invention. Those skilled in the art will appreciate that numerous changes and modifications can be made to the disclosed embodiments and that such changes and modifications are within the scope of the present disclosure.

PREPARATION OF COMPOUND A

[038] In one aspect, provided herein is a method for preparing Compound A, salts of Compound A, and the monohydrate form of compound A. Compound A can be prepared from the starting materials NAPH, PIRH, and S-propionic acid/ester in three steps. First, NAPH and S-propionic acid/ester undergo an SN2 alkylation reaction to yield acid/ester (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H )-il)propanoic. S-propionic acid starting material produces (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanoic acid (“NAPA”) in one step. The S-propionic ester starting material first produces the ester analogue of NAPA, and is subsequently hydrolyzed to form NAPA. During evolution, the acid may optionally form a salt (e.g., HCl or 2-naphthalene sulfonic acid).Step 1: wherein R is Br, Cl, I or OTf; and R is COOH or C1-3 alkyl ester, and when R is C1-3 alkyl ester, the method of forming NAPA or salt thereof also comprises hydrolysis of the C1-3 alkyl ester to form an acid.

[039] Second, NAPA and PIRH are joined to form (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2- (3 -(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl)propanehydrazide (“HYDZ”).Step 2:

[040] Third, HYDZ is dehydrated to form Compound A. Step 3:

[041] The free base form of Compound A can be crystallized as a salt or a monohydrate. Step 1: Alkylation of NAPH to form NAPA

[042] The first step in the preparation of Compound A is the alkylation of NAPH to form NAPA. The NAPA product of the alkylation reaction is produced as a free base and is advantageously stable.

[043] Therefore, one aspect of the disclosure provides a method for preparing NAPA comprising the mixture of 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“NAPH”): and a basis, under conditions sufficient to form NAPA: wherein R1 is Br, Cl, I or OTf; and R2 is COOH or C1-3 alkyl ester; and when R2 is C1-3 alkyl ester, the method of forming NAPA or salt thereof also comprises hydrolysis of the C1-3 alkyl ester to form an acid.

[044] The compound represents a (S)-propionic acid and/or (S)-propionic ester (“(S)-propionic acid/ester”). When is an acid (i.e. R2 is COOH), NAPA is formed in one step:

[045] When is an ester (i.e., R2 is C1-3 alkyl ester), then the ester analogue of NAPA is formed, which can be hydrolyzed to form NAPA.

[046] The alkylation of SN2 of NAPH to form NAPA occurs with an inversion of stereochemistry of the (S)-propionic acid/ester starting material to form the R-enantiomer of NAPA. Therefore, the NAPA synthesis disclosed herein is advantageously stereoselective. Stereospecific alkylation of naphthyridinones such as NAPH, however, is challenging because naphthyridinones are sterically hindered, they have reduced nucleophilicity, the starting material and product are both sensitive to epimerization, and they have two nucleophiles (the nitrogen atoms and amide oxygen; therefore, O-alkylation or N-alkylation can potentially occur). Therefore, a method for stereo-specific alkylation of a NAPH in good yield and with high optical purity is disclosed herein.

[047] The degree of alkylation of a naphthyridinone, as well as the selectivity of N/O alkylation (N-alkylation versus O-alkylation), may depend on the base used in the reaction. The base used for the alkylation reaction disclosed herein may be a strong inorganic base, for example, a metal tert-butoxide with a Lewis acid cation. As specific examples, the base may be KOtBu, NaOtBu, LiOtBu, Mg(OtBu)2, Al(OtBu)3, NaOSiMe3, Cs2CO3, potassium bis(trimethylsilyl)amide (“KHMDS”), sodium bis(trimethylsilyl)amide (“ NaHMDS”), lithium bis(trimethylsilyl)amide (“LiHMDS”), or combinations thereof. In one aspect, the base may be selected from KOtBu, NaOtBu, NaOSiMe3, Cs2CO3, LiOtBu, Mg(OtBu)2, Al(OtBu)3, or combinations thereof; in another aspect the base may be Cs2CO3.

[048] The base may include magnesium. The use of a base that includes Mg advantageously results in greater reactivity and less ee erosion. Without being bound by any particular theory, magnesium is oxophilic and selectively binds to the amide oxygen atom in NAPA (rather than to the amide nitrogen atom). As a result, the nitrogen atom in NAPA amide is more reactive in the alkylation reaction, and the reaction is able to achieve high N-alkylation selectivity. Also without being bound by any particular theory, magnesium interacts with the carboxylate of the starting material. Therefore, an (S)-propionic acid starting material reacts more quickly than an (S)-propionic ester starting material.

[049] The base can be a combination of NaOtBu and Mg(OtBu)2 and/or KOtBu and Mg(OtBu)2. These combinations, particularly KOtBu and Mg(OtBu)2, result in excellent N/O selectivity and high optical purity for the SN2 alkylation reaction. Certain weak bases have been found to be inactive, including iPr2NEt. Certain metal oxide bases have been found to result in incomplete conversion, variable optical product purity, and poor N/O selectivity.

[050] In relation to the (S)-propionic acid/ester starting material, R1 can be Br, Cl, I or OTf.

[051] In one aspect, R1 can be Br or Cl. For example, the (S)-propionic acid/ester may include In another aspect, R1 is I or OTf.

[052] R2 of the (S)-propionic acid/ester starting material can be COOH. In these modalities, the (S)-propionic acid/ester can be For example, (S)-propionic acid can be The acid form of the (S)-propionic acid/ester starting material is advantageous because the formation of NAPA can be carried out in one step, and because the carboxyl group of the starting material can interact with a magnesium base.

[053] R2 of the (S)-propionic acid/ester can be C13 alkyl ester, such as OMe, OEt, OPr, or OiPr. In these embodiments, the (S)-propionic acid/ester can be For example, (S)-propionic acid can be When (S)-propionic ester is used as the starting material, the resulting ester is hydrolyzed to produce NAPA (the acid) in a second step. Hydrolysis can occur under acidic conditions, such as in the presence of HCl, AcOH, or a combination thereof. Alkyl acetate may form in situ during the hydrolysis process, but may be removed to achieve conversion (e.g., greater than about 90%).

[054] The alkylation reaction can occur in any suitable solvent. The solvent may be, for example, an ether solvent (e.g., tetrahydrofuran ("THF"), 2-methyltetrahydrofuran, tetrahydropyran), toluene, or acetonitrile.

[055] The reaction to form NAPA can occur at any suitable temperature. For example, the reaction may occur at a temperature in a range of 20°C to 80°C, or 25°C to 60°C, or 25°C to 45°C, or 25°C to 35°C. A lower temperature is more optimal for reducing ee erosion.

[056] Generally, the alkylation reaction may include alkylation of NAPH with (S)-2-bromopropionic acid or (S)-2-chloropropionic acid in THF, using NaOtBu/Mg(OtBu)2 or KOtBu/ Mg(OtBu)2 as base. In these embodiments, the alkylation reaction can occur in the ranges described above, or at a temperature of about 25 to 35°C. The ratio of magnesium base to sodium or potassium base may be in a range of about 1.5:1 to 2.5:1, for example, about 2:1. In one class of embodiments, the ratio of NAPH to (S)-2-chloropropionic acid is about 1:1 to about 1:2.5, or about 1:1.5.

[057] The free base NAPA product can contact a suitable acid or base to form a salt. For example, the free base may contact an acid selected from HCl, HBr, a sulfonic acid, a diisopropylamine, or a potassium cation. The sulfonic acid may be, for example, 2-naphthalene sulfonic acid (“NSA”), 1-naphthalene sulfonic acid, or m-xylene sulfonic acid, p-toluene sulfonic acid, benzene sulfonic acid, 2-nitrobenzene sulfonic acid, 2,5-dichlorobenzene sulfonic acid, (-)-10-camphorsulfonic acid, (+)-camphor-10-sulfonic acid, p-chlorobenzene sulfonic acid, methanesulfonic acid, or combinations thereof. For example, NAPA can contact aqueous 2-naphthalene sulfonic acid to form the salt.

[058] Propionic acid/ester starting materials are well known in the art, and are commercially available in high enantiomeric purity from numerous vendors (e.g., from SigmaAldrich). Triflate starting material can be prepared by reacting methyl lactate with Tf2O pyridine in dichloromethane. The byproduct of pyridinium triflate salt crystallizes from the reaction solution after addition of tert-butyl methyl ether, and can be removed by filtration. The resulting filtrate has a purity suitable for use in the alkylation reaction. The optical purity of the triflate product is high (e.g. greater than 98% ee) but may decrease over time.

[059] The resulting NAPA salt can be purified by any suitable purification method, for example, by crystallization, as described in further detail in the Examples section.

[060] In view of the teachings therein, NAPH alkylation can be in high yield (e.g., 95-97% crude and 80-90% isolated), and the NAPA product can have excellent purity (e.g., greater than 98 %). For example, alkylation of NAPH to form NAPA may have a yield of at least about 80%, at least about 90%, at least about 95%, or at least about 97%. The purity of the NAPA product may be at least about 95%, at least about 97%, at least about 99%, or at least about 99.5%. Furthermore, the reaction can result in a NAPA product that has high optical purity (e.g., 90-97% ee). The optical purity of NAPA may be at least about 90%, at least about 95%, at least about 97%, at least about 99%, or at least about 99.5% ee. Step 2: Bonding of NAPA and PIRH to form HYDZ

[061] The second step in the preparation of Compound A is the binding of NAPA with PIRH to form HYDZ.

[062] The linkage of NAPA and PIRH to form HYDZ occurs by reaction of the carboxyl group in NAPA with the amino group in PIRH via a linking agent to form an amide bond. Methods of linking a carboxyl group and an amino group to form an amide bond are well known to those skilled in the art. See, for example, Hermanson, Bioconjugate Techniques, 2nd ed, (2008).

[063] Therefore, in another aspect there is provided herein a method comprising the reaction of (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl acid )propanoic acid or a salt thereof (“NAPA”) with 3-fluoro-2-hydrazinyl-5-(1-methyl-1H-pyrazol-4-yl)pyridine (“PIRH”) and a binding reagent, and under conditions enough to form HYDZ.

[064] NAPA can be used in its free base form (i.e. zwitterionic) for the binding reaction.

[065] NAPA can be used in a salt form for the binding reaction. The salt form of NAPA may include HCl, HBr, a sulfonic acid, a diisopropylamine, or a potassium cation. The sulfonic acid may be, for example, 2-naphthalene sulfonic acid (“NSA”), 1-naphthalene sulfonic acid, or m-xylene sulfonic acid, p-toluene sulfonic acid, benzene sulfonic acid, 2-nitrobenzene sulfonic acid, 2-nitrobenzene sulfonic acid, ,5-dichlorobenzene sulfonic acid, (-)-10-camphorsulfonic acid, (+)-camphor-10-sulfonic acid, p-chlorobenzene sulfonic acid, methanesulfonic acid, or combinations thereof.

[066] Generally, the NAPA binding reaction may include HCl or a sulfonic acid (for example, NAPA/HCl or NAPA/2-naphthalene sulfonic acid). Sulfonic acids (e.g., 2-naphthalene sulfonic acid) unexpectedly resulted in an elevation of ee during the isolation of HYDZ.

[067] The binding reaction can proceed with the use of any suitable amide binding reagent. For example, the binding reagent may be a carbodiimide reagent, a phosphonium reagent, a uronium reagent, an imonium reagent, an imidazolium reagent, an organophosphorus reagent, an acid chloride reagent, a chloroformate reagent, or a pyridinium reagent. See, for example, Han & Kim, Tetrahedron Report 60:2447-2467 (2004); Montalbetti and Falque, Tetrahedron 61: 10,827- 10,852 (2005).

[068] The carbodiimide can be N,N'dicyclohexylcarbodimide (“DCC”), 1,3-diisopropylcarbodiimide (“DIC”), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (“EDC”), and isopropylcarbodimide ( “CIC”), for example.

[069] The phosphonium reagent can be (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (“BOP”) or benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (“PyBOP”), for example.

[070] The uronium reagent can be 1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazol[4,5-b] pyridinium 3-oxide hexafluorophosphate (“HATU”) or O-(Benzotriazole -1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (“HBTU”), for example.

[071] The imidazolium reagent can be 1,1'-carbonyldiimidazole ("CDI"), for example.

[072] The acid chloride reagent can be pivaloyl chloride or 2,4,6-trimethylbenzoyl chloride, for example.

[073] The chloroformate reagent can be ethyl chloroformate or isobutyl chloroformate, for example.

[074] In one aspect, the binding reagent can be selected from HATU and/or EDC. The use of EDC is advantageous because it does not have racemization or generate problems. For example, CDI can result in high levels of epimerization in the hydrazide product; ethyl chloroformate, iso-butylchloroformate, pivaloyl chloride, and 2,4,6-trimethylbenzoylchloride can each result in racemization and decreased yield. In another aspect, the binding reagent can be selected from HBTU, BOP and/or DCC.

[075] The binding reagent may be present in an amount in a range of about 1.0 equivalent to about 1.8 equivalent, or about 1.0 equivalent to about 1.5 equivalent (e.g., 1 ,1, or 1.2, or 1.3, or 1.4, or 1.5 equivalent). In one aspect, the binding reagent is present in an amount of about 1.2 equivalents. In another aspect, the binding reagent is present in an amount of about 1.3 equivalents.

[076] The binding reaction can be carried out in the presence of a binding additive. Binding Additives are known in the art and any that are suitable can be used for the formation of HYDZ. For example, the binding additive may be a benzotriazole.

[077] Examples of binding additives include benzotriazoles, dicarboximides, and succinimides. In one aspect the binding additives include one or more of N-hydroxysuccinimide ("HOSu"), N-hydroxy-5-norbornene-2,3-dicarboximide ("HONB"), 1-hydroxybenzotriazole ("HOBt"), 6 - chloro-1-hydroxybenzotriazole (“Cl-HOBt”), or 1-hydroxy-7-azabenzotriazole (“HOAt”). In another aspect the binding additive comprises HOBt; In yet another aspect, the binding additive comprises HOSu.

[078] The binding reaction can optionally occur in the presence of a base, for example, a tertiary amine base. Bases for binding reactions are well known in the art. In one aspect, the base is selected from N,N-diisopropylethylamine ("DIEA") triethylamine ("TEA"), N-methylmorpholino ("NMM"), and combinations thereof. In one class of embodiments, for example, when NAPA is used in its zwitterionic form, the base may be absent from the binding reaction. In other classes of embodiments, a base may be included in the binding reaction.

[079] The base may be present in an amount of at least about 1 equivalent, for example. Advantageously, when the base is present in an amount greater than 1 equivalent, racemization can be minimized to less than 1% ee. When the base is present in an amount less than 1 equivalent, a racemization greater than 2% ee has been observed.

[080] The binding reaction can occur in an aprotic solvent, for example, acetonitrile, dichloromethane, tetrahydrofuran, dimethylacetamide (“DMAc”), or a combination thereof. In one aspect the aprotic solvent comprises DMAc. DMAc is also advantageously a good solvent for recrystallization and isolation of the HYDZ product. In another aspect, the aprotic solvent comprises acetonitrile.

[081] The binding reaction can occur at any temperature that allows the reaction to proceed with good conversion. For example, the binding reaction may occur at a temperature in a range of 10°C to 30°C, or 15°C to 25°C, or 20°C. The binding reaction can also occur at a temperature in a range of about 0°C to 10°C, or 2°C to 8°C, or 5°C.

[082] In one type of embodiment, the binding reaction can be carried out using EDC as the binding reagent, HOBt as the binding additive, DIEA as the base, and DMAc as the solvent. The order of addition of reagents can affect product yield, purity, and optical purity. Thus, the order of addition can be: (1) NAPA/2-naphthalene sulfonic acid, DMAc, HOBt; (2) DIEA, (3) PIRH, (4) EDC. In experiments, when NAPA was added last, it was found that the result was little conversion due to the reaction of EDC and PIRH. In experiments, when PIRH was added last, significant racemization was observed. In experiments, when DIEA was added after PIRH, a thick reaction mixture resulted. No binding reaction occurred in the absence of EDC.

[083] Therefore, EDC can be added last to start the reaction. In these embodiments, the NAPA/2-naphthalene sulfonic acid, HOBt, and DMAc may be present in an amount of about 1.0 equivalent, about 1.0 equivalent, and about 4.6 volumes, respectively, for example. DIEA may be present in an amount of about 1.0 equivalent to about 1.2 equivalent (e.g. 1.05 equivalent), for example. PIRH may be present in an amount of about 1.1 equivalent, for example. The EDC may be present in an amount of about 1.0, or 1.1, or 1.2, or 1.3, or 1.4, or 1.5 equivalent, for example, (e.g., 1. 2 or 1.3 equivalent). EDC can be added slowly to the reaction mixture (e.g., 4 portions per 1 hour).

[084] HYDZ can advantageously crystallize directly from the reaction solution after adding water in high optical purity.

[085] Furthermore, the HYDZ product can be purified by any suitable method known in the art. For example, the HYDZ product can be crystallized in water and DMAc, as also described in the Examples section.

[086] In view of the teachings herein, the ligation reaction can be done to result in a stable HYDZ product in good yield (for example, greater than 95% crude, and about 78%-84% isolated). For example, the formation of HYDZ from NAPA and PIRH can result in a yield of at least about 75%, at least about 85%, at least about 90%, or at least about 95%. The loss from gross yield to isolated yield is due to a built-in crystallization that allows an increase in ee from greater than 99% to about 100%. Therefore, the optical purity of HYDZ may advantageously be at least about 99%, at least about 99.5%, at least about 99.7%, at least about 99.9%, or about 100% of and is. The purity of HYDZ resulting from binding of NAPA and PIRH can be excellent (e.g., at least about 95%, at least about 97%, at least about 99%, at least about 99.5%, or about 100%).Step 3: Dehydration of HYDZ to form Compound A

[087] The third step in the preparation of Compound A is the dehydration of HYDZ to form Compound A:

[088] In particular, the third step in the preparation of Compound A is the dehydration of hydrazine in HYDZ to form Compound A, a compound that has a triazolpyridine bicycle nucleus. Compound A can be isolated as a salt form (e.g., HCl salt) or in a monohydrate form, and is stable in air, humidity, and elevated temperature.

[089] Therefore, in another aspect a method is provided herein that includes the reaction of (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl )-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl)propanehydrazide (“HYDZ”) under conditions sufficient to form (R)-6-(1-( 8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy )-1,6-naphthyridin-5(6H)-one (“A”).

[090] Numerous reagents can be used for the dehydration reaction. However, HYDZ has a chiral center adjacent to the carbonyl carbon, which is particularly susceptible to epimerization. Therefore, retention of the chiral center of HYDZ during dehydration can be challenging. Disclosed herein are methods for carrying out the dehydration of HYDZ to form Compound A, whilst retaining the chiral center of HYDZ. Route 1: Thiophosphetan-mediated dehydration

[091] HYDZ can be dehydrated by contacting it with a thiophosphethane compound. The thiophosphetan compound may be a 2,4-bis(aryl)-1,3-dithia-2,4-diphosphetan 2,4-disulfide compound, for example. Upon heating, the thiophosphetan compound can undergo a ring opening reaction to form two reactive dithiophosphine ylides, as shown by the partial structures below. See, Lawson et al., Tet. Lett 41:4,533-4,536 (2000) and Fehrentz et al., Tet Lett 47:7,591-7,594 (2006)).

[092] The compound 2,4-bis(aryl)-1,3-dithia-2,4-diphosphetan 2,4-disulfide can be Lawesson's reagent or Belleau's reagent:

[093] In one aspect, Lawesson's reagent can be used; in another aspect, Belleau's reagent can be used.

[094] The formation of Compound A by contact of HYDZ with a thiophosphethane compound can have several advantages. Dehydration can occur quickly, with selectivity for the desired product. The selectivity is due to the reactive, oxophilic 3-coordinated reagent P(III) that forms in solution. The pH of the reaction solution is low; therefore, dehydration occurs with minimal erosion of optical purity. Furthermore, dehydration by-products can be easily removed, and dehydration can advantageously result in a high yield.

[095] Various reaction conditions can affect the conversion of the dehydration reaction and the optical purity of Compound A, for example, the reaction temperature, the order of addition of the reagents, the addition method, and the equivalents of the thiophosphetan compound.

[096] For example, the temperature of the dehydration reaction may be in a range of 35°C to 70°C, or 40°C to 60°C, or 45°C to 55°C. When the dehydration reaction temperature is 45°C to 55°C (e.g., 50°C), there is no sticky broth, and the result is good optical purity. Therefore, the dehydration reaction can age at about 45°C to 55°C until the reactive intermediates are consumed, which typically occurs over several hours (e.g., at least 2 hours, at least 3 hours, or at least least 4 hours). When reactive intermediates are not sufficiently consumed, they can persist into the isolation step and trigger the decomposition of Compound A (e.g., HCl decomposition) via removal of the methoxyethyl side chain.

[097] The dehydration reaction can be carried out by making a broth of the thiophosphetan compound (for example, in acetonitrile), and adding HYDZ to the broth. When HYDZ is added to a broth of the compound thiophosphetan, there is little or no loss of optical purity of the resulting Compound A. Alternatively the thiophosphetan compound can be added to a HYDZ broth. In one example of this type of modality, however, the optical purity of Compound A was lower.

[098] HYDZ can be added to the thiophosphetan broth in portions or as a broth itself.

[099] The thiophosphetan compound may be present in the dehydration reaction in an amount of at least about 0.4 equivalent, or at least about 0.45 equivalent, or at least about 0.5 equivalent, for example, or an amount in a range of about 0.4 equivalent to about 0.65 equivalent, or about 0.45 equivalent to about 0.65 equivalent, or about 0.5 equivalent to about 0.55 equivalent. For example, thiophosphetan may be present in an amount of at least about 0.5 equivalent, or a range of about 0.5 equivalent to about 0.55 equivalent.

[100] For example, the dehydration reaction can be carried out by making a broth of about 0.5 to about 0.6 equivalents of the thiophosphetan compound (e.g., 0.52 equivalents) in acetonitrile at about 20°C. , adding HYDZ in portions to the broth for one or two hours, and heating the resulting composition to about 50°C until about 99% consumption of the HYDZ occurs. Therefore, in one aspect, the dehydration reaction is carried out by making a broth of the compound thiophosphetan and adding HYDZ thereto.

[101] In another aspect, the dehydration reaction can be carried out by mixing the thiophosphetan compound, HYDZ, and solvent together, and then heating the resulting composition, without using a broth.

[102] The crystalline free base monohydrate form of Compound A can be isolated directly from the dehydration reaction solution. A water-rich crystallization solvent of pH 7 or greater (e.g., an acetonitrile/water solution that is about 80% to about 90% water) can quench any residual thiophosphethane compounds, facilitating removal of acid byproducts. thiophosphonic acid as a salt, and facilitate removal of the smaller enantiomer.

[103] For example, the free base monohydrate form of Compound A can be isolated by concentrating the reaction solution (e.g., to about three volumes or less), and then adding to the reaction solution of K2CO3 (e.g. , about 1.1 equivalent of a 10% solution by weight) together with water (e.g., about four volumes). The resulting solution can be seeded with the monohydrate form of compound A (e.g., about 1 mol%), aged (e.g., for about 1 hour), introduced to more water (e.g., about four volumes) , and aged (e.g., to a supernatant concentration of less than about 8 mg/ml if obtained). Crystals resulting from the freebase monohydrate form of Compound A advantageously meet purity requirements for preclinical and clinical use (e.g., greater than about 99.5% purity and greater than about 99.9% purity). and is). For example, the purity may be at least about 99.5%, or at least about 99.7%, or at least about 99.9%, or about 100%; and the optical purity can be at least about 99.9% or about 100%. Therefore, they do not need to be recrystallized. However, crystals can be recrystallized to also increase purity. The formation of the monohydrate form of compound A is also described in the Examples section.

[104] In other embodiments, Compound A can be isolated as a salt, for example, a pharmaceutically acceptable salt. Therefore, provided herein is a method for preparing a salt of Compound A which comprises contacting Compound A with an acid under conditions sufficient to form the salt of Compound A. The acid may be any suitable acid. For example, the acid may be selected from the group consisting of hydrochloric acid, phosphoric acid, camphorsulfonic acid, 2-naphthylsulfonic acid, methanesulfonic acid, benzenesulfonic acid and derivatives thereof, succinic acid, tartaric acid, fumaric acid, and maleic acid. The salt of Compound A can be prepared by subjecting the reaction solution to evolution, and adding concentrated acid to the resulting solution, optionally adding a salt of compound A to the solution, and adding antisolvent to the solution.

[105] The HCl salt of Compound A, for example, can be prepared by subjecting the reaction solution to evolution (e.g., K2CO3, as described above), and then adding concentrated HCl to the quenched solution. The resulting solution can be optionally added with the HCl salt of Compound A, and antisolvent can be added to the solution to initiate crystallization. In particular, the solution may be aged at elevated temperature (e.g., 70°C) for a period of time (e.g., at least about 15 minutes) to ensure that the addition takes effect, and then cooled (e.g., at about 20°C) for a period of about one hour, before the antisolvent (e.g., heptane) is added to the cooled solution for aging at the cooled temperature. The resulting crystals of the HCl salt of compound A can be isolated and dried. The formation of the HCl salt of Compound A is also described in the Examples section.

[106] The HYDZ dehydration reaction using a thiophosphethane compound can result in a high yield of Compound A or a salt thereof (e.g., greater than 99% crude, and about 88% isolated). For example, the yield may be at least about 80%, at least about 90%, at least about 95%, or at least about 99%. Furthermore, the purity of Compound A or a salt may be at least about 99%, at least about 99.5%, or at least about 99.7%. Although HYDZ has a chiral center adjacent to its reactive carbonyl carbon, dehydration of HYDZ using a thiophosphethane compound produces Compound A, or a salt thereof, in high optical purity. For example, the optical purity of Compound A, or a salt thereof, may be at least about 98%, at least about 99%, at least about 99.5%, or at least about 99.9% ee .

[107] Dehydration of thiophosphetan from HYDZ to form Compound A, a salt thereof, or the monohydrate form is also described in the Examples section. Route 2: Phosphorus (V)-mediated dehydration

[108] HYDZ can be dehydrated by contact with a phosphorus (V) dehydrating agent.

[109] The dehydrating agent can be, for example, a phosphinyl halide compound or a phosphoryl halide. The dehydrating agent may have a structure: wherein each L is independently C1-6 alkyl, O-C1-6 alkyl, aryl, O-aryl, Cl, Br, or I; and R1 is Cl, Br, or I.

[110] For example, each L of the dehydrating agent can independently be a C1-4 alkyl group (e.g., Me, Et, Pr, iPr, n-Bu, s-Bu, i-Bu, or t-Bu) , or an O-C1-4 alkyl group (e.g., OMe, OEt, OPr, OiPr, O-n-Bu, O-s-Bu, O-i-Bu, or O-i-Bu). Each L may also be an aryl group, e.g. phenyl, or an O-aryl group, e.g. O-phenyl. Each L can also be a halogen (e.g., Br, Cl, or I). In embodiments, one L may be a C1-4 alkyl group, and the other L may be an aryl group. In other embodiments, each L is phenyl. R1 can be Cl, Br, or I. In one aspect, R1 is Cl. In another aspect, R1 is Br. For example, the dehydrating agent may be diphenylphosphinyl chloride (Ph2P(O)Cl); in another example the dehydrating agent may be POCl3.

[111] The dehydrating agent may be present in an amount of about 1.5 equivalents to about 3.5 equivalents, or about 2.0 equivalents to about 3.0 equivalents {for example, 2.5 equivalents ).

[112] The base can be any base capable of carrying out the desired dehydration reaction. Pyridine bases can be used. For example, the base may be selected from 2,4-lutidine, 2,4,6-collidine, or a combination thereof. The base may be present in the reaction mixture in excess. For example, the base may be present in an amount that is at least about 0.2 equivalent greater than the amount of the dehydrating agent. The base may be present in an amount of about 2.5 to about 4.0 equivalents, or about 2.5 to about 3.5 equivalents, for example.

[113] The solvent can be any solvent in which the dehydration reaction can occur with good conversion and optical purity. For example, the solvent may be an amide, sulfolane solvent, or nitrile. The solvent may be, for example, N-methyl-2-pyrrolidone ("NMP"), dimethylacetamide ("DMAc"), acetonitrile, propionitrile, and combinations thereof.

[114] The dehydration reaction can occur at an elevated temperature, such as greater than about 60°C, greater than about 70°C, or greater than about 80°C, up to about 90°C. the reaction may occur at the reflux temperature of the reaction solution, for example about 83°C to about 86°C in some embodiments.

[115] After the end of the reaction, it can be quenched (for example, with K2CO3/KCl), as also described in the Examples section.

[116] Compound A can be isolated from the quenched solution as a salt, as described in the previous section. The salt may be the salt of hydrochloric acid, phosphoric acid, camphorsulfonic acid, 2-naphthylsulfonic acid, methanesulfonic acid, benzenesulfonic acid and derivatives thereof, succinic acid, tartaric acid, fumaric acid, or maleic acid, and combinations thereof, for example. In one aspect, the salt is the hydrochloric acid salt. Generally, concentrated HCl can be added to the quenched solution containing Compound A, the resulting solution can be seeded with the HCl salt of Compound A, and antisolvent can be added to the solution to initiate crystallization. In particular, the seeded solution may be aged at elevated temperature (e.g., 70°C) for a period of time (e.g., at least about 15 minutes) to ensure that seeding occurs, and then cooled (e.g., at about 20°C) for a period of about one hour, before the antisolvent (e.g., heptane) is added to the cooled solution for aging at the cooled temperature. The resulting crystals of the HCl salt of compound A can be isolated and dried. The formation of the HCl salt of Compound A is also described in the Examples section.

[117] In view of the teachings thereof, the HYDZ dehydration reaction that uses a phosphorus (V) dehydrating agent to form Compound A can occur in good yield, as well as subsequent isolation of a salt of compound A, as here described. For example, the yield of the Compound A salt may be at least about 85%, at least about 90%, at least about 95%, or at least about 99%. Furthermore, the purity of the Compound A salt may be at least about 88%, at least about 90%, or at least about 95%. The use of a phosphinyl halide compound can produce a salt of compound A in high optical purity (e.g., greater than 99.5% ee). For example, the optical purity of a salt of compound A may be at least about 99%, at least about 99.5%, at least about 99.8%, or at least about 99.9% ee.

[118] Dehydration of phosphinyl halide of HYDZ to form a salt (e.g., HCl salt) of Compound A is also described in the Examples section. Route 3: Mitsunobu-Mediated Dehydration

[119] HYDZ can be dehydrated by subjecting it to Mitsunobu conditions. For example, HYDZ can be dehydrated by contact with a phosphine, wherein each L' is independently an alkyl, aryl, or heteroaryl group; and an oxidant.

[120] For example, each L' of the phosphine can independently be a C1-6 alkyl group, or a C1-4 alkyl group (e.g., Me, Et, Pr, iPr, n-Bu, s-Bu, i- Bu, or t-Bu). Each L' can also independently be an aryl group, e.g. phenyl, or a heteroaryl group (e.g. pyridine). In embodiments, one L' may be a C1-4 alkyl group, and the other L' may be an aryl group. In other embodiments, each L' is phenyl. In other embodiments, each L' may be an aryl group or a heteroaryl group. For example, the phosphine may be triphenyl phosphine, trimethyl phosphine, or diphenyl-2-pyridylphosphine. In one aspect the phosphine is triphenyl phosphine. In another aspect, phosphine is trimethyl phosphine. In another aspect, the phosphine is diphenyl-2-pyridylphosphine.

[121] Phosphine may be present in any amount suitable to effect the dehydration reaction. For example, phosphine may be present in a range of about 1 equivalent to about 2 equivalents, e.g., about 1.1 equivalents, or about 1.2 equivalents, or about 1.3 equivalents, or about of 1.4 equivalent, or about 1.5 equivalent, or about 1.6 equivalent, or about 1.7 equivalent, or about 1.8 equivalent, or about 1.9 equivalent. In one aspect, the phosphine is present in a range of about 1.0 equivalent to about 1.5 equivalent (e.g., about 1.2 equivalent to about 1.4 equivalent). In another aspect, phosphine is present in a range of about 1.5 equivalents to 2.0 equivalents (e.g., about 1.6 equivalents to about 1.8 equivalents).

[122] The oxidant can be any agent capable of serving as a repository for two hydrogen atoms. Examples of the oxidant may include a benzoquinone (e.g., 2,3-dichloro-5,6-dicyanobenzoquinone (“DDQ”)), azodicarboxylates, aryl and/or heteroaryl disulfides, aryl and heteroaryl hypochlorothioites, and combinations thereof. In one aspect the oxidizer is DDQ. In another aspect, the oxidant is an azodicarboxylate (e.g., diethyl azodicarboxylate ("DEAD"), diisopropyl azodicarboxylate ("DIAD"), di-(4-chlorobenzyl)azodicarboxylate). In another aspect, the oxidant is an aryl or heteroaryl hypochlorothioite. In another aspect, the oxidant is an aryl or heteroaryl disulfide. For example, the oxidant may be benzothiazyl disulfide.

[123] The oxidant may be present in any quantity suitable to effect the dehydration reaction. For example, the oxidant may be present in a range of about 1 equivalent to about 2 equivalents, e.g., about 1.1 equivalents, or about 1.2 equivalents, or about 1.3 equivalents, or about of 1.4 equivalent, or about 1.5 equivalent, or about 1.6 equivalent, or about 1.7 equivalent, or about 1.8 equivalent, or about 1.9 equivalent. In one aspect, the oxidant is present in a range of about 1.0 equivalent to about 1.5 equivalent (e.g., about 1.2 equivalent to about 1.4 equivalent). In another aspect, the oxidant is present in a range of about 1.5 equivalents to 2.0 equivalents (e.g., about 1.6 equivalents to about 1.8 equivalents). In another aspect, the oxidant is present in a range of about 1.4 to about 1.7 equivalent.

[124] Dehydration may also include an azide. Azide may be present in any amount suitable to effect the dehydration reaction. For example, the azide may be present in a range of about 1 equivalent to about 2 equivalents, for example, about 1.4 to about 1.7 equivalents. In one aspect, the azide is trimethylsilyl azide (“TMS azide”). In one aspect, the dehydration reaction includes an azide. In another aspect, the dehydration reaction does not include an azide.

[125] The solvent can be any suitable solvent, and can be selected to provide good conversion and optical purity in the dehydration reaction. For example, the solvent may be a chlorinated solvent, an ether solvent (e.g., tetrahydrofuran, diethyl ether), and/or acetonitrile.

[126] The dehydration reaction can occur at a temperature below 40°C, for example. For example, the dehydration reaction may occur at a temperature in a range of 15°C to 35°C, or 20°C to 30°C, e.g. 25°C. In another aspect, the dehydration reaction can occur at a temperature in a range of 30°C to 70°C. For example, the dehydration reaction can occur at a temperature in a range of about 40°C to about 60°C. In one aspect, the temperature is about 50°C.

[127] After the end of the reaction, the reaction can be subjected to reaction evolution and purified, for example, by flash chromatography or medium pressure liquid chromatography, to result in Compound A.

[128] In view of the teachings thereof, the HYDZ dehydration reaction using Mitsunobu conditions can result in excellent conversion (e.g., greater than 99%) and selectivity of the desired Compound A over the benzothiazol-2-thiol adduct ( “BtSH”) (e.g., about 94:6, or about 95:5, or about 96:4).

[129] In view of the teachings thereof, the HYDZ dehydration reaction that uses Mitsunobu conditions to form Compound A can occur in good yield. For example, the yield of Compound A may be at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, at least about at least about 85%, at least about 90%, at least about 95%, or at least about 99%. Furthermore, the purity of Compound A may be at least about 97%, at least about 99%, or about 100%. Using Mitsunobu conditions to dehydrate HYDZ to form Compound A can occur at high optical purity (e.g., greater than 95%, or greater than 97%, greater than 99%, or greater than 99.5%, or greater to 99.6%, or greater than 99.9% of ee).

[130] Compound A that results from dehydration of HYDZ using Mitsunobu conditions can be converted to a salt. For example, compound A can be converted to hydrochloric acid, phosphoric acid, camphorsulfonic acid, 2-naphthylsulfonic acid, methanesulfonic acid, benzenesulfonic acid and derivatives thereof, succinic acid, tartaric acid, fumaric acid, or maleic acid, or combinations thereof. . In one aspect, compound A resulting from dehydration of HYDZ using Mitsunobu conditions can be converted to its HCl salt by contacting it with a concentrated HCl solution at elevated temperature, seeded with Compound A-HCl, and crystallized .

[131] Mitsunobu dehydration of HYDZ to form compound A is also described in the Examples section. Route 4: Acetic acid-mediated dehydration

[132] HYDZ can be dehydrated to Compound A by contacting it with acetic acid at an elevated temperature, for example, at least 100°C, or at least 110°C, or at least 120°C, or at least 130° C, or greater. For example, HYDZ can be dehydrated to Compound A by contacting it with acetic acid for three days at 110°C or greater, e.g., 120°C. The dehydration reaction results in racemic material. Other acids, such as trifluoroacetic acid, acetic acid, methanesulfonic acid, polyphosphoric acid, and toluenesulfonic acid, can be used for the dehydration reaction. However, these acids did not result in as good a conversion of HYDZ to Compound A as with acetic acid in experiments. The contact of HYDZ with acetic acid produced two impurities in experiments. The optical purity of Compound A as a result of acetic acid-mediated dehydration can be about 80% ee, which is about a 15% decrease in optical purity of the starting material. The decrease in optical purity likely results from harsh and acidic cyclization conditions.

Formation of compound A monohydrate

[133] The monohydrate form of compound A is advantageously stable and robust in a range of about 15% to about 95% relative humidity, and up to about 50°C. Furthermore, the formation of the monohydrate form of compound A can provide particle size control.

[134] As described above, the monohydrate form of compound A can be formed directly from the solution of the final stage reaction of the dehydration of HYDZ to Compound A.

[135] The monohydrate form of compound A can also be formed from the HCl salt of Compound A. In this embodiment, the HCl salt of Compound A can be broken down and crystallized to form the monohydrate form of compound A.

[136] The HCl salt of compound A can be broken down and crystallized in a solvent that includes alcohol and water. The alcohol may be, for example, methanol, ethanol, and isopropanol. In one aspect the alcohol may include isopropanol. In another aspect, the alcohol may include ethanol. In another aspect, the alcohol may include methanol. The ratio of alcohol to water may be in a range of about 1:10 or about 10:10, for example, including about 1:1, or about 1:2, or about 1:3, or about of 1:4, or about 1:5, or about 1:6, or about 1:9, or about 1:8, or about 1:9, or about 1:10, or about 10:1, or about 9:1, or about 8:1, or about 7:1, or about 6:1, or about 5:1, or about 4:1, or about 3 :1, or about 2:1. For example, the ratio of alcohol to water may be about 1:3, or about 1:4, or about 1:5, or about 1:6, or about 2:1.

[137] For example, the breakdown of the HCl salt can occur by dissolving the HCl salt in an alcohol/water solution {e.g., 2:1 isopropanol/water), adding a sodium bicarbonate solution to the salt solution of HCl at a temperature below 30°C, then increasing the temperature to about 60°C and filtering the reaction solution. In another aspect, salt breakdown can occur at a temperature in a range of about 50°C.

[138] Crystallization to form the monohydrate of Compound A can proceed by dissolving Compound A in water, increasing the temperature of the solution to about 60°C, and introducing a seed crystal of Compound A by combining it with a solution of alcohol/water (e.g. 20:80 isopropanol/water, or 20% IP A/water, or 30% ethanol/water). The resulting solution, which is optionally rinsed with the alcohol/water solution, may be aged at 55-60°C for at least about 15 minutes, and then cooled (e.g., to about 20°C). The monohydrate form of compound A can be isolated by filtration and washed.

[139] The crystallization procedure can provide crystals of the monohydrate form of compound A in good yield (e.g., at least about 95%, at least about 97%, at least about 99% yield), and excellent purity (e.g., at least about 99%, at least about 99.5%, at least about 99.7%, or at least about 99.9%). Furthermore, the monohydrate crystals can exhibit excellent optical purity (e.g., at least about 99.5%, at least about 99.7%, or about 100%).

[140] The conversion of the HCl salt of Compound A to the monohydrate form is also described in the Examples section.

PIRH PREPARATION

[141] As described above, 3-fluoro-2-hydrazinyl-5-(1-methyl-7H-pyrazol-4-yl)pyridine (“PIRH”) is one of the three starting materials used to prepare Compound A. Another aspect of the disclosure provides a method for preparing PIRH by: (i) mixing and a catalyst, under conditions sufficient to form an intermediate: wherein (a) Y is F, Cl, Br, I or OTf, and Z comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin, or silicon; or (b) Y comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin, or silicon, and Z is F, Cl, Br, I or OTf; and (ii) mixing of and H2NNH2, under conditions sufficient to form PIRH:

[142] More specifically, PIRH can be prepared in two steps: (1) a metal-catalyzed cross-linking reaction of a 1-methyl-1H-pyrazolyl compound and a difluoropyridine compound to form a 2,3-difluoro- 5-(1-methyl-1H-pyrazol-4-yl)pyridine, and (2) reaction of the intermediate with hydrazine to form PIRH: wherein: (a) Y is F, Cl, Br, I or OTf, and Z comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin, or silicon; or (b) Y comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin, or silicon, and Z is F, Cl, Br, I or OTf.

[143] The PIRH preparation disclosed here results in a crystalline product that is stable when stored at room temperature and protected from light and air. Although samples that are exposed to air for a month develop some degree of coloring, they do not show any change in purity or weight by HPLC.Step 1: Preparation of Intermediate

[144] The first step in the preparation of PIRH is a metal-catalyzed cross-linking reaction of a 1-methyl-1H-pyrazolyl compound and a 2,3-difluoropyridine compound to form the intermediate, 2,3-difluoro-5- (1-methyl-1H-pyrazol-4-yl)pyridine. In particular, the first step is the cross-linking of an organometallic compound with a halide or a triflate. Such cross-linking of organometallic compounds and halides or triflates is well known in the art (see, for example, U.S. Patent No. 6,686,428, Clayden, Organic Chemistry pp. 1324-1332, Oxford University Press (2010)).

[145] In one class of embodiments, the 1-methyl-1H-pyrazolyl compound is the halide or triflate, and the 2,3-difluoropyridine compound is the organometallic compound. In these embodiments, Y is F, Cl, Br, I, or OTf, and Z comprises boron (e.g., boronic acid, boronic ester, or boronate), magnesium, zinc, zirconium, tin, or silicon.

[146] In another class of embodiments, the 1-methyl-1H-pyrazolyl compound is the organometallic compound, and the 146.3-fluoropyridine compound is halide or triflate. In these embodiments, Y comprises boron (e.g., boronic acid, boronic ester, or boronate), magnesium, zinc, zirconium, tin, or silicon, and Z is F, Cl, Br, I, or OTf.

[147] The organometallic compound may comprise boron, and may be a boronic acid or boronic ester, or a boronate. When the organometallic compound is a boronic acid, boronic ester, or boronate, the reaction is a Suzuki-type cross-linking reaction.

[148] In one aspect boronic acid can be used as an organometallic compound. In another aspect, boronic ester can be used as an organometallic compound. Examples of boronic esters include pinacolborane and catecholborane. In still other aspects, boronates may be used, for example, 9-borabicyclo[3.3.1]nonane ("9-BBN"), an N-methyliminodiacetic acid boronate ("MIDA boronate") and 2-hydroxy-4, 4,5,5-tetramethyl-2-(1-methyl-1H-pyrazol-4-yl)-1,3,2-dioxaborolan-2-ide:

[149] In one aspect, boronate, is used and can be prepared according to the process reported in Stewart et al., Org. Process Res. Dev. 14:849858 (2010). Boronic acids, boronic esters, and boronates are described in Leenox et al. Chem Soc Rev 43:412 (2014).

[150] The organometallic compound may include magnesium. When the organometallic compound includes magnesium, the reaction is a Kumada-type cross-linking reaction.

[151] The organometallic compound may include zinc. When the organometallic compound includes zinc, the reaction is a Negishi-type cross-linking reaction.

[152] The organometallic compound may include tin. When the organometallic compound includes tin, the reaction is a Stille-type cross-linking reaction.

[153] The organometallic compound may include silicon. When the organometallic compound includes silicon, the reaction is a Hiyama-type reaction.

[154] Suzuki, Kumada, Nehishi, Stille, and Hiyama cross-linking reactions are well known in the art. See, for example, Nicolaou et al., “Palladium Catalyzed Transformations in Organic Synthesis” “Angewandte Chemie International Edition”, 44(29):4,442-4,489 (2005).

[155] The cross-linking reactions described here can achieve good stereospecificity and yield in the presence of a transition metal catalyst. Useful transition metal catalysts for the cross-linking reactions disclosed herein include palladium (0), palladium (II), nickel, copper, and iron. For example, in one aspect palladium (0) and palladium (II) catalysts can be used. Suitable catalysts may include Pd2(dba)3, Pd(PPh), PEPPSTSIPr, or a paladacycle selected from the group consisting of a DavePhos, an XPhos, a SPhos, a JohnPhos, a RuPhos, a BrettPhos, a JackiePhos, a CPhos , and combinations thereof.

[156] Specific examples of suitable catalysts include: 2-Dicyclohexylphosphino-2'-(N,N-dimethylamino)biphenyl (“DavePhos”), 2-Dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (“XPhos”) , 2-Dicyclohexylphosphine-2',6'-dimethoxybiphenyl (“SPhos”), 2-Di-tert-butylphosphine-2',4',6'-triisopropylbiphenyl (“tBuXPhos”), (2-Biphenyl)dicyclohexylphosphine (“ CyJohnPhos”). , 2-Di-tert-butylphosphine-3,4,5,6-tetramethyl-2',4',6'-triisopropyl-1,1'-biphenyl (“tetramethyl tBuXPhos”), 2-Dicyclohexylphosphine-2', 6'-diisopropoxybiphenyl (“RuPhos”), 2'-(Diphenylphosphine)-N,N'-dimethyl-(1,1'-biphenyl)-2-amine, 2-diphenylphosphine-2'-(N,N-dimethylamino )biphenyl (“PhDave-Phos”), 2'-(Di-tert-butylphosphino)-N,N-dimethylbiphenyl- 2-amine (“t-BuDavePhos”), 2-Dicyclohexylphosphino-2'-methylbiphenyl, 2-Methyl -2'-dicyclohexylphosphinobiphenyl (“MePhos”), 2-Di-tert-butylphosphino-2'-methylbiphenyl(“tBuMePhos”), (2-Biphenyl)di-tert-butylphosphine gold (I) chloride “JohnPhos”), 2 -Dicyclohexylphosphino- 2',4',6'-triisopropylbiphenyl gold(I) chloride (“XPhos AuCl”), 2-Dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl gold(I) bis(trifluoromethanesulfonyl)imide (“ XPhos AuNTf2”), 2-(Dicyclohexylphosphino)3,6-dimethoxy-2',4',6'-triisopropyl- 1,1'-biphenyl (“BrettPhos”), Chloro(2-dicyclohexylphosphine- 2',4' ,6'-triisopropyl-1,1'-biphenyl)[2-(2-aminoethyl)phenyl)] palladium(II) (“XPhos Paladaciclo”), Chloro(2-dicyclohexylphosphine-2',6'-dimethoxy-1 ,1'-biphenyl) [2-(2-aminoethylphenyl)]palladium(II)-methyl-i-butyl ether adduct (“SPhos Paladaciclo”), t-BuXPhos palladium(II) phenethylamine chloride (“tBuXPhos Pd G1”) , 2-{Bis[3,5-bis(trifluoromethyl)phenyl]phosphine}-3,6-dimethoxy-2',4',6'-triisopropyl-1,1'-biphenyl (“JackiePhos”), 2- (Di-tert-butylphosphine)-2',4',6'-triisopropyl-3,6-dimethoxy-1,1'- biphenyl (“tBuBrettPhos”), Dicyclohexyl(2',4',6'- trimethoxy[ 1,1'-biphenyl]-2-yl)-phosphine (“BrettPhos Pd G1 Methyl-1-Butyl ether adduct”), Chloro(2-dicyclohexylphosphino- 2',4',6'-triisopropyl-1,1 '-biphenyl) [2-(2'-amino-1,1'- biphenyl)]palladium(II) (“Xphos Pd G2”), Chloro(2-dicyclohexylphosphine-2',6'-dimethoxy-1,1 '-biphenyl) [2-(2'-amino-1,1'-biphenyl)]palladium(II) (“SPhos Pd G2”), Chloro(2-dicyclohexylphosphine-2',6'-diisopropoxy-1,1 '-biphenyl)[2-(2'-amino-1,1'-biphenyl)]palladium(II) (“RuPhos Pd G2”), Chloro[(2-dicyclohexylphosphino-2',6'-bis(N, N-dimethylamino)-1,1'-biphenyl)-2-(2'-amino-1,1'-biphenyl)]palladium(II) (“CPhos-Pd- G2”), [(2-Dicyclohexylphosphine-2 ',6'-bis(N,N-dimethylamino)- 1,1'-biphenyl)-2-(2'-amino-1,1'-biphenyl)]palladium(II) methanesulfonate (“CPhos-Pd-G3 ”), [(2-Di-tert-butylphosphine- 2',4',6'-triisopropyl-1,1'-biphenyl)-2-(2'-amino-1,1'- biphenyl)]palladium( II)methanesulfonate (“tBuXPhos-Pd-G3”), (2-Dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)[2- (2'-amino-1,1'-biphenyl)] palladium(II) methanesulfonate (“RuPhos-Pd-G3”), (2-Dicyclohexylphosphine-2',4',6'-triisopropyl-1,1'-biphenyl)[2-(2'-amino-1,1 '- biphenyl)]palladium(II) methanesulfonate (“XPhos-Pd-G3”), [(2- Di-cyclohexylphosphine-3,6-dimethoxy-2',4',6'-triisopropyl- 1,1'- biphenyl)-2-(2'-amino-1,1'-biphenyl)]palladium(II) methanesulfonate (“BrettPhos-Pd-G3”), [(2-{Bis[3,5-bis(trifluoromethyl)phenyl ]phosphine-3,6-dimethoxy-2',4',6'-triisopropyl-1,1'-biphenyl)-2-(2'-amino-1,1'-biphenyl)]palladium(II) methanesulfonate ( “JackiePhos-Pd-G3”), and combinations thereof.

[157] PEPPSI-SIPr and the like are also suitable catalysts.

[158] In particular the catalyst can be Pd2(dba)3, an Xphos-paladacycle, Pd(PPh3)4, and combinations thereof, for example. In one aspect the catalyst comprises Xphos-paladacycle. In another aspect, the catalyst is Pd(PPh3)4.

[159] The cross-linking reaction can proceed in the absence of a base. The cross-linking reaction may include a suitable base (e.g., K3PO4, CsF, and/or Cs2CO3). In one aspect, the cross-linking reaction includes Cs2CO3. In another aspect, the cross-linking reaction includes K3PO4. The base may be present in an amount that results in good conversion (e.g., 1.5 equivalent).

[160] When the organometallic compound is a boronic acid or ester, the solvent can be an anhydrous aprotic solvent. Examples of suitable solvents include dioxane, toluene, tetrahydrofuran (“THF”), 2-MeTHF, and combinations thereof. The solvent, 2-MeTHF, can produce the intermediate in high yield. Although 1-butanol/water is a common solvent for metal-catalyzed cross-linking reactions, it is not optimal for the formation of the intermediate described here. In one example, 1-butanol/water caused a reduction in CF of the product, probably because butanol serves as a hydride source, and the cross-linking of a second pyrazole at position 2 of the pyridine ring, which indicates that oxidative insertion can occur at the C-F bond.

[161] When the organometallic compound includes a boronic acid or a boronic ester, a phase transfer catalyst (“PTC”) can be included in the reaction mixture. For example, a phase transfer catalyst can be selected from quaternary salts (e.g., chlorides, bromides, hydrogen sulfates, iodides, ammonium salts, and phosphonium salts) and crown ethers. In one aspect the phase transfer catalysts may be a quaternary ammonium or phosphonium salt. In another aspect, the phase transfer catalyst may be a crown ether.

[162] Suitable quaternary ammonium salts include tetramethylammonium bromide, tetramethylammonium chloride, tetramethylammonium hexafluorophosphate, tetramethylammonium hydroxide pentahydrate, tetramethylammonium hydroxide, tetramethylammonium hydroxide, tetramethylammonium iodide, tetramethylammonium nitrate, tetramethylammonium perchlorate, tetramethylammonium tetrafluoroborate, chloride (1) -Hexyl)trimethylammonium, phenyltrimethylammonium bromide, phenyltrimethylammonium chloride, phenyltrimethylammonium iodide, phenyltrimethylammonium methosulfate, benzyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzyltrimethylammonium hexafluorophosphate, benzyltrimethylammonium hydroxide, benzyltrimethylammonium iodide, benzyltrimethylammonium bromide ( 1- Butyl)triethylammonium, (1-Octyl)trimethylammonium bromide, tetra-n-propylammonium bromide, tetra-n-propylammonium chloride, tetra-n-propylammonium hydrogen sulfate, tetra-n-propylammonium hydroxide, tetra-n-propylammonium iodide, phenyltriethylammonium iodide, methyltri-n-butylammonium bromide, methyltri-n-butylammonium chloride, (1-Decyl)trimethylammonium bromide, benzyltriethylammonium bromide, benzyltriethylammonium chloride, benzyltriethylammonium hydroxide, benzyltriethylammonium tetrafluoroborate, (1- Dodecyl)trimethylammonium, (1-dodecyl)trimethylammonium bromide, Benzyltri-n-propylammonium chloride, tetra-n-butylammonium acetate, tetra-n-butylammonium acetate, tetra-n-butylammonium bromide, tetra-n chloride -butylammonium, tetra-n-butylammonium chloride, tetra-n-butylammonium hexafluorophosphate, tetra-n-butylammonium hydrogen sulfate, tetra-n-butylammonium hydroxide, tetra-n-butylammonium hydroxide, tetra-n-butylammonium hydroxide n-butylammonium, tetra-n-butylammonium hydroxide, tetra-n-butylammonium iodide, tetra-n-butylammonium nitrate, tetra-n-butylammonium perchlorate, tetra-n-butylammonium perchlorate, tetra-n-phosphate butylammonium, tetra-n-butylammonium sulfate, trifluoromethane-tetra-n-butylammonium sulfate, (1-tetradecyl)trimethylammonium bromide, (1-tetradecyl)trimethylammonium chloride, (1-Hexadecyl)trimethylammonium bromide, Ethyl(1 -hexadecyl)dimethylammonium, tetra-n-pentylammonium iodide, benzyltri-n-butylammonium bromide, benzyltri-n-butylammonium chloride, benzyltri-n-butylammonium iodide, (1-Hexadecyl)pyridinium bromide monohydrate, (1-Hexadecyl)pyridinium, di-n-decyldimethylammonium bromide, tetra-n-hexylammonium bromide, tetra-n-hexylammonium hydrogen sulfate, tetra-n-hexylammonium iodide, tetra-n-hexylammonium perchlorate, di-n-dodecyldimethylammonium, tetra-n-heptylammonium bromide, tetra-n-heptylammonium iodide, tetra-n-octylammonium bromide, dimethyldistearylammonium chloride, tetra-n-dodecylammonium iodide, tetraoctadecylammonium bromide.

[163] In one aspect tetrabutylammonium bromide (“TBAB”) can be used. In another aspect, tetra-n-butylammonium phosphate can be used. In yet another aspect, di-n-decyldimethylammonium bromide can be used.

[164] Suitable phosphonium salts include, but are not limited to, bis(triphenylphosphoranylidene)-ammonium chloride, (1-Hexadecyl)tri-w-butylphosphonium bromide, tetra-n-butylphosphonium bromide, tetraphenylphosphonium bromide, tetraphenylphosphonium chloride , tetraphenylphosphonium hexafluoro-antimonate, tetraphenylphosphonium iodide, tetraphenylphosphonium tetrafluoroborate, (triphenylmethyl)triphenylphosphonium chloride.

[165] Adding a catalytic amount of a PTC to the reaction mixture can consistently increase the reaction yield and consistently consume the starting material. For example, 5 mol of TBAB can be added to the reaction. Without being bound by any particular theory, PTC increases the solubility of phosphate in 2-MeTHF, and thus increases the concentration of active boronate, which accelerates transmetalation to palladium. The bromide counterion for TBAB may also play a role in improving reaction conditions. In one example, when a PTC was not added to the reaction mixture, the product yield was less than 50%.

[166] When the organometallic compound is a boronate, the solvent may include water and an alcohol. Examples of suitable alcohols include 1-butanol, 2-butanol, and the like. In one aspect the alcohol is 1-butanol. In one aspect, the alcohol is 2-butanol.

[167] The temperature may be below the reflux temperature of the reaction mixture. For example, the temperature may be in a range of about 60°C to 80°C, or 65°C to 75°C (e.g., 70°C). In one example, when the temperature was increased above 70°C or 80°C, the amount of catalyst that precipitated from the reaction increased, decreasing its lifetime. Compounds in the reaction solution can be stable at 80°C for up to about 24 hours. Extended heating, however, may reduce the amount of halide or triflate starting material in the upper space due to the boiling point of this reactant.

[168] In one type of embodiment, the intermediate can be formed by mixing 5-chloro-2,3-difluoropyridine (for example, about 1 equivalent with (e.g., about 0.9 equivalent) in an alcohol/water broth (e.g., 2-BuOH/water), e.g., at 20°C. The resulting boronate broth can be slowly added to a solution containing a palladium catalyst (e.g., about 0.004 equivalent of an Xphos-paladacycle) and an alcohol (e.g., 2-BuOH) for 1 hour, e.g. at 80°C. Slow addition of boronate avoids an exotherm. The reaction can proceed up to about 95% conversion. In one example, attempts to obtain a conversion above 98% resulted in increased impurity. After the reaction is complete, the reaction mixture can be rinsed with an alcohol (e.g. 2-butanol).

[169] The evolution of the reaction may occur by any suitable means (e.g., extraction). When evolution is extractive, it can occur in a toluene/2-butanol solution at a temperature above 40°C, for example, 50°C, 60°C, or 70°C. In one example, an extractive evolution at a temperature below 40°C resulted in precipitation and product loss. In one aspect, the evolution may include adding NaHSO3 solution to the reaction mixture. In another aspect, developments may include the use of thioglycolic acid. In another aspect, Celite can be used after NaHSO3 treatment to reduce the palladium content.

[170] After evolution, the desired intermediate can be isolated by crystallization. The evolution solvent can be exchanged for 2-butanol, and heptane can be added to the broth at a temperature in a range of 20°C to 50°C, for example. The temperature of the resulting broth can be increased (e.g., in a range of 90°C to 100°C), and the broth can be aged (e.g., for at least 15 minutes). After aging is complete, the broth can be cooled (e.g., to 20°C) for a period of time (e.g., greater than 3 hours), and the resulting crystals can be isolated and washed.

[171] In view of the teachings thereof, the cross-linking reaction can provide the desired intermediate in good yield (e.g., greater than 95% crude, greater than 87% isolated). For example, cross-linking the intermediate may result in a yield of at least about 95%, at least about 97%, or at least about 99%. The cross-linking reaction can also result in excellent purity (e.g., at least about 97%, at least about 98%, at least about 99%).

[172] Preparation of the intermediate in the synthesis of PIRH is also described in the Examples section. Step 2: Preparation of PIRH

[173] The second step in the preparation of PIRH is a nucleophilic aromatic substitution reaction between the intermediate and hydrazine.

[174] In this reaction, at least about 1 equivalent, or at least about 2 equivalents, or at least about 3 equivalents, or at least about 4 equivalents, or at least about 5 equivalents, or at least about 6 equivalents, or at least about 7 equivalents, or more of hydrazine can be used. In one class of embodiments, at least about 3 equivalents, or at least about 4 equivalents, or at least about 5 equivalents, or at least about 6 equivalents of hydrazine are used.

[175] Hydrazine serves as a reagent and as a base for the developed HF. Therefore, at least two equivalents of hydrazine can be used. Adding excess hydrazine to the reaction mixture leads to acceleration of the reaction rate. In one example, when 6 equivalents of hydrazine were used instead of 3 equivalents, the reaction time decreased from 6 hours to 3 hours, with no change in the product purity profile.

[176] The temperature of the nucleophilic aromatic substitution reaction may be greater than 70°C (e.g., at least 70°C, at least 80°C, at least 90°C, at least 100°C, at least 110° W). A lower temperature can increase the reaction time. In one example, decreasing the reaction temperature from 100°C to 80°C resulted in an increase in reaction time from 4 to 10 hours. The intermediate has poor solubility in water, which can lead to long reaction times at lower temperatures. In one example, no reaction occurred at room temperature.

[177] Any suitable solvent can be used for the nucleophilic aromatic substitution reaction. The solvent may include, for example, water, alcohol, and combinations thereof. The alcoholic solvent may include methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, and combinations thereof. In one aspect the solvents are selected from methanol, water, and combinations thereof. Carrying out the reaction in water is practical and safe.

[178] After the end of the reaction, the desired PIRH can crystallize directly from the reaction mixture. The resulting PIRH product is stable when stored at room temperature and protected from light and air.

[179] The method for preparing PIRH disclosed herein can provide PIRH in good yield (e.g., at least about 90%, at least about 95%, at least about 97% yield, at least about 99 %), and excellent purity (e.g., at least about 97%, at least about 99%, at least about 99.5%, or at least about 100%).

[180] The preparation of PIRH is also described in the Examples section. Alternative methods for the synthesis of PIRH are known in the art (see, e.g., PCT Publication WO

[181] 2013/38362 on page 78-79, which is incorporated herein in its entirety by reference).

NAPH PREPARATION

[182] Another aspect of the disclosure provides methods for preparing 3-(2-methoxyethoxy)-1,6-naphthyridin-5((5H)-one (“NAPH”). As described above, NAPH is one of three materials starting materials used to prepare Compound A.Method 1

[183] Provided herein is a method of making NAPH prepared from methylnicotinate (commercially available, e.g., from SigmaAldrich), 1,3,5-triazine, and methoxyethanol in two steps. First, methylnicotinate is condensed with 1,3,5-triazine in the presence of a base to generate a naphthyridinone intermediate. Step 1: wherein R3 is Cl, Br, or I and R4 is alkyl, including, but not limited to, Me, Et, n-Pr, or n-Bu.

[184] The condensation reaction solvent can be any suitable solvent. For example, the solvent may include any polar aprotic solvent, including, without limitation, one or more of dimethyl sulfoxide and dimethylacetamide.

[185] The base may be any suitable strong base. For example, the base may be selected from CS2CO3, KOtBu, K3PO4, K2CO3, and combinations thereof. The reaction of the base with methylnicotinate and triazine is exothermic. The addition method can be used to control the exotherm. For example, a gradual or portionwise addition (e.g., in drops) of a solution of both starting materials into a broth of the base can suppress the exotherm.

[186] The condensation reaction can occur at any suitable temperature. For example, the reaction may occur at a temperature in a range of about 15°C to 100°C, 20°C to 95°C, 30°C to 90°C, 40°C to 85°C, or 50°C. °C to 80°C.

[187] The condensation reaction produces naphthyridinone, an advantageously stable compound, which can be isolated as a beige solid. In view of the teachings thereof, the synthesis of naphthyridinone can be in high yield (e.g., 80-95% isolated) with good purity (e.g., greater than 90% by weight).

[188] Second, after the naphthyridinone intermediate is formed, it is subsequently treated with a 2-methoxyethanol salt in the presence of a catalyst to generate NAPH.Step 2:

[189] The solvent of the etherification reaction can be any suitable solvent. For example, the solvent will be an ether solvent having a boiling point greater than about 85°C. For example, the solvent may be selected from the group consisting of 2-methoxyethanol, diglyme, dioxane, and combinations thereof. In one aspect, the solvent may be pure 2-methoxyethanol. In another aspect, the solvent may be dioxane.

[190] The basis may be any suitable basis. For example, the base may be selected from KH, NaH, LiH, KOiBu, NaOiBu, LiOiBu, BuLi, HexLi, Cs2CO3, lithium bis(trimethylsilyl)amide (“LiHMDS”), sodium bis(trimethylsilyl)amide (“NaHMDS”) , potassium bis(trimethylsilyl)amide (“KHMDS”), lithium diisopropylamide (“LDA”), lithium tetramethylpiperidine (“LiTMP), LiOH, NaOH, KOH, CsOH, and combinations thereof. strong, for example, one or more of CS2CO3, LiOtBu, LiHMDS, and KOtBu.

[191] The etherification reaction can occur at any suitable temperature. For example, the reaction may occur at a temperature in a range of about 50°C to 130°C, 80°C to 120°C, or 95°C to 115°C.

[192] The copper (I) catalyst can be any suitable copper (I) catalyst. The Cu(I) catalyst can be used with or without a ligand. For example, suitable catalysts include, but are not limited to, CuBr, CuBr-DMS, Cu(OAc), Cu(OTf), and CuI. An iodine-free catalyst is more preferable for maintaining stereoselectivity in the subsequent alkylation step (to form NAPA). When the catalyst comprises a linker, suitable linkers include, but are not limited to, 1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline.

[193] The etherification reaction produces NAPH, an advantageously stable compound, which can be isolated as a crystalline solid. The resulting NAPH can be purified by any suitable purification method, for example, by crystallization, as described in further detail in the Examples section. NAPH is thermally stable up to at least 100°C, and is stable to acids and bases. Synthesis of NAPH using Method 1 below can have an isolated yield of at least about 65%, 75%, 85%, or 95%, for example. The yield can be affected by impurities that poison the Cu(I) catalyst in Step 2. The purity of NAPH can be at least about 90%, 95%, or 97%, for example. The purity of NAPH is affected by residual Cu(I) catalyst and water. Residual copper can be removed with the use of a Cu(I) scavenger, for example, N-(2-hydroxyethyl)ethylenediamine triacetic acid trisodium salt (HEDTA). Cu(I) scavenging can be aided by the presence of or introduction of a source of reactive oxygen, e.g. air.Method 2

[194] The disclosure provides a method of making NAPH from a protected N-(3-formyl-4-amino-2-alkoxy)pyridine and 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate in two steps. First, a protected N-(3-formyl-4-amino-2-alkoxy)pyridine is mixed with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate and base under conditions sufficient to form a naphthyridine of Formula (III). Step 1: where R8 is alkyl and PG is a protecting group.

[195] The protecting group can be any suitable protecting group, including, without limitation, PivCl, PivBr, or Piv anhydride. R8 can be any alkyl such that OR8 is an ortho-directing metallating group. For example, R8 can be any of the C1-4 alkyl groups.

[196] A protected N-(3-formyl-4-amino-2-alkoxy)pyridine can be prepared by converting 2-alkoxy-pyridin-4-ylamine to a protected amine followed by directed ortho-lithiation in THF or MeTHF . The directed ortho-lithiation is then quenched with, for example, DMF or N-formylmorpholino to generate the corresponding substituted formyl pyridine. The amide can then be hydrolyzed with excess base and converted to the corresponding naphthyridine ether with a methoxyethoxy acetaldehyde bisulfite adduct.

[197] The protected amine can be formed by mixing 2-alkoxy-pyridin-4-ylamine with a protecting group selected from, for example, a compound of Formula (IV) to form an N-(2- a! c .oxy ni ri di n-4-yl)pivalamide: wherein R5 is Cl, Br or OC(O)alkyl and wherein alkyl is Me, Et, Pr, iPr, n-Bu, sec-Bu or i-Bu.

[198] The protecting group can be added at any suitable temperature, for example, at a temperature in a range of about -30°C to about 50°C, for example 0°C. The yield of the protected aminopyridine may be at least about 85%, at least about 90%, or at least about 95%, for example. The purity of the protected aminopyridine may be at least about 90%, at least about 80%, or at least about 60%, for example.

[199] Similarly, ortho-lithiation can be carried out at any suitable temperature. For example, ortholithiation may proceed at temperatures of 25°C or less, for example a temperature in a range of about -50°C to about 25°C, or about -30°C to about - 10°C. The lithium reagent can be selected from n-hexyl lithium, n-butyl lithium, s-butyl lithium, lithium bis(trimethylsilyl)amide (“LiHMDS”), lithium diisopropyl amide (“LDA”), lithium tetramethylpiperidine (LiTMP), or combinations of these, for example.

[200] Quenching of the ortho-lithiation can proceed at any temperature suitable for providing the substituted formyl pyridine, for example, a temperature in a range of about -78 ° C to 25 ° C, for example, -10 ° C. The yield of the substituted formyl pyridine may be at least about 80%, at least about 85%, or at least about 90%, for example. The purity of the substituted formyl pyridine may be at least about 95%, at least about 60%, or at least about 30%, for example.

[201] Suitable bases for hydrolysis and thus deprotection of the amine in the formyl substituted pyridine can be any strong base, for example, including, without limitation NaOH, KOH, K3PO4, LiOH, CsOH, and RbOH. Without wishing to be bound by theory, it is believed that strong acids such as HCl should be suitable for amine hydrolysis and deprotection.

[202] Mixing of the protected N-(3-formyl-4-amino-2-alkoxy)pyridine and the bisulfite adduct can occur in any suitable solvent. Suitable solvents include water-soluble solvents. Suitable solvents also include base-stable solvents. For example, methanol, ethanol, isopropanol, acetonitrile, tetrahydrofuran, dioxane, 2-methoxyethanol, i-BuOH, 2-BuOH, trifluoroethanol, water, and combinations thereof are suitable solvents.

[203] The bisulfite adduct can be added at any suitable temperature to convert substituted formyl pyridine to the corresponding naphthyridine ether. For example, suitable temperatures include temperatures in a range of about 40°C to about 90°C, e.g., about 40°C, about 50°C, about 60°C, about 70°C, about 80°C, or about 90°C. High conversion can be achieved by slowly adding the bisulfite adduct. The bisulfite adduct is provided in an amount in a range of about 1 equivalent to about 5 equivalents, about 1 equivalent to about 4 equivalents, about 1 equivalent to about 3 equivalents, about 1 equivalent to about 2 equivalents, or about 1.6 equivalents, for example.

[204] Optionally, the naphthyridine of Formula (III) can be formed by mixing a protected N-(3-formyl-4-amino-2-alkoxy)pyridine with 2-methoxyethoxyacetaldehyde instead of the bisulfite adduct. However, 2-methoxyethoxyacetaldehyde is not as stable as the bisulfite adduct. When 2-methoxyethoxyacetaldehyde is used, mixing can occur in any suitable solvent. Suitable solvents include water-soluble solvents. Suitable solvents also include base-stable solvents. For example, methanol, ethanol, isopropanol, and acetonitrile are suitable solvents.

[205] 2-Methoxyethoxyacetaldehyde can be added at any suitable temperature to convert substituted formyl pyridine to the corresponding naphthyridine ether. For example, suitable temperatures include temperatures in a range of about 40°C to about 90°C, e.g., about 40°C, about 50°C, about 60°C, about 70°C, about 80°C, or about 90°C. 2-Methoxyethoxyacetaldehyde is supplied in an amount in a range of about 1 equivalent to about 5 equivalents, about 1 equivalent to about 4 equivalents, about 1 equivalent to about 3 equivalents, about 1 equivalent to about 2 equivalents, or about 1.6 equivalents, for example.

[206] Second, after naphthyridine of Formula (III) is formed, it is subsequently treated with a strong acid under conditions sufficient to generate NAPH.Step 2: wherein R is alkyl, for example, any C1-4 alkyl.

[207] The acid may suitably be any strong acid. For example, strong acids may include inorganic acids, including, but not limited to, HCl, HBr, and H2SO4, and organic acids, including, but not limited to, methanesulfonic acids (e.g., trifluoromethanesulfonic acid), trifluoroacetic acid, and tolylic. The acid may be added in any amount suitable to convert naphthyridine of Formula (III) to NAPH. For example, the acid may be supplied in an amount in a range of about 1 equivalent to about 10 equivalents, about 1 equivalent to about 8 equivalents, about 1 equivalent to about 6 equivalents, about 1 equivalent to about 4 equivalents, about 1 equivalent to about 3 equivalents, about 1 equivalent to about 2 equivalents, about 1 equivalent to about 1.5 equivalents, or about 1.2 equivalents.

[208] The acidification temperature can be any temperature suitable for converting naphthyridine of Formula (III) to NAPH. For example, the temperature may be in a range of about 50°C to about 100°C, or about 50°C to about 80°C, or about 55°C to about 75°C, or about 65°C.

[209] The resulting NAPH can be purified by any suitable purification method, for example, by crystallization, as described in greater detail in the Examples section. For example, NAPH can be crystallized with a base. Suitable bases include inorganic bases, including, without limitation, NaOH, KOH, K2CO3, and NaHCO3, and organic bases, including, without limitation, EtN.

[210] In view of the teachings thereof, the synthesis of NAPH by Method 2 can have an isolated yield of at least about 80%, at least about 90%, or at least about 95%, for example. The purity of NAPH may be at least about 80%, at least about 30%, or at least about 10%, for example.

[211] Method 2 may be advantageous for one or more reasons and may avoid one or more of the disadvantages of Method 1. For example, there may be one or more of the following advantages: Method 2 may produce highly pure NAPH, there may be no heavy metal contamination, NAPH may have <0.3% organic impurities, NAPH may be easy to dry (dry NAPH critical for downstream synthesis of NAPA), starting materials are readily available from commercial sources, there may be no highly toxic material involved in the process, and the process can be very robust and has been scaled up to more than 80 kg per batch.

[212] The preparation of NAPH is also described in the Examples section. Furthermore, methods for the synthesis of NAPH are known in the art (see, for example, Fang et al., J Am Chem Soc 132(44):15,525-7 (2010); WO 2009/091375, which is incorporated herein in its entirety by reference).

BISSULFITE ADDUCT PREPARATION

[213] Another aspect of the disclosure provides a method of making 1-hydroxy-2-(2-2-methoxyethoxy)ethane-1-sulfonate from 2-(2-methoxyethoxy)acetaldehyde with HSO3-, S2O5-, or a combination of these under conditions sufficient to form 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate.

[214] Isolated 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate is advantageously stable. For example, in contrast to the starting material 2-(2-methoxyethoxy)acetaldehyde which is highly unstable, samples of 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate can be left exposed to the atmosphere for at least 2 years without decomposition. Furthermore, the raw materials used to produce 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate are readily available and the yield is higher than for other methods of preparing 1-hydroxy-2-(2- methoxyethoxy)ethane-1-sulfonate.

[215] 2-(2-methoxyethoxy)acetaldehyde can react with HSO3-, S2O52-, or a combination of these. The HSO3- and S2O52- anion can be supplied in any form, for example, having a counterion selected from Li+, K+, Na+, Me4N+, Et4N+, Bu4N+, or combinations thereof.

[216] The addition of HSO3- and/or S2O52- to 2-(2-methoxyethoxy)acetaldehyde can be carried out at any suitable temperature. For example, the addition of HSO3- and/or S2O52- can be carried out at a temperature in a range of about -10°C to 50°C.

[217] Suitable solvents for the addition of HSO3- and/or S2O52-, to 2-(2-methoxyethoxy)acetaldehyde include, for example methoxyethanol, water, methanol, ethanol, and combinations thereof (e.g. methoxyethanol, water/methanol , and water/ethanol).

[218] In view of the teachings thereof, the yield of production of 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate may be at least about 50%, at least about 60%, at least about 70%, or at least around 80%, for example. The 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate formed by this method may have a purity of at least about 40%, at least about 50%, or at least about 60% as a solution in H2O, with water making up the majority of the remaining weight.

[219] In embodiments of the disclosure, 2-(2-methoxyethoxy)acetaldehyde can be formed by oxidizing 2-(2-methoxyethoxy)-1-ethanol with an oxidizing agent.

[220] The oxidizing agent can be selected from oxalyl chloride, pyridinium chlorochromate (“PCC”), pyridinium dichromate (“PDC”), or dimethyl sulfoxide (“DMSO”) activated with a pyridine trioxide sulfur complex, for example. Oxidation can occur via a Swern oxidation, for example with oxalyl chloride, DMSO and an organic base. Swern oxidation is well known in the art.

[221] When the oxidation also includes a base, for example, a Swern oxidation, the base can be selected from organic bases, including, without limitation, triethylamine, N,N-diisopropylethylamine (DIPEA), N-methylmorpholino, and combinations of these.

[222] Suitable solvents for oxidation include, but are not limited to, high-boiling solvents (e.g., boiling point > 100°C), for example methoxyethanol.

[223] Using the oxidation method, the yield of 2-(2-methoxyethoxy)acetaldehyde can be at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99%. Furthermore, the purity of 2-(2-methoxyethoxy)acetaldehyde may be at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, at least about 85%, at least about 90%, at least about 95%.

[224] In embodiments of the disclosure, 2-(2-methoxyethoxy)acetaldehyde can be formed by: (1) mixing methoxyethanol with a compound of Formula (V): and a strong base, followed by hydrolysis to form 2-(2-methoxyethoxy)acetaldehyde; wherein R6 is selected from the group consisting of Cl, Br, I, and cyclic diol protecting groups, e.g., ethylene glycol and 1,3-propanediol, and R7 is C1-4 alkyl, each R7 is independently CH3, CH2CH3, or CH2CH2CH3.

[225] The reaction proceeds via an SN2 mechanism. This method is advantageous because it provides a higher yield as the oxidation process does not require equipment to sustain cryogenic procedures such as Swern oxidation.

[226] The strong base may be present in an amount in a range of about 1 equivalent to about 1.5 equivalents, or about 1.2 equivalents, for example. Any suitable strong base can be used, for example, one or more of NaH, LiH, LiOt-Bu, BuLi, hexLi, NaOt-Bu, KOt-Bu, KH and LiOH.

[227] Mixing can occur at any temperature suitable to promote the SN2 reaction. Suitable temperatures may be in a range of about 100°C to about 120°C, or about 110°C, for example.

[228] Hydrolysis to form 2-(2-methoxyethoxy)acetaldehyde occurs under acidic conditions. Suitable acids include, but are not limited to, strong acids, including inorganic acids, including, without limitation, HCl, HBr, and H2SO4, and organic acids, including, without limitation, methanesulfonic acids and tolylic acids.

[229] Using the SN2 method, the yield of 2-(2-methoxyethoxy)acetaldehyde can be at least about 40%, or at least about 50%, or at least about 60%, or at least about about 70%, or at least about 80%, at least about 85%, at least about 90%, at least about 95%. Furthermore, the purity of 2-(2-methoxyethoxy)acetaldehyde may be at least about 80%, or at least about 85%, or at least about 90%, or at least about 95%, or at least about 97%, or at least about 99%.

[230] The preparation of the bisulfite adduct is also described in the Examples section.

EXAMPLES

[231] The following examples are provided for illustration and are not intended to limit the scope of the invention. EXAMPLE 1 Synthesis of acid naphthalene-2-sulfonate (R)-2-(3-(2-methoxyethoxy)-5- oxo-1,6-naphthyridin-6(5H)-yl)propanoic acid (NAPA) Scheme 1: Synthesis of naphthyridinone acid 2-napsilate (NAPA)

[232] NAPA was synthesized according to Scheme 1 by the following procedure. A jacket reactor (60 L) was charged with 3,000 g (1.0 equivalent) of 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one and 4,646 g (2.0 equivalent) of magnesium tert-butoxide. 12 L (4.0 Vol) of tetrahydrofuran was added to the reactor and an N2 purge and stirring were started. 2,213 g (1.5 equivalent) of S-2-bromopropionic acid were added for at least 30 minutes, controlling the addition so that the batch temperature did not rise above 30°C. The loading port was rinsed with tetrahydrofuran (0.5 Vol) after addition. The batch was then aged for at least 5 minutes at 25°C. 1,600 g (1.05 equivalent) of potassium tert-butoxide were added to the reactor in four (approximately equal) portions so that the batch temperature did not rise above 30°C. The charging port was rinsed again with tetrahydrofuran (1.5 L, 0.5 Vol). The batch temperature was adjusted to 35 ± 5°C and the batch was aged for at least 12 h.

[233] A separate 100 l reactor was charged with 6 l of 2-Metetrahydrofuran (2-MeTHF) (2.0 Vol), 8.4 l of water (1.5 Vol) and 9.08 l (4. 0 equivalents) of 6 N HCl. The mixture from the 60 l reactor was pumped into the 100 l reactor, keeping the batch temperature below 45°C.

[234] The batch temperature was then adjusted to 20 ± 5°C. the pH of the batch was adjusted with 6 N HCl (or 2 N NaOH) solution until the pH was 1.4 to 1.9. The aqueous layer was separated from the organic layer containing the product. The aqueous layer was extracted with 2-MeTHF (2 Vol), and the 2-MeTHF was combined with the product stream in the reactor. The combined organic stream was washed with 20% brine (1 Vol). The organic layer was polished-filtered through a <10 μm filter into a clean vial.

[235] In a separate vial, 1.1 equivalents of 2-naphthalene sulfonic acid hydrate was dissolved in THF (2 Vol). The solution was polished-filtered before use. THF 2-naphthalene sulfonic acid hydrate solution was added into the organic product solution in the flask for at least 2 h at 25 ± 5°C. The batch temperature was adjusted to 60 ± 5°C and the batch was aged for 1 ± 0.5 h. The batch temperature was adjusted to 20 ± 5°C for at least 2 h. The batch was filtered to collect the product. The collected filter cake was washed with THF (5.0 Vol) by displacement. The product cake was dried in a frit under vacuum/nitrogen stream until the water content was < 1% by weight by LOD.

[236] The yield of the product (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanoic acid naphthalene-2-sulfonate was 87% . Chiral purity was determined using chiral HPLC and was 98-99% ee. Purity was determined using HPLC, and was >98%.

[237] Therefore, example 1 shows the synthesis of NAPA according to the disclosure. EXAMPLE 2 Synthesis of (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl) pyridin-2-yl)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanehydrazide (HYDZ) Scheme 2: Synthesis of (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-(3-(2-methoxyethoxy)- 5-oxo-1,6-naphthyridin-6(5H)-yl)propanehydrazide

[238] HYDZ was synthesized according to Scheme 2 by the following procedure. A 60 L jacket reactor was charged with 2,805.0 g (1.0 equivalent) of (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H) acid )- il)propanoic 2-napsilate (NAPA) and N,N-dimethylacetamide (DMAC) (4.6 ml of DMAC per gram of NAPA). Agitation and an N2 wash were initiated. 1.05 equivalent of N,N-diisopropylethylamine (DIPEA) was added keeping the batch temperature below 35°C. Initially NAPA dissolves. A white precipitate formed during aging, but the precipitate did not have any impact on the performance of the reaction. 2,197 g (1.10 equivalents) of 3-fluoro-2-hydrazinyl-5-(1-methyl-1H-pyrazol-4-yl)pyridine (PIRH) were added to the batch. The batch temperature was adjusted to 10 ± 5°C. 2,208 g (1.2 equivalent) of N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) was added in four (approximately equal) portions for at least 1 h (range about 20 minutes per portion) to 10 ± 5°C.

[239] The batch was aged until the amide conversion was carried out. If amide conversion was not accomplished within 2 h, more EDC was added until the desired conversion was achieved. Once achieved, the batch was heated to 55°C until the solution was homogeneous. The batch was filtered through a <20 μm in-line filter in a reactor. The flask and filter were rinsed with DMAC (0.2 ml DMAC/g NAPA). The batch temperature was adjusted to 45 ± 5°C.

[240] The reactor was charged with a seeding broth of (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-( 3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanehydrazide (HYDZ) (0.01 equivalent) in water (0.3 ml/g).

[241] The batch was aged at 50 ± 5°C for at least 30 minutes. The batch temperature was adjusted to 20 ± 5°C for at least 2 h. The batch was aged at 20 ± 5°C for at least 30 minutes. 2.90 ml of water per g was added at 25 ± 5°C for at least 2 h. The batch was aged at 20 ± 5°C for at least 1 h. the batch broth was filtered to collect the product. The product was washed with 30% DMAC/H2O (0.5 Vol) by displacement. The product cake was washed with water (3 Vol) by displacement. The product cake was dried in the frit under vacuum/nitrogen stream until the water content was < 0.2% by weight as determined by Karl Fischer (KF) titration. The product was a white, crystalline solid. The yield was about 83-84%. The ee was measured by HPLC and was >99.8% ee. Purity was determined by HPLC and was >99.8 LCAP (LC area percent purity).

[242] Therefore, example 2 demonstrates the synthesis of HYDZ in accordance with the disclosure. EXAMPLE 3 Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-) hydrochloride salt pyrazol-4-yl)-[1,2,4]triazol[4,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)- ona (compound A-HCl) - Route 1 Scheme 3 Route 1 - Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4, 3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one

[243] (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-) hydrochloride salt a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (Compound A-HCl) was synthesized according to Scheme 3, route 1 by the following procedure. A 15 L reactor, reactor 1, was charged with 750 g of HYDZ and the jacket reactor temperature was set at 20 ± 5°C. A nitrogen purge was initiated in Reactor 1 and condenser coolant (at 5 ± 5°C) was started. Acetonitrile (3.4 L, 4.5 Vol) was added to Reactor 1 and stirring was started. 420 g (2.5 equivalents) of 2,6-lutidine were added to the reactor.

[244] A solution of diphenylphosphinyl chloride Ph2P(O)(Cl) was prepared by combining 850 g (2.3 equivalents) of Ph2P(O)(Cl) and 300 g of acetonitrile in a suitable container. The contents of the Ph2P(O)(Cl) solution were added to Reactor 1. The temperature was adjusted for 60 ± 30 minutes until the batch reflux temperature (approximately 85°C) was reached. The reaction was stirred for 14 ± 6 h. The batch temperature was reduced to 75 ± 5°C and the batch was taken for IPT analysis. The expected result was < 2% HYDZ remaining. If the target was not reached, heating at reflux temperature was continued for 9 ± 6 h. Sampling, analysis, and heating were repeated until a satisfactory conversion assay result was obtained (<10% HYDZ was considered satisfactory, <1% was actually achieved). The final sample was analyzed for optical purity by HPLC, and was >99.5% ee.

[245] A K2CO3/KCl (5.0 Vol) quench solution was prepared in advance by combining 555 g (3.1 equivalents) of potassium carbonate with 335 g (2.9 equivalents) of potassium chloride and 3,450 g of water in a suitable container. The quenching solution was added to Reactor 1 for at least 15 minutes, maintaining the batch temperature at 60 ± 5°C. Once the aqueous base reacted with excess acid, some bubbling (CO2) occurred. 3.0 L (4.0 Vol) of toluene was added to Reactor 1 at 65 ± 5°C. a sample from the batch was taken for IPT analysis. The lower (aqueous) phase of the sample was analyzed using a pH probe (glass electrode). The pH was acceptable if in the pH range 8-11. The upper (organic) phase of the sample was analyzed by HPLC.

[246] The batch was stirred for 20 ± 10 minutes at 65 ± 5°C. Agitation was stopped and the suspension was allowed to rest for at least 20 minutes. The aqueous phase was drained from Reactor 1 via a closed transfer into a suitable inert container. The remaining organic phase was drained from Reactor 1 via a closed transfer to a suitable inert container. The aqueous phase was transferred back to Reactor 1.

[247] An aqueous wash was prepared in advance by combining 2.3 l (3.0 Vol) of acetonitrile and 2.3 l (3.0 Vol) of toluene in a suitable container. The aqueous wash was added to Reactor 1. The batch was stirred for 20 ± 10 minutes at 65 ± 5°C. Agitation was stopped and the suspension was allowed to rest for at least 20 minutes. The lower (aqueous) phase was drained from Reactor 1 via a closed transfer into a suitable inert container. The organic phase was drained from Reactor 1 through a closed transfer to the inert container containing the first organic cut. The combined mass of the two organic cuts was measured and the organic cuts were transferred back to Reactor 1. Stirring was started and the batch temperature was adjusted to 60 ± 10°C. The batch sample was taken and tested for Compound A content by HPLC. The contents of Reactor 1 were distilled under vacuum (about 300-450 mmHg) to approximately 8 volumes maintaining the batch temperature of 60 ± 10°C and a jacket temperature below 85°C. The final volume was between 8 and 12 volumes.

[248] Nitrogen cleaning in Reactor 1 was resumed and the batch temperature adjusted to 70 ± 5°C. The batch sample was taken to determine the toluene content by GC. If the result was not within 0-10% area, distillation was continued and concomitantly an equal volume of 2-propanol, up to 5 volumes, was added to maintain constant batch volume. Sampling, analysis, and distillation were repeated until the toluene content was in the 0-10% area window. After distillation was complete, 540 g (450 ml, 3.5 equivalents) of hydrochloric acid was added to Reactor 1 for 45 ± 15 minutes maintaining the batch temperature at 75 ± 5°C.

[249] A seeding suspension of Compound A-HCl was prepared in advance by combining 7.5 g of Compound A-HCl and 380 ml (0.5 Vol) of propanol in a suitable container. The seeding suspension was added to Reactor 1 at 75 ± 5°C. The batch was stirred for 60 ± 30 minutes at 75 ± 5°C. The batch was cooled to 20 ± 5°C for 3 ± 1 h. The batch was stirred for 30 ± 15 minutes at 20 ± 5°C. 2.6 l (3.5 Vol) of heptane was added to the batch for 2 ± 1 hours. The batch was then stirred for 60 ± 30 minutes at 20 ± 5°C. The batch sample was taken and filtered for IPT analysis. The filtrate was analyzed for Compound A-HCl. If the amount of Compound A-HCl in the filtrate was greater than 5.0 mg/ml the batch was kept at 20°C for at least 4 h before filtration. If the amount of Compound A-HCl in the filtrate was in the range of 2-5 mg.ml, the contents of Reactor 1 were filtered through a PTFE or PP filter fabric <25 μm, sending the filtrate to a suitable container.

[250] A first cake wash was prepared in advance by combining 1.5 l (2.0 Vol) of 2-propanol and 1.5 l (2.0 Vol) of heptane in a suitable container. The first cake wash was added to Reactor 1 and the contents were stirred for approximately 5 minutes at 20 ± 5°C. The contents from Reactor 1 were transferred to the cake and filter. A second cake wash of 3.0 (4.0 Vol) heptane was added to Reactor 1 and the contents were stirred for approximately 5 minutes at 20 ± 5°C. The contents from reactor 1 were transferred to the cake and filter. The wet cake was dried under a stream of nitrogen and vacuum until the heptane content was less than 0.5% by weight as determined by GC. The dry yield was 701 g, 85% as a yellow powder. The dried material was analyzed for chemical purity and potency by HPLC and for residual solvent content by GC. The isolated product was 88.8% Compound A-HCl, having 99.8% ee and 0.6% water.

[251] Therefore, example 3 shows the synthesis of Compound A-HCL according to the disclosure. EXAMPLE 4 Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3] hydrochloride salt -a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (compound A-HCl) - route 2 Scheme 4: Route 2 - Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4] hydrochloride ,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one

[252] Hydrochloride salt (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-a ]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one was synthesized according to Scheme 4, route 2, by the following procedure. A clean, dry 60 L reactor was fitted with a reflux condenser, nitrogen inlet, and discharged to a scrubber (Reactor 1). The temperature of Reactor 1 was adjusted to 20°C. A scrubber was added to the Reactor 1 vent, and aqueous bleach solution was charged to the scrubber. The circulating pump (commercial 5.25% NaOCl) was started. The purifier pump was turned on and cleaning of N2 in Reactor 1 was started. Reactor 1 was charged with 2,597 g (0.52 equivalents) of Lawesson reagent. Reactor 1 was then charged with 6,000 g (1.0 equivalent) of HYDZ and 30 l (5.0 vol) of acetonitrile (MeCN). Reactor 1 agitation has started. The reactor was heated to 50 ± 5°C and aged until an LC assay showed consumption of HYDZ (>99% conversion).

[253] The temperature of a second clean and dry reactor, Reactor 2, was set at 50°C. The contents from reactor 1 were transferred to reactor 2 through a 5 micron in-line filter. Reactor 1 was rinsed with MeCN, and the rinse was transferred through the in-line filter to reactor 2. Reactor 2 was charged with toluene. (31.7 kg)

[254] In a separate container a 16.7% K2CO3 solution was prepared by adding 7,200 g of K2CO3 and 36 l of water to the container and shaking the container until all the solid was dissolved. Half of the K2CO3 solution was added to reactor 2 for at least 10 minutes. The batch temperature of reactor 2 was set at 50 ± 5°C. The batch in reactor 2 was stirred at 50 ± 5°C for at least 1 h. Agitation was stopped and the batch in Reactor 2 underwent phase separation. The aqueous phase was removed. The remaining contents of the K2CO3 solution were added to reactor 2 for at least 10 minutes. The batch temperature in reactor 2 was set at 50 ± 5°C. The batch in reactor 2 was stirred at 50 ± 5°C for at least 1 h. Agitation was stopped and the batch in reactor 2 underwent phase separation. The aqueous phase was removed.

[255] The temperature of the clean and dry reactor, Reactor 3, was set at 50°C. The contents from reactor 2 were transferred to reactor 3 through a 5 micron in-line filter. The contents of Reactor 3 were distilled under reduced pressure. Isopropyl alcohol (IPA, 23.9 kg) was charged into reactor 3 and then the batch was distilled. IPA (23.2 kg) was added again to reactor 3. The charge/distillation/charge cycle was repeated. The batch temperature in Reactor 3 was adjusted to 70 ± 15°C. Reactor 3 was then charged with DI water (1.8 l). Concentrated HCl (1015 ml) was added to reactor 3 for at least 15 minutes at 70 ± 15°C.

[256] A seed of the compound A-HCl was prepared by combining a seed and IPA in a separate container. The compound A-HCl seed was added to reactor 3 as a broth. The batch in Reactor 3 was aged at 70 ± 15°C for at least 15 minutes to ensure that the seed was maintained. The batch in Reactor 3 was cooled to 20 ± 5°C for at least 1 h. Heptane (24.5 kg) was added to Reactor 3 at 20 ± 5°C for at least 1 h. The batch was aged at 20 ± 5°C for at least 15 minutes. The contents of reactor 3 were filtered through an Aurora filter fitted with a PTFE or PP filter cloth <25 μm. The mother liquor was used to rinse reactor 3.

[257] A 50% v/v IPA/heptane solution was prepared in advance in a separate container by adding the IPA and heptane to the container and stirring. The filter cake from Reactor 3 was washed with the 50% IPA/heptane solution. If necessary, the IPA/heptane mixture, or heptane alone, can be added to reactor 3 before filtering the contents through the Aurora filter. The cake was washed with heptane. The cake was dried under nitrogen and vacuum until there was about <0.5% by weight of heptane by GC analysis. The product was analyzed for purity and assay for % by weight by achiral HPLC, for % by weight by QNMR, for water content by KF, for shape by XRD, for chiral purity by chiral HPLC, and for K and P content by elementary analysis of ICP.

[258] Compound A-HCl had a purity of 99.56% by area and 88.3% by weight in the achiral HPLC assay, and 89.9% by weight by QNMR. The water content was 0.99% by weight as determined by KF. Chiral purity was 99.9% ee as determined by chiral HPLC. The P and K content was 171 ppm and 1,356 ppm, respectively, as determined by ICP elemental analysis.

[259] Therefore, example 4 shows the synthesis of Compound A-HCl in accordance with the disclosure. EXAMPLE 5 Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)- [1,2,4]triazol[4,3-a]pyridin -3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (compound a) - route 3 Scheme 5: Route 3 - Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl- 1H-pyrazol-4-yl)-[1,2,4]triazol[4,3 -a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (compound A)

[260] (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-a]pyridin- 3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one was synthesized according to Scheme 5, route 3, by the following procedure. 0.760 g (1.6 mmol) of N'-(3-fluoro-5(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-(3-(2-methoxyethoxy)-5 -oxo-1,6-naphthyridin-6(5H)-yl)propanehydrazide (HYDZ) and 0.62 g (2.4 mmol) triphenylphosphine were taken up in 16 ml of THF. 0.31 ml (2.4 mmol) of trimethylsilyl (TMS)-azide was added, followed by addition of 0.37 ml (2.4 mmol) of DEAD, keeping the reaction temperature below 33°C. The reaction was stirred at room temperature for 50 minutes. The reaction mixture was concentrated in vacuo.

[261] The raw material was retained in dichloromethane and loaded onto silica gel. The crude material was purified via medium pressure liquid chromatography using a 90:10:1 DCM:MeOH:NH4OH solvent system. 350 mg, (48% yield) of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4 ,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one were collected as a brown solid. The (S) isomer was also collected. The product was 97% pure by HPLC.

[262] Therefore, Example 5 shows the synthesis of enantiomerically pure Compound A in accordance with the disclosure. EXAMPLE 6 Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)- [1,2,4]triazol[4,3-a]pyridin -3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (compound A) and the hydrochloride salt - route 3 Scheme 6: Route 3 - Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3 -a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (compound A) and the hydrochloride salt

[263] (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-a]pyridin- 3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one was synthesized according to Scheme 6, route 3, by the following procedure. Benzothiazil disulfide (3.31 g, 9.97 mmol), HYDZ (4.0 g, 8.31 mmol), and a stir bar were added to a 50 ml 3-neck flask fitted with a reflux condenser with a nitrogen inlet at the top, a thermocouple and a septum. The headspace of the flask was purified with nitrogen, and the solids were suspended in MeCN (20.00 ml, 5 ml/g) under ambient conditions. The contents of the flask were heated to 50°C on a heating mantle. Finally, trimethylphosphine, solution in THF (9.97 ml, 9.97 mmol) was added dropwise by syringe pump with stirring for 1 h. An ice pack was affixed to the side of the flask in place of a reflux condenser. After about 0.5 h of addition, the resulting suspension was sampled and analyzed, showing about 99% conversion of penultimate, and about 94% of Compound A vs. benzothiazol-2-thiol (“BtSH”) adduct selectivity.

[264] After about 0.75 h of addition, the yellow reaction mixture was cooled to 0°C in an ice bath, and 30% hydrogen peroxide in water (2.037 ml, 19.94 mmol) was added in drops for 2 hours. The reaction solution was warmed to room temperature overnight.

[265] The suspension was heated to 30°C, maintained at that temperature for 3 h and then cooled to room temperature. After cooling was complete, an aliquot was filtered and the filtrate was analyzed by liquid chromatography, showing 99% Compound A vs. BtSH adduct (91% purity for Compound A overall).

[266] A Celite filtration pad of about 0.5” thickness was placed in a 50 ml disposable filter holder and moistened with toluene (32.0 ml, 8 ml/g). The reaction suspension was transferred to Celite absorbent and filtered to remove BtSH-related byproducts, washing with MeCN (2,000 ml, 0.5 ml/g). The filtrate was transferred to a 100 ml round bottom flask, and treated with 30 ml (7.5 Vol) of an aqueous quench solution consisting of sodium bicarbonate (7.5 ml, 8.93 mmol) and thiosulfate. of sodium (3.75 ml, 4.74 mmol) at about 5% by weight of salt. The suspension was stirred for about 15 min and then the layers were separated. Once the layers were cut, the aqueous waste stream was analyzed by LC, showing 8% loss. The organic stream was similarly analyzed, showing 71% assay yield, implying around 20% loss to the waste cake.

[267] The organic cut was transferred to a 50 ml 3-neck round bottom flask with magnetic stir bar, thermocouple, and a shortpath distillation head with an ice-cooled receiving flask. The boiling weak contents were distilled at 55°C and pressure of 300 torr (39.99 Kpa). The volume was reduced to 17 ml. Distillation was continued at constant volume with concomitant infusion of IPA (about 75 ml). The resulting tin suspension was filtered into a warm flask and water (0.8 ml) was added. The solution was heated to 80°C. After this temperature was reached, hydrochloric acid, 37% concentrate (0.512 ml, 6.23 mmol) was added, and the solution was seeded with about 30 mg (about 1% by weight) of Compound A-salt. HCl. The seed was left to rest for 15 minutes. Next, the suspension was cooled to 20°C for 2 h. Finally, heptane (17 ml, 6 Vol) was added for 2 h by syringe pump. The suspension was stirred under ambient conditions overnight.

[268] The greenish-yellow solid was filtered on a glass filter of porosity M. The wet cake was washed with 1:1 heptane/IPA (2 Vol, 5.5 ml) and then with 2 additional volumes of heptane (5 .5ml). The cake was dried by passing air. The dried cake (3.06 g, 78.5% by weight, 94 LC area% Compound A, 62% yield) was analyzed by chiral LC showing optical purity of 99.6% ee.

[269] Thus, Example 6 shows the synthesis of enantiomerically pure Compound A and its hydrochloric salt, in accordance with the disclosure. EXAMPLE 7 Recrystallization of Compound A Scheme 7: Recrystallization of Compound A

[270] Compound A-HCl was recrystallized to Compound A. A jacket reactor (60 l), Reactor 1, with a jacket temperature of 20°C was charged with 5,291 g, 1.0 equivalent of Compound A-HCl . 2 Vol (10.6 l) of IPA and 1 Vol (5.3 l) of water were added to Reactor 1 and stirring of Reactor 1 was started.

[271] An aqueous solution of NaHCO3 was prepared in advance by loading NaHCO3 (1,112 g) and water (15.87 l, 3 Vol) into a suitable container and stirring until all solids were dissolved. The prepared NaHCO3 solution was added to Reactor 1 for at least 30 minutes, keeping the batch temperature below 30°C. The batch temperature was then adjusted to about 60°C. The reaction solution was filtered by transferring the contents of Reactor 1 through an in-line filter to a second reactor, Reactor 2, having a jacket temperature of 60 ± 5°C. Reactor 2 was charged with water (21.16 l) for at least 30 minutes through an in-line filter, maintaining the batch temperature at approximately 60°C. After addition, the batch temperature was adjusted to approximately 60°C.

[272] A seed was prepared by combining Compound A seed (0.01 equivalent) and IPA/water (20:80) in a suitable container, in an amount sufficient to obtain a suspension. The seed preparation stage was carried out in advance. Reactor 2 was loaded with seed juice. The batch was aged at 55-60°C for at least 15 min. The batch was cooled to 20 ± 5°C for at least 1 h. The batch from Reactor 2 was recirculated through a wet mill for at least 1 h, for example, using a thin rotor stator at 60 Hz, having a flow rate of 4 l/min, for about 150 min.

[273] Samples of the reaction mixture were taken for particle size distribution during the milling operation. Solids were analyzed by Malvern particle size distribution (PSD) and microscopic imaging. At the end of the grinding operation, the reaction mixture sample was analyzed again. The supernatant concentration was analyzed by HPLC, and the solids were analyzed by Malvern PSD and microscopic imaging to visualize the resulting crystals.

[274] The batch temperature was adjusted to 35 ± 5°C and the batch was aged for at least 1 h. The batch was cooled to 20 ± 5°C for at least 2 h. samples of the reaction mixture were taken to determine the amount of product remaining in the supernatant. The supernatant concentration was analyzed by HPLC to target <5 mg/ml Compound A in the supernatant. Reactor 2 contents were filtered through an Aurora filter fitted with a PTFE or PP filter cloth <25 μm.

[275] A 20% v/v IPA/water solution was prepared and the reactor 2 filter cake was washed with the 20% v/v IPA/water solution. The cake was then washed with water. If necessary, the IPA/water solution, or water alone, can be added to Reactor 2 prior to filtration to flush the reactor contents. The cake was dried under moist nitrogen and vacuum until target water and residual IPA levels were reached. The product had 3.2-4.2% water by KF analysis. The product was analyzed by GC for residual IPA (acceptable - about less than or equal to about 5,000 ppm). The yield and purity were determined to be 100% and 99.69% (by HPLC), respectively.

[276] Therefore, Example 7 shows the recrystallization of Compound A from the HCl salt, Compound A-HCl, in accordance with the disclosure. EXAMPLE 8 Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)- [1,2,4]triazol[4,3-a]pyridin -3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (compound A) Scheme 8 Synthesis of (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3- a]pyridin -3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one

[277] (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-a]pyridin- 3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one was synthesized according to Scheme 8 by the following procedure. A clean, dry 60 L reactor was fitted with a reflux condenser, nitrogen inlet, and vented to a scrubber (Reactor 1). The jacket temperature of Reactor 1 was set at 20°C. A scrubber was fitted to the vent of Reactor 1, and aqueous bleach solution was charged to the scrubber. The circulating pump (commercial 5.25% NaOCl) was started. The purifier pump was turned on and N2 cleaning in Reactor 1 was started. Reactor 1 was charged with 1,599.5 g (0.52 equivalent) of Lawesson reagent. Reactor 1 was then charged with 24.4 L of acetonitrile (MeCN). Reactor 1 agitation has been started. 3,664.7 g (1.0 equivalent) of HYDZ were added to the reactor in portions over 1 ± 0.5 h, using acetonitrile (5 l) as a rinse. The reactor was heated to 50 ± 5°C and aged until an LC assay showed HYDZ consumption (>99% conversion).

[278] The reactor was cooled to 20°C and the reaction was analyzed by HPLC for Compound A. The assay showed a crude yield of 99% of Compound A.

[279] The contents from Reactor 1 were transferred to a second reactor, Reactor 2, through a 1 micron in-line filter. Reactor 2 was charged with 2 l of water. Reactor 2 was connected to a batch concentrator and vacuum distilled to a final volume of about 10 l. The jacket temperature was 50°C during distillation and the temperature was maintained below 50°C. The batch was then cooled to 20°C.

[280] In a separate container a 10% K2CO3 solution was prepared by adding 1,160 g of K2CO3 and 10,450 ml of water to the container and shaking the container until all the solid was dissolved. The K2CO3 solution was added to Reactor 2 through an in-line filter (5 μm). 13 kg of purified water was added to the reactor through the in-line filter (5 μm).

[281] A seed of Compound A was added to the reactor through an addition port. The resulting broth was aged for one hour during which crystallization was observed. The reactor was placed under vacuum and charged with 16 l of water. The resulting broth was aged at 20°C overnight. The product broth was filtered through a 25 μm filter cloth and washed with 10 l of a 10% solution of MeCN in water, followed by 12 l of water. The product was dried in a frit under a stream of air filtered by ambient humidity.

[282] Compound A was isolated as a crystalline solid monohydrate that reversibly dehydrates at <11% RH. After drying, there was 3.9% by weight of water present in constant weight solids as determined by KF. 3.317 kg, 89% yield, of Compound A was isolated as a pale yellow solid. The product had a purity of 99.4% by weight as determined by LCAP. EXAMPLE 9 Synthesis of NAPH - pathway 1 Scheme 9: Synthesis of NAPH - route 1

[283] NAPH starting material for the synthesis of Compound A was synthesized according to Scheme 9, route 1 by the following procedure. The jacket temperature of a 6 L jacket reactor, Reactor 1, was set at 22°C. 2,409 g (1.0 equivalent) of ethyl 5-bromo-2-methylnicotinate, 824 g (1.0 equivalent) of triazine, and 3.6 L of dimethyl sulfoxide (DMSO) were added to the reactor. The jacket temperature was set at 45°C. The reactor was stirred until a homogeneous solution resulted. Once complete dissolution had occurred (visually) the Reactor 1 jacket was cooled to 22°C.

[284] A second 60 ml reactor, Reactor 2, was prepared. 8.0 l of water was charged to a purifier. 4.0 l of 10 N sodium hydroxide was added to the scrubber and the scrubber was connected to Reactor 2. The cooling condenser was started. 6,411.2 g of cesium carbonate and 12.0 l of DMSO were added to Reactor 2. Stirring of Reactor 2 was started. The batch temperature of Reactor 2 was adjusted to 80°C. The solution from reactor 1 was added slowly for 1 h at 80°C, with internal temperature monitoring. 1.2 L of DMSO was added to Reactor 1 as a rinse. The DMSO rinse was transferred from Reactor 1 to Reactor 2 for 6 minutes. Reactor 2 was stirred for more than 1 h and the conversion to 3-bromo-1,6-naphthyridin-5(6H)-one was monitored by HPLC until there was < 1.0% ethyl 5-bromo-2-methylnicotinate remaining. . When the reaction was complete, the batch temperature was adjusted to 60°C. 24.0 l (10V) of water was added to Reactor 2 for 2 h, maintaining a reaction temperature of 60 ± 5°C, using a peristaltic pump at 192 ml/min. Reactor 2 was cooled to 22°C for 1 h 10 min. Stirring was continued at 22 ± 5°C until the supernatant was less than 3 mg/ml 3-bromo-1,6-naphthyridin-5(6H)-one (analyzed by HPLC). The crystallized product was filtered through an Aurora filter equipped with 25 μm polypropylene filter fabric. The reactor and filter cake were washed with a 75% by weight aq solution of H2O-DMSO (3 Vol made up of 1.6 L of DMSO and 5.6 L of water), followed by water (7.2 L, 3 Vol), and finally toluene (7.2 L, 3 Vol). The product cake was dried on the Aurora filter under vacuum with a stream of nitrogen at room temperature. The product was determined to be dry when KF was <2.0% by weight of water. 2,194 g of 3-bromo-1,6-naphthyridin-5(6H)-one was isolated as a beige solid. The chemical purity was 99.73%. The adjusted yield was 2,031.6 g (91.9%).

[285] The jacket temperature of a 100 l reactor, Reactor 3, was set at 15 ± 5°C. 6.45 l of 2-methoxyethanol was added to the reactor and stirring was started. (8,107 g) of lithium tert-butoxide was added in portions to the reactor, maintaining the reactor temperature in a range of 15 °C to 24 °C. 3,795 g of 3-bromo-1,6-naphthyridin-5(6H)-one was added to the reactor. 4 ml of 2-methoxyethanol was added to rinse the solids on the reactor wall. The reactor contents were stirred for at least 5 min. The reaction mixture was heated to distillation to remove i-BuOH and water, under 1 atm of nitrogen (jacket temperature 145°C). Distillation continued until the temperature of the pot reached 122 ± 3°C. The reactor contents were divided and analyzed for water content by KF. The reaction mixture was cooled to less than 35°C. 243 g of CuBr was added to the reactor. The reaction mixture was degassed by applying a vacuum at 50 torr (6.66 Kpa) and filling with nitrogen three times. The batch was heated to 120 ± 5°C keeping the jacket temperature below 150°C. The batch was stirred (174 RPM) for 15.5 h. The reaction sample was taken and the progress of the reaction was monitored by HPLC. When the remaining 3-bromo-1,6-naphthyridin-5(6H)-one was less than 1%, the jacket temperature was cooled to 25°C.

[286] An Aurora filter was equipped with a 25 μm PTFE fabric and loaded with Celite®. The reactor content was transferred to the filter fabric and the filtrate was collected in the reactor. 800 ml of 2-methoxyethanol was added to the reactor and stirred. The reactor contents were transferred to the filter and the filtrate was collected in the reactor. 5.6 l of acetic acid was added to the reactor to adjust the pH to 6.5, maintaining the temperature at less than 32°C. The batch was then heated to 80°C. The reaction mixture was concentrated to 3.0 ± 5 Vol (about 12 l) at 80 ± 5°C via vacuum distillation.

[287] In a separate container labeled HEDTA Solution, 589.9 g of N-(2-hydroxyethyl)ethylenediaminetriacetic acid trisodium hydrate salt and 7,660 ml of water were mixed to prepare a clear solution. The HEDTA solution was slowly added to the reactor maintaining the batch temperature at about 80-82°C. The batch was then cooled to 72 °C.

[288] An aqueous seed broth of NAPH (31.3 g) in 200 ml of water was added to the reactor. The broth was aged for 30 ± 10 min. 20 l of water was slowly added to the reactor to maintain the temperature at 65 ± 5°C. The batch was aged at 65 ± 5°C for 30 minutes. The batch was cooled to 20°C for 1 h. The reactor contents were purified with compressed air for 1 h, and then the batch was also cooled to -15 ° C and aged for 12.5 h. The batch was filtered through a centrifuge equipped with 25 μm PTFE filter cloth. 5.31 kg of wet cake was collected (60-62% by weight). The wet cake was dissolved in 6V HEDTA solution and filtered through the centrifuge. The collected wet cake was dried in the centrifuge, and transferred to an Aurora filter for continued drying.

[289] 2.82 kg (76% isolated yield) of NAPH was collected having a water content of 2.7% by KF.

[290] Therefore, Example 9 shows the synthesis of NAPH according to the examples. EXAMPLE 10 Synthesis of NAPH - pathway 2 Scheme 10: Synthesis of NAPH via pathway 2

[291] NAPH starting material for the synthesis of Compound A was synthesized according to Scheme 10, Route 2, by the following procedure.

[292] Preparation of protected 2-methoxy-pyridin-4-ylamine. A 1,600-L reactor was scrubbed with nitrogen and charged with 120 L of N,N-dimethylacetamide, 100.0 kg of 2-methoxy-pyridin-4-ylamine, and 89.6 kg of triethylamine, maintaining the reactor temperature below at 20°C. In a separate container, 103.0 kg of pivaloyl chloride were dissolved in 15.0 l of N,N-dimethylacetamide and cooled to less than 10 ° C. The pivaloyl chloride solution was added to the reactor using an addition funnel for 3.2 hours maintaining the reactor temperature between 5°C and 25°C. The addition funnel was washed with 15.0 l of N,N-dimethylacetamide, which was added to the reactor. The reaction was stirred for 2.3 hours at 20-25°C. A reaction sample was taken and analyzed for 2-methoxy-pyridin-4-ylamine by TLC. No 2-methoxy-pyridin-4-ylamine remained in solution and the reaction was aged at 20-25°C under nitrogen overnight. 1200 l of deionized water was added to the reaction for 2 hours while the reaction was maintained at 5-15°C. The resulting mixture was stirred at 15°C for 2 hours and then cooled to 5°C. The reaction was centrifuged at 700-900 rpm in 3 batches. Each batch was washed 3 times with deionized water (3x 167 l) at 800 rpm. The wet solids obtained were dried under vacuum at 55°C for 18 hours in 2 batches, sieved and dried again under vacuum at 55°C for 21 hours until the water content was <0.2% as determined by KF. 80.4 kg (89.7% yield) of the protected 2-methoxy-pyridin-4-ylamine was collected as a white solid.

[293] Preparation of protected 3-formyl-4-amino-2-methoxypyridine. A 1,600 l reactor was scrubbed with nitrogen and charged with 1,000 l of THF and 70.5 kg of the protected 2-methoxy-pyridin-4-ylamine. The reaction was stirred for 10 minutes at 15-25°C. The reaction was cooled to -5°C and 236.5 kg of n-hexyllithium (solution in hexane) were added for 11.5 hours maintaining the reaction temperature at <-4°C. The reaction was maintained at <-4°C for 2 hours. The reaction sample was quenched with D2O and the extent of ortho-lithiation was determined by 1H MRI (98.2% conversion). 61.9 kg of dimethylformamide (DMF) was added at <-4°C for 3.2 h. After stirring for 7.5 hours at <-4°C, a sample of the reaction was analyzed for conversion by HPLC (98.5% conversion).

[294] A 1,600 l reactor, Reactor 2, was scrubbed with nitrogen and charged with 145 l of THF and 203.4 kg of acetic acid. The resulting solution was cooled to -5°C. The content from the first reactor was transferred to Reactor 2 for 2.5 hours at 0°C. The first reactor was washed with 50 l of THF and the wash was transferred to Reactor 2. 353 l of deionized water was added to Reactor 2 keeping the temperature below 5°C. After 15 minutes of decantation, the aqueous layer was removed and the organic layer was concentrated at atmospheric pressure for 5 hours until the volume was 337 l. Isopropanol (350 l + 355 l) was added and the reaction was concentrated again at atmospheric pressure until the volume was 337 l. The distillation was stopped and 90 l of isopropanol was added to the reactor at 75-94°C. 350 l of deionized water was added to the reactor at 60-80°C for 1 h (the temperature was about 6065°C at the end of the addition). The reaction was cooled to 0-5°C. after 1 hour, the resulting suspension was filtered. Reactor 2 was washed twice with deionized water (2 x 140 l). Washes were used to rinse the solid in the filter. The wet solid was dried under vacuum at 50°C for 15 h. 71.0 kg (80% yield) of the protected 3-formyl-4-amino-2-methoxypyridine were produced. The purity of the substituted formyl pyridine was 92.7% by LCAP.

[295] A 1,600 l reactor, Reactor 3, was scrubbed with nitrogen and successively charged with 190 l of ethanol, 128.7 kg of protected 3-formyl-4-amino-2-methoxypyridine, 144 l of deionized water and 278 .2 kg of sodium hydroxide. The batch was heated to 60-65°C and 329.8 kg of the bisulfite adduct was added for 1 h. After 1 hour of shaking, the sample was removed for HPLC analysis which showed 100% conversion. The batch was aged 2 hours at 60-65°C, and then slowly cooled to 20-25°C. The batch was aged 12 h at 2025°C. The batch was filtered and the reactor was washed with water (2x 125 l). The washes were used to rinse the solid in the filter. The wet solid was transferred to the reactor with 500 l of deionized water and heated at 45-50°C for 1 h. The batch was brought back to 20-25°C (24 h). The solid was filtered and the reactor was washed with deionized water (2x 250 l). washes were used to rinse the solid in the filter. 112.5 kg of white wet solid was obtained (containing 85.1 kg (dry) of naphthyridine, 72.3% yield, greater than 97% purity as determined by HPLC). The wet product was used directly in the next step, without drying.

[296] A 1,600 l reactor was scrubbed with nitrogen and charged with 417 l of deionized water and 112.5 kg of wet naphthyridine. The purifier was filled with 700 l of water and 92.2 kg of monoethanolamine. A hydrochloric acid solution (46.6 kg diluted in 34 l of deionized water) was added to the reactor at 15-20°C for 10 minutes. The batch was heated at 60-65°C for 3 h. A sample of the batch was taken and had no starting material remaining as determined by TLC. A concentrated sodium hydroxide solution (58.2 kg in 31 l of deionized water) was added to the reactor at 60-65°C. 65% of the solution was added for 15 minutes and then the batch was seeded with crystallized NAPH. Crystallization was observed after 2.5 h and then the remaining 35% sodium hydroxide solution was added (pH - 11.1). The batch was cooled to 25-30°C and a solution of monobasic sodium phosphate (1.8 kg in 2.9 l of deionized water) was added for 25 minutes at 25-30°C) (pH = 6.75 ). The batch was stirred at 15-20°C for 12 hours and filtered. The reactor was washed twice with deionized water (2x 176 l). Washes were used to rinse the solid in the filter. The wet solid was dried under vacuum at 50°C until the water content was <5% (by KF), to generate 78.1 kg (73.8% yield, >95%)) of NAPH as a beige powder. .

[297] Thus, Example 10 shows the synthesis of NAPH in accordance with the disclosure. EXAMPLE 11 Synthesis of (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanoic acid naphthalene-2-sulfonate (NAPA) Scheme 11: Synthesis of NAPA, route 3

[298] NAPA was synthesized according to Scheme 11, route 3 by the following procedure. 4.75 g of 3-(2-Methoxyethoxy)-1,6-naphthyridin-5(6H)-one was suspended in 45 ml of DMF. 2.58 ml (s)-methyl lactate and 9.05 g of triphenylphosphine were added to the suspension. The reaction mixture was cooled to 0°C. 5.12 ml of diethyl azodicarboxylate (DEAD) was added in drops via syringe. The mixture was stirred at 0°C for 1 h. A sample of the reaction was taken and the reaction was determined to be complete by LCMS. The reaction mixture was concentrated under vacuum to generate crude material as a yellow oil.

[299] 1 g of the raw material was loaded into dichloromethane on a silica gel pre-column. The sample was purified using the “Isco Combi-Flash” system; 40 g column, hexane/ethyl acetate solvent system, gradient 0-100% ethyl acetate for 15 minutes. The product eluted in 100% ethyl acetate. The product fractions were combined and concentrated under vacuum. 256 mg of (R)-methyl 2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl)propanoate was collected as a pale yellow oil.

[300] The remaining residue was partitioned between benzene and 6N aqueous hydrochloric acid (35.9 ml). The acid layer was extracted with benzene (3x), diethyl ether (2x), ethyl acetate (2x) and dichloromethane (1x). The dichloromethane layer was extracted again with 6N aqueous hydrochloric acid (2x). The aqueous layer was diluted with THF (80 ml). The mixture was heated at 80°C for 3 h. The reaction mixture was concentrated to remove THF. The remaining acidic aqueous layer was extracted with ethyl acetate and dichloromethane. The aqueous layer was concentrated under vacuum. The remaining solid was triturated with methanol. The mixture was filtered to remove the solid (naphthyridone). The methanol layer was concentrated under vacuum. The remaining solid was dried overnight in a freeze dryer. 10.2 g of material was collected as a yellow solid. NAPA constituted 72% of the material as determined by HPLC.

[301] 1.0 g of the crude material was dissolved in hot minimum iPrOH then filtered and cooled to RT. No crystallization occurred; therefore, the solution was cooled in the freezer overnight. A yellow precipitate was formed. The solid was collected on a glass tray and washed with minimal iPrOH. 171 mg of yellow solid was collected, which was NAPA with a small amount of naphthyridone by LC-MS and 1H MRI.

[302] Acid-base extraction. About 1 g of the crude material was dissolved in saturated aqueous sodium bicarbonate. The crude material was extracted with dichloromethane. The pH of the aqueous layer was adjusted to 6-7 with acetic acid then extracted with dichloromethane. 11 mg of the product was isolated; most of the product remained in the aqueous layer. The pH was reduced to approximately 4-5 with more acetic acid. The aqueous layer was extracted with dichloromethane, ethyl acetate, and 15% methanol/dichloromethane. The organic layers were concentrated in vacuo to yield 260 mg of NAPA as a free base, as determined by LC-MS.

[303] Therefore, Example 11 shows the synthesis of NAPA in accordance with the disclosure. EXAMPLE 12 Synthesis of bisulfite adduct Scheme 12: Bisulfite adduct synthesis Method 1

[304] The bisulfite adduct was synthesized according to Method 1 of Scheme 12 by the following procedure. A 2 L round bottom flask (RBF) was purified with nitrogen and charged with 73.1 ml of reagent grade oxalyl chloride and 693 ml of methylene chloride. The batch was cooled to less than -40°C. 88 ml of dimethyl sulfoxide was added to the flask via an addition funnel at -40°C. After addition, the batch was stirred for 10 minutes at -60°C. 97 ml of diethylene glycol monomethyl ether was added to the lower flask at -50°C for 10 minutes. The resulting white broth was stirred at -60°C for 30 minutes. 229 ml of triethylamine was added to the flask via a lower addition funnel at -30°C for 1 h. The batch was heated to RT. 300 ml of MTBE was added to the flask and the batch was stirred for 15 min. The broth was filtered through a funnel and the cake was washed with 300 ml of MTBE. The filtrate was concentrated to 350-400 g and then filtered again to remove triethylamine-HCl salt, and the solid was rinsed with MTBE, resulting in 357.7 g of a slightly yellow filtered solution. The solution was analyzed by QNMR and comprised 19% by weight (68 g) of the desired aldehyde (70% crude yield). The solution was concentrated to 150.2 g.

[305] A 500 ml RBF was charged with 60.0 g of sodium bisulfite and 150 ml of water to generate a clear solution. The concentrated aldehyde solution was added to the aqueous bisulfite solution for 5 minutes. An exothermic temperature rise was observed up to 60°C from 18°C. The solution was rinsed with 15 ml of water. The resulting yellow solution was cooled to RT and stirred under a nitrogen wash overnight. One QNMR of the solution was removed. The solution contained 43% by weight of the bisulfite adduct (300 g, 70% yield).Method 2

[306] The bisulfite adduct was synthesized according to Method 2 of Scheme 12 by the following procedure. A 2,500 L reactor was scrubbed with nitrogen and charged with 657.5 L of 2-methoxyethanol. 62.6 kg of lithium hydroxide monohydrate were added to the reactor keeping the temperature below 30°C. The reactor was heated to 113 ± 7°C. 270 l of solvent was distilled for 1 h and then the reactor temperature was adjusted to 110 °C. 269.4 kg of diethyl acetal bromoacetaldehyde were added for 16 minutes, maintaining the temperature between 110 and 120°C. The reaction was heated at reflux (115-127°C) for 13 hours. A sample of the reaction was analyzed and the conversion to 2-(2-methoxyethoxy)acetaldehyde was 98.3%. The reaction was cooled to 15-20°C and 1,305 l of methyl tert-butyl ether (MTBE) and 132 l of deionized water were added to the reactor. The reaction was stirred for 20 minutes and then decanted. The aqueous layer was transferred to a 1,600 l reactor and the organic layer was maintained in the first reactor. The aqueous layer was extracted with 260 l of MTBE for 10 minutes. After 10 minutes of decantation, the aqueous layer was removed and the organic layer was transferred to the first reactor. The mixed organic layers were washed twice, 15 minutes each, with a mixture of concentrated sodium hydroxide solution (2x 17.3 kg) diluted in deionized water (2x 120 l). The aqueous layers were removed, and the organic layer was concentrated at atmospheric pressure at 60-65°C until the volume was 540 l. The organic layer was cooled to 15-20°C to generate 2-(2-methoxyethoxy)acetaldehyde as an orange liquid solution (417.4 kg) containing 215.2 kg of pure product (87.3% yield) as determined. by 1H MRI and HPLC assay.

[307] A 1,600 l reactor, Reactor 3, was scrubbed with nitrogen and charged with 595 l of deionized water followed by 37.8 kg of sulfuric acid for 25 minutes via addition funnel, maintaining the temperature below 25 ° C. The addition funnel was washed with 124 l of deionized water and the wash was added to Reactor 3.

[308] A 2,500 l reactor, Reactor 4, was scrubbed with nitrogen and charged with 417.4 kg of 2-(2-methoxyethoxy)acetaldehyde solution. The contents of Reactor 3 were transferred to Reactor 4 for 25 minutes keeping the temperature of Reactor 4 below 35°C. The batch was aged at 30-35°C for 3 hours. A sample from the batch was taken and analyzed for 2-(2-methoxyethoxy)acetaldehyde. No 2-(2-methoxyethoxy)acetaldehyde remained. The batch was aged 5 h then cooled to 15-20°C.

[309] A solution of sodium carbonate (39.2 kg) in deionized water (196 l) was prepared in Reactor 3. The sodium carbonate solution was transferred to Reactor 4 for 25 minutes maintaining the temperature of Reactor 4 below of 30°C. The pH of the resulting mixture was pH 5-6. 1.0 kg of sodium carbonate was added per portion until the pH was about 7-8. A solution of sodium bisulfite (116.5 kg) in deionized water (218 L) was prepared in Reactor 3. The sodium bisulfite solution was transferred to Reactor 4 for 20 minutes keeping the temperature of Reactor 4 below 30° W. Reactor 3 was washed with deionized water (15 l) and the wash was added to Reactor 4. The batch was stirred for 1.2 hours. 23.3 kg of sodium bisulfite were added to Reactor 4 and the batch was aged overnight. The batch was concentrated under vacuum at 3050°C for 6.5 hours until precipitation was observed. The batch was cooled to 0-10°C at atmospheric pressure. After 30 minutes at 0-10°C, the suspension was filtered through 2 filters. Reactor 4 was washed with deionized water (2 x 23 l). the first wash was used to rinse the solid in the first filter and the second wash was used to rinse the solid in the second filter. The filtrates were combined to generate 473.9 kg of an aqueous solution of the bisulfite adduct (202.5 kg of pure product, 76.3% yield) as a yellow liquid.

[310] Therefore, Example 12 shows the synthesis of the bisulfite adduct according to the invention. EXAMPLE 13 Synthesis of 2,3-difluoro-5-(1-methyl-1h-pyrazol-4-yl)pyridine Scheme 13: Synthesis of 2,3-difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine, precursor for PIRH

[311] 2,3-Difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine was synthesized according to Scheme 13 by the following procedure. A boronic-boronate complex broth was prepared in a first 2-liter 3-neck round-bottom flask (RBF #1). RBF #1 was loaded with 141 g (66.4% by weight, 0.9 equivalents based on boronic ester) lithium 2-hydroxy-4,4,5,5-tetramethyl-2-(1-methyl- 1H- pyrazol-4-yl)-1,3,2-dioxaborolan-2-ide. 120 ml (1.6 Vol relative to 5-chloro-2,3-difluoropyridine) of 2-BuOH sparged with nitrogen (2 h) and 120 ml (1.6 Vol) of water sparged with nitrogen (2 h) were added to the RBF #1. Stirring and N2 cleanup were initiated.The reaction was aged at 20°C for at least 30 minutes (reactions aged at 24 h were also successful).

[312] A 2-liter 3-neck flask (RBF #2) was charged with 1.48 g (0.004 equivalents) of Xphospaladacyclo and 450 ml (6 Vol relative to 5-chloro-2,3-difluoropyridine) of 2-BuOH sprayed with nitrogen (2 h). Vacuum/N2 was cyclized into RBF #2 three times to inert the RBF with N2. The batch in RBF #2 was heated to 80°C. 75 g (1.0 equivalent) of 5-chloro-2,3-difluoropyridine was added to RBF #2.

[313] The boronic-boronate complex broth was transferred from RBF #1 to a 500 ml dropping funnel. RBF #1 was rinsed with 30 ml (0.4 Vol) of 2-BuOH. Using the dripping funnel, the boronic-boronate complex broth was added for 1 h to the hot solution mixture in RBF #2. After 1 h, 95% conversion was observed. If more than 90% conversion was not observed, more boronic-boronate complex broth was added (0.1 equivalent at a time with 1.6 Vol of 1:1 2-BuOH/water relative to the boronic-boronate complex). ). After the conversion was complete, the batch was cooled to 50°C. During cooling, 600 ml (8 Vol) of toluene was added to RBF #2. 300 ml (4 Vol) of 20% w/v NaHSO3 in water was added to RBF #2 and the batch was stirred at 50°C for at least 1 h. The batch was filtered using a 5 micron Whatman filter at 50°C in a 2 l Atlas reactor. RBF #2 was rinsed with 30 ml (4.0 Vol) of a 1:1 2-BuOH:toluene solution. The batch temperature was adjusted to 50°C in the Atlas reactor with stirring. Agitation was stopped and the phases were left to rest for at least 15 minutes, keeping the batch at 50°C. The bottom, aqueous layer was separated from the batch. The Atlas reactor was charged with 300 ml (4 Vol) of a 20% w/v NaHSO3 solution and the batch was stirred at 50°C for 1 h. Agitation was stopped and the phases were allowed to rest for at least 15 minutes at 50°C. The bottom, aqueous layer was removed. Stirring was started and the Atlas reactor was charged with 200 ml (4 Vol) of 0.5 M KF keeping the batch at 50°C for at least 30 minutes. Agitation was stopped and the phases were allowed to rest for at least 15 minutes at 50°C. The bottom, aqueous layer was removed. Stirring was started and the reactor was charged with 300 ml (4 Vol) of water. The batch was aged at 50°C for at least 30 minutes. Agitation was stopped and the phases were allowed to rest for at least 15 minutes at 50°C. The aqueous background was subsequently removed.

[314] The organic phase was concentrated by distillation under reduced pressure (180 torr (23.99 kPa), jacket temperature 70°C, internal temp. about 50°C) at a minimum stirring volume (about 225 ml). 525 ml (7 Vol) of 2-BuOH was added to the Atlas reactor. The organic batch was again concentrated using reduced pressure (85-95 torr (11.33-12.66 kPa), jacket temp. 75°C, internal temp. about 55°C) to a volume of minimum stirring (about 125 ml). The total batch volume was adjusted to 250 ml with 2-BuOH.

[315] 525 ml (7 Vol) heptane was added to the broth mixture in the Atlas reactor. The jacket temperature was adjusted to 100°C and the batch was aged for more than 15 min until the batch became homogeneous. The batch was cooled to 20°C for at least 3 h. A sample of the mixture was taken and the supernatant analyzed for 2,3-difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine. If the concentration was greater than 10 mg/ml, aging was continued for at least 1 h until the supernatant concentration was less than 10 mg/ml. The batch was filtered using a medium frit. The filter cake was washed with 150 ml (2 Vol) 2-BuOH/30% heptane solution, followed by 150 ml (2 Vol) heptane. The filter cake was dried under N2/vacuum. 76.64 g of 2,3-difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine was isolated as a white solid (87% yield).

[316] A 60 l jacketed reactor was equipped with a reflux condenser. Condenser cooling was started at 0 ± 5°C. The reactor was charged with 2,612 g (1 equivalent) of 2,3-difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine and placed under a nitrogen atmosphere. 31.7 L (12.2 Vol) of water was added to the reactor and the resulting broth was scrubbed with nitrogen for 1 h with stirring. 7,221 ml (6 equivalents) of hydrazine (35% by weight in water) were added to the reactor under a nitrogen atmosphere. The reactor was heated to 100°C for 2 ± 2 h until the reaction was complete by HPLC analysis. The reactor was cooled to 20°C over 2 ± 1 h at a rate of 40°C/h. The reactor contents were stirred for 10 ± 9 hours until the desired supernatant assay (< 2 mg/ml PIRH in mother liquor). Reactor contents were filtered through an Aurora filter equipped with 25 μm polypropylene filter fabric. The collected filter cake was washed with 12.0 l (4.6 V) of water in three portions. The filter cake was dried on the Aurora filter for 4-24 h at 22 ± 5°C, or until the product contained less than 0.5% water as determined by KF. The dried product was collected. 2.69 kg (97% yield) of 2,3-Difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine was collected as a white crystalline solid. The solid had a water content of 12 ppm as determined by KF.

[317] Thus, Example 13 shows the synthesis of 2,3-Difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine, a precursor for PIRH, according to the disclosure. EXAMPLE 14 PIRH SYNTHESIS - PATHWAY 2 Scheme 14: Synthesis of 3-fluoro-2-hydrazinyl-5-(1-methyl-1H-pyrazol-4-yl)-pyridine (PIRH)

[318] 3-fluoro-2-hydrazinyl-5-(1-methyl-1H-pyrazol-4-yl)-pyridine was synthesized according to Scheme 14 by the following procedure. A 60-L jacketed reactor was equipped with a 5-L addition funnel and the jacket temperature was adjusted to 20 ± 5°C. 36.0 L (15 Vol) of 2-methyltetrahydrofuran was added to the reactor through a 20 μm in-line vacuum filter using polypropylene transfer lines. The solution was sprayed by bubbling nitrogen through a rod into the solution for 1 ± 0.5 h with stirring. After 1 h, the dipstick was removed but a nitrogen flush continued. 1.55 kg of sprayed 2-MeTHF was removed to be used as rinse volumes. 36.7 g of Pd2dba3, 75.6 g of X-Phos, 259 g of tetrabutylammonium bromide and 7,397 g of tribasic potassium phosphate were added to the reactor. The opening was rinsed with 0.125 kg of sprayed 2-MeTHF. The reactor was stirred and nitrogen flushing continued for 1 ± 0.5 h. Next, the nitrogen wash was stopped and the reaction was left under positive nitrogen pressure.

[319] 3.6 l (1.5 Vol) of spray water was prepared in advance by bubbling nitrogen through a 4 l water bottle for 1 ± 0.5 h. The nitrogen sparged water was transferred to the 5 L addition funnel through a 20 μm in-line vacuum filter using polypropylene transfer lines, and then slowly added to the reaction while maintaining the internal temperature at 20 ± 5°C. The 5 L addition funnel was replaced with a 2 L addition funnel. 2,412 g of 5-chloro-2,3-difluoropyridine were added to the 2 l addition funnel. 5-Chloro-2,3-difluoropyridine was then added to the reaction via the 2 L addition funnel. The 2-L addition funnel was rinsed with 0.060 kg of sprayed 2-MeTHF. 83.8 g (1.15 equivalent) of 1-methylpyrazole-4-boronic acid, pinacol ester was added to the reactor, the reactor was flushed with nitrogen for 1 ± 0.5 h, and then left under a positive nitrogen pressure . The internal temperature of the reactor was adjusted to 70 ± 5°C. The batch was stirred at 70 ± 5°C for at least 4 hours after the final reagent was added. A sample was taken from the reaction and the progress of the reaction analyzed for conversion. Reaction progress was checked every 2 hours until the reaction was complete (e.g., greater than 99% conversion). The batch was cooled to 20 ± 5°C.

[320] A 20% w/v solution of sodium bisulfite (12.0 l, 5 Vol) was prepared by loading 12.0 l of water, and then 2,411 g of sodium bisulfite into a suitable container and stirring. until homogeneous. The 20% sodium bisulfite solution was transferred into the reactor and stirred for 30 minutes. Stirring was stopped, the phases were allowed to stand, and the aqueous phase was removed. A 0.5 M potassium fluoride solution (12.0 l, 5 Vol) was prepared by loading 12.0 l of water and 348 g of potassium fluoride into a suitable container and stirring until homogeneous. The 0.5 M potassium fluoride solution was transferred to a reactor and stirred for 30 minutes. Stirring was stopped, the phases were allowed to stand, and the aqueous phase was removed. A 25% w/v solution of sodium chloride (12.0 l, 5 Vol) was prepared by charging a suitable container with 12.0 l of water and 2999 g of sodium chloride and stirring until homogeneous. The 25% sodium chloride solution was transferred to the reactor and stirred for 30 minutes. Stirring was stopped, the phases were allowed to stand, and the aqueous phase was removed from the reactor.

[321] The organic phase was distilled at a constant volume (36 l, 15 Vol), while maintaining the internal temperature of the reactor at 50 ± 5°C by adjusting the vacuum pressure until a maximum of 0.3% water remained . 2- Methyltetrahydrofuran was added to the reactor as necessary to maintain constant volume. The batch was cooled to 20°C and transferred to drums. The batch was transferred using a polishing filter (using a 5 μm in-line filter) into a 60 L jacketed reactor with an attached batch concentrator. 1.2 L of 2-MeTHF was used to rinse the drums. The batch was concentrated to about 9 Vol while maintaining the internal temperature of the flask at 50 ± 5°C by adjusting the vacuum pressure. The batch was then distilled at constant volume (22.0 l, 9 Vol), while maintaining the internal temperature of the flask at 50 ± 5°C by adjusting the vacuum pressure. Heptane was added with residual vacuum until a supernatant mixture of 2-MeTHF:15% heptane was obtained. The pressure brought to atmospheric pressure under nitrogen. The reactor was cooled to 20 ± 5°C over 2 ± 2 h. The batch was stirred at 20 ± 5°C until an assay of the supernatant indicated that the amount of product was 7 mg/ml 2,3-difluoro-5-(1-methyl-1H-pyrazol-4-yl) pyridine.

[322] A 10% 2-MeTHF:heptane wash solution (7.2 l, 3 Vol) was prepared by mixing 720 ml of 2-MeTHF and 6.5 l of heptane. The batch broth was filtered through an Aurora filter equipped with a 25 μm polypropylene filter cloth, resulting in heavy crystals that required pumping with a diaphragm pump using polypropylene transfer lines to the top of the reactor during stirring. The mother liquor was recycled to complete the transfer. The reactor and filter cake were washed with two portions of 2-MeTHF:10% heptane wash solution (3.6 l each). The product cake was dried in a frit under a stream of nitrogen at room temperature. 2,3-Difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine was determined to be dry when the 1H-NMR assay was < 0.05 ± 0.05. 2.635 kg were isolated as an off-white crystalline solid (85% yield).

[323] A 60 l jacketed reactor was equipped with a reflux condenser. Condenser cooling was started at 0 ± 5°C. The reactor was charged with 2,612 g (1 equivalent) of 2,3-difluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridine and placed under a nitrogen atmosphere. 31.7 L (12.2 Vol) of water was added to the reactor and the resulting broth was scrubbed with nitrogen for 1 h with stirring. 7,221 ml (6 equivalents) of hydrazine (35% by weight in water) were added to the reactor under a nitrogen atmosphere. The reactor was heated to 100°C for 2 ± 2 h until the reaction was complete by HPLC analysis. The reactor was cooled to 20°C over 2 ± 1 h at a rate of 40°C/h. The reactor contents were stirred for 10 ± 9 hours until the desired supernatant assay was achieved (< 2 mg/ml PIRH in mother liquor). Reactor contents were filtered through an Aurora filter equipped with 25 μm polypropylene filter fabric. The collected filter cake was washed with 12.0 l (4.6 V) of water in three portions. The filter cake was dried on the Aurora filter for 4-24 h at 22 ± 5°C, or until the product contained less than 0.5% water as determined by KF. The dried product was collected. 2.69 kg was isolated as a white crystalline solid (97% yield). The water content was determined to be 12 ppm per KF.

[324] Thus, Example 14 shows the synthesis of PIRH in accordance with the disclosure.

[325] Particular aspects and modalities are described in the following paragraphs.

[326] In one aspect, the present disclosure provides a method comprising the reaction of (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl )-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl)propanehydrazide (“HYDZ”): under conditions sufficient to form (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazol[4,3- a] pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“A”):

[327] In one aspect, the reaction comprises contacting HYDZ with a thiophosphetan compound. The thiophosphetan compound may be a 2,4-bis(aryl)-1,3-dithia-2,4-diphosphetan 2,4-disulfide compound. In a further aspect, the 2,4-bis(aryl)-1,3-dithia-2,4-diphosphetan 2,4-disulfide compound is:

[328] In another aspect, the 2,4-bis(aryl)-1,3-dithia-2,4-diphosphetan 2,4-disulfide compound is:

[329] The present disclosure further allows that the thiophosphethane compound may be present in an amount of at least about 0.4 equivalent, or at least about 0.45 equivalent, or at least about 0.5 equivalent; or in a range of about 0.4 equivalent to about 0.65 equivalent, or about 0.45 equivalent to about 0.65 equivalent, or about 0.5 equivalent to about 0.55 equivalent, or about 0.52 equivalent.

[330] In one aspect, the contact occurs at a temperature in a range of 35°C to 70°C, or 40°C to 60°C, or 45°C to 55°C. In another aspect, contact occurs by a process comprising adding HYDZ to a broth comprising the thiophosphetan compound. In a further aspect, HYDZ is added to the broth in portions. In another aspect, the broth comprises acetonitrile. In yet another further aspect, the method may further comprise contacting Compound A with an acid under conditions sufficient to form a salt of compound A. The acid may be selected from the group consisting of hydrochloric acid, phosphoric acid, camphorsulfonic acid, 2-naphthylsulfonic acid, methanesulfonic acid, benzenesulfonic acid and derivatives thereof, succinic acid, tartaric acid, fumaric acid, maleic acid, and combinations thereof. In one aspect, the acid comprises hydrochloric acid. The present disclosure allows the yield of the Compound A salt to be at least about 80%, or at least about 90%, or at least about 95%, or at least about 99%. The purity of the Compound A salt may be at least about 99%, or at least about 99.5%, or at least about 99.7%. Furthermore, the optical purity of the Compound A salt may be at least about 98%, or at least about 99%, or at least about 99.5%, or at least about 99.9% ee.

[331] In another aspect, the methods of the present disclosure may further comprise contacting Compound A with a water-rich solvent having a pH of at least 7 under conditions sufficient to form a monohydrate form of compound A. In one aspect , the solvent comprises water and acetonitrile, and wherein water may be present in an amount of at least 80% by weight. It is contemplated that a monohydrate form of compound A has a purity of at least about 99.5%, or at least about 99.7%, or at least about 99.9%, or about 100%. In one aspect, a monohydrate form of compound A has an optical purity of at least about 99.9% or about 100%.

[332] The present disclosure further provides a method, wherein the reaction comprises contacting HYDZ with a phosphorus (V) dehydrating agent. In one aspect, the dehydrating agent comprises a compound having a structure: wherein each L is independently C1-6 alkyl, O-C1-6 alkyl, aryl, O-aryl, Br, Cl, or I; and R1 is Cl, Br or I. In a further aspect, each L can be selected from the group consisting of Me, Et, Pr, iPr, n-Bu, s-Bu, i-Bu, t-Bu, O- Me, O-Et, O-Pr, O-iPr, On-Bu, Os-Bu, Oi-Bu, Ot-Bu, phenyl, O-phenyl, Br and Cl. In yet another further aspect, each L is selected from the group consisting of Me, Et, t-Bu, O-Me, O-Et, Hi-Bu, phenyl, O-phenyl, Br and Cl. In one aspect, R1 may be Cl or Br. It is contemplated that the dehydrating agent may comprise diphenylphosphinyl chloride, POCl3, or a combination thereof. In one aspect, the dehydrating agent is present in an amount of about 1.8 equivalents to about 3 equivalents. In a further aspect, the dehydrating agent is present in an amount of about 2.3 to about 2.5 equivalents. In one aspect of the present disclosure, contact occurs in the presence of a base. In a further aspect, the base is a pyridine. In one aspect, the base comprises 2,4-lutidine, 2,4,6-colidine, and a combination thereof. In one aspect of the present disclosure, the base is present in an amount of at least about 0.2 equivalents greater than the amount of the dehydrating agent. In another aspect, the base is present in an amount of about 2.5 to about 4.0 equivalents. In a further aspect, the base is present in an amount of about 2.5 to about 3.5 equivalents.

[333] The present disclosure further provides a method, in which contact occurs in an amide, sulfolane or nitrile solvent. In one aspect, the solvent comprises N-methyl-2-pyrrolidone ("NMP"), dimethylacetamide ("DMAc"), acetonitrile, propionitrile, and combinations thereof. In one aspect, the contact occurs at a temperature in a range of 60°C to 90°C. In another aspect, the temperature is in a range of 83°C to 86°C. The methods of the present disclosure may further comprise contacting Compound A with an acid under conditions sufficient to form a salt of compound A. The acid may be selected from the group consisting of hydrochloric acid, phosphoric acid, camphorsulfonic acid, 2-naphthylsulfonic acid , methanesulfonic acid, benzenesulfonic acid and derivatives thereof, succinic acid, tartaric acid, fumaric acid, maleic acid, and combinations thereof. In one aspect, the acid comprises hydrochloric acid. In the method described above, the yield of the Compound A salt may be at least about 85%, or at least about 90%, or at least about 95%, or at least about 99%. The purity of the Compound A salt is at least about 88%, or at least about 90%, or at least about 95%. The optical purity of the Compound A salt is at least about 99%, or at least about 99.5%, or at least about 99.8%, or at least about 99.9% ee.

[334] The present disclosure further provides a method, in which the reaction comprises contacting HYDZ with a phosphine: wherein each L' is independently an alkyl, aryl or heteroaryl group; and an oxidant. In one aspect, each L' is a C1-6 alkyl group. In another aspect, each L' is a C1-4 alkyl group. In a further aspect, each L' is selected from the group consisting of Me, Et, Pr, iPr, n-Bu, s-Bu, i-Bu, and t-Bu. In one aspect, phosphine is trimethyl phosphine. In one aspect, each L' is an aryl group or a heteroaryl group. In another aspect, each L' is phenyl or pyridine. In a further aspect, the phosphine is triphenyl phosphine or diphenyl-2-pyridylphosphine. In one aspect, phosphine is present in an amount in a range of about 1 equivalent to about 2 equivalents. In another aspect, the phosphine is present in an amount of about 1.1 equivalent, or about 1.2 equivalent, or about 1.3 equivalent, or about 1.4 equivalent, or about 1.5 equivalent. , or about 1.6 equivalents, or about 1.7 equivalents, or about 1.8 equivalents, or about 1.9 equivalents. In one aspect, the oxidant is selected from the group consisting of benzoquinone, azodicarboxylate, aryl and/or heteroaryl disulfide, aryl and/or heteroaryl hypochloride, and combinations thereof. In a further aspect, the benzoquinone comprises 2,3-dichloro-5,6-dicyanobenzoquinone (“DDQ”). In a further aspect, the azodicarboxylate comprises diethyl azodicarboxylate ("DEAD"), diisopropyl azodicarboxylate ("DIAD") or di-(4-chlorobenzyl)azodicarboxylate. In a further aspect, the aryl and heteroaryl disulfide comprise benzothiazyl disulfide. In one aspect, the oxidant is present in an amount in a range of about 1 equivalent to about 2 equivalents. In another aspect, the oxidant is present in an amount of about 1.1 equivalent, or about 1.2 equivalent, or about 1.3 equivalent, or about 1.4 equivalent, or about 1.5 equivalent. , or about 1.6 equivalent, or about 1.7 equivalent, or about 1.8 equivalent, or about 1.9 equivalent. In one aspect, the dehydrant also comprises an azide. In a further aspect, the azide is trimethylsilyl azide (“TMS azide”). In one aspect, the contact occurs at a temperature in a range of 15°C to 35°C, or 20°C to 30°C, or 30°C to 70°C, or 40°C to 60°C. In one aspect, the contact occurs in a solvent selected from a chlorinated solvent, an ether solvent, acetonitrile, and combinations thereof. In a further aspect, the ether solvent comprises tetrahydrofuran, diethyl ether, or a combination thereof. In one aspect, the reaction further comprises contacting Compound A with an acid under conditions sufficient to form a salt of compound A. In a further aspect, the acid is selected from the group consisting of hydrochloric acid, phosphoric acid, camphorsulfonic acid, 2-naphthylsulfonic acid, methanesulfonic acid, benzenesulfonic acid and derivatives thereof, succinic acid, tartaric acid, fumaric acid, maleic acid, and combinations thereof. In a further aspect, the acid comprises hydrochloric acid.

[335] The present disclosure also comprises the crystallization of Compound A in a solution comprising alcohol and water, under conditions sufficient to form a monohydrate form of Compound A:

[336] Alcohol includes methanol, ethanol, isopropanol, or combinations thereof. In one aspect, the alcohol comprises ethanol. In another aspect, the alcohol comprises isopropanol. The ratio of alcohol to water can be in a range of about 1:10 to about 10:1, or about 1:1, or about 1:2, or about 1:3, or about 1: 4, or about 1:5, or about 1:6, or about 1:9, or about 1:8, or about 1:9, or about 1:10, or about 10:1 , or about 9:1, or about 8:1, or about 7:1, or about 6:1, or about 5:1, or about 4:1, or about 3:1, or about 2:1. In one aspect, the ratio of alcohol to water is about 1:3, or about 1:4, or about 1:5, or about 1:6, or about 2:1. In a further aspect of the present disclosure, the yield of a monohydrate form of compound A is at least about 95%, or at least about 97%, or at least about 99%. The purity of a monohydrate form of compound A may be at least about 99%, or at least about 99.5%, or at least about 99.7%, or at least about 99.9%. The optical purity of a monohydrate form of compound A may be at least about 99.5%, or at least about 99.7%, or about 100% ee.

[337] The methods of the present disclosure allow HYDZ to be formed by reaction of (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)-yl acid )propanoic (“NAPA”): with 3-fluoro-2-hydrazinyl-5-(1-methyl-7H-pyrazol-4-yl)pyridine (“PIRH”): and a binding reagent, and under conditions sufficient to form HYDZ:

[338] In one aspect, NAPA may be a zwitterion. In another aspect, NAPA may be a salt. The salt contemplated herein comprises HCl, HBr, a sulfonic acid, or diisopropylamine, or potassium cation. In one aspect, the salt comprises HCl. In a further aspect, the sulfonic acid salt may be selected from the group consisting of 2-naphthalene sulfonic acid, 1-naphthalene sulfonic acid, m-xylenesulfonic acid, p-toluene sulfonic acid, benzenesulfonic acid, 2-nitrobenzenesulfonic acid, 2,5-dichlorobenzenesulfonic acid, (-)-10-camphorsulfonic acid, (+)-camphor-10-sulfonic acid, p-chlorobenzenesulfonic acid, methanesulfonic acid, and combinations thereof. In yet another further aspect, the salt comprises 2-naphthalene sulfonic acid.

[339] The present disclosure allows that the binding reagent may include a reagent selected from the group consisting of a carbodiimide reagent, a phosphonium reagent, a uronium reagent, an imonium reagent, an imidazolium reagent, a organophosphorus, an acid chloride reagent, a chloroformate reagent, a pyridinium reagent, and combinations thereof. In one aspect, the carbodiimide reagent may be selected from the group consisting of N,N'dicyclohexylcarbodimide ("DCC"), 1,3-diisopropylcarbodiimide ("DIC"), l-ethyl-3-(3-dimethylaminopropyl)carbodiimide (“EDC”), isopropylcarbodimide (“CIC”), and combinations thereof. In another aspect, the phosphonium reagent comprises (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate ("BOP") or benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate ("PyBOP"). In a further aspect, the uronium reagent comprises 1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazol[4,5-b]pyridinium 3-oxide hexafluorophosphate ("HATU") or O-( Benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (“HBTU”). In another aspect, the imidazolium reagent comprises 1,1'-carbonyldiimidazole ("CDI"). The acid chloride reagent may comprise pivaloyl chloride or 2,4,6-trimethylbenzoyl chloride. The chloroformate reagent comprises ethyl chloroformate or isobutyl chloroformate.

[340] In the method described above, the reaction can be carried out in the presence of a binding additive. In one aspect, the binding additive may be a benzotriazole, a dicarboximide, a succinimide, or a combination thereof. In one aspect, the binding additive may be selected from the group consisting of N-hydroxysuccinimide ("HOSu"), N-hydroxy-5-norbornene-2,3-dicarboximide ("HONB"), 1-hydroxybenzotriazole ("HOBt"). ”), 6-chloro-1-hydroxybenzotriazole (“Cl-HOBt”), 1-hydroxy-7-azabenzotriazole (“HOAt”), and combinations thereof. In a further aspect, the binding additive comprises HOBt.

[341] In one aspect, the reaction can occur in the presence of a base. In one aspect, the base comprises a tertiary amine. The tertiary amine may be selected from the group consisting of N,N-diisopropylethylamine ("DIEA"), triethylamine ("TEA"), N-methylmorpholino ("NMM"), Hünig's base, and combinations thereof. In one aspect, the base may be present in an amount of at least about 1 equivalent. In a further aspect, the reaction can occur in an aprotic solvent. The aprotic solvent may be selected from the group consisting of acetonitrile, dichloromethane, tetrahydrofuran, dimethylacetamide (“DMAc”), and combinations thereof. In one aspect, the aprotic solvent may be DMAc. The yield of HYDZ may be at least about 75%, or at least about 85%, or at least about 90%, or at least about 95%. The purity of HYDZ may be at least about 95%, or at least about 97%, or at least about 99%, or at least about 99.5%, or about 100%. The optical purity of HYDZ is at least about 99%, or at least about 99.5%, or at least about 99.7%, or at least about 99.9% ee.

[342] The present disclosure provides methods in which NAPA is formed by mixing 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“NAPH”): and a basis, under conditions sufficient to form NAPA: wherein R1 is Br, Cl, I or OTf and R2 is COOH or C1-3 alkyl ester, and when R2 is C1-3 alkyl ester, the method of forming NAPA also comprises hydrolysis of the C1-3 alkyl ester to form an acid. In one aspect, R1 may be Cl. In another aspect, R1 may be Br. In a further aspect, R1 may be I. In a further aspect, R1 may be OTf. In one aspect of the press

[343] In one aspect, R2 may be C1-3 alkyl ester. In one aspect, R2 may be COOCH3 or COOCH2CH3. In one aspect,

[344] The base may comprise a strong inorganic base. In one aspect, the base may be selected from the group consisting of KOtBu, NaOtBu, LiOtBu, Mg(OtBu)2, Al(OtBu)3, NaOSiMe3, Cs2CO3, potassium bis(trimethylsilyl)amide ("KHMDS"), sodium bis (trimethylsilyl)amide (“NaHMDS”), lithium bis(trimethylsilyl)amide (“LiHMDS”), and combinations thereof. In one aspect, the base comprises Mg(OtBu)2 and one of NaOtBu and KOtBu, or both. In another aspect, the base comprises Mg(OtBu)2 and one of NaOtBu and KOtBu. The ratio of Mg(OtBu)2 to NaOtBu or KOtBu can be in a range of about 1.5:1 to about 2.5:1, or about 2:1. Mixing can occur at a temperature in a range of 20°C to 80°C, or 25°C to 60°C, or 25°C to 45°C, or 25°C to 35°C. In one aspect, hydrolysis occurs under acidic conditions. The NAPA yield may be at least about 80%, or at least about 90%, or at least about 95%, or at least about 97%. The purity of NAPA may be at least about 95%, or at least about 97%, or at least about 99%, or at least about 99.5%, or about 100%. The optical purity of NAPA is at least about 90%, or at least about 95%, or at least about 97%, or at least about 99%, or at least about 99.5% ee.

[345] The present disclosure provides methods in which PIRH is formed by (i) mixing and a catalyst, under conditions sufficient to form an intermediate: wherein: (a) Y is F, Cl, Br, I or OTf, and Z comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin or silicon; or (b) Y comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin or silicon, and Z is F, Cl, Br, I or OTf; and (ii) mixing of and H2NNH2, under conditions sufficient to form PIRH:

[346] In one aspect, the catalyst comprises palladium (0), palladium (II), nickel, copper or iron. In a further aspect, the catalyst comprises palladium (0) or palladium (II). In another aspect, the catalyst comprises Pd2(dba)3, Pd(PPh3), a Pd catalyst having at least one phosphine ligand, PEPPSI-SIPr, or a paladacycle selected from the group consisting of a DavePhos, an XPhos, an SPhos, a JohnPhos, a RuPhos, a BrettPhos, a JackiePhos, a CPhos, and combinations thereof. In one aspect, the catalyst comprises an X-Phos paladacycle. The methods further provide that mixing in step (i) can occur in the presence of a base. In one aspect, the base is selected from the group consisting of KPO4, CsF, Cs2CO3, and combinations thereof. In the method described above, Y may be Cl, Br, I or OTf, and Z may comprise boron, magnesium, zinc, zirconium, tin or silicon. In one aspect, Y may be Cl. In another aspect, Y may be Br. In a further aspect, Y may be I. In another aspect, Y may be OTf. Z may comprise boronic acid, boronic ester or boronate. In one aspect, Z is a boronic acid. In another aspect, Z is a boronic ester selected from pinacolborane and catecholborane. In a further aspect, Z is a boronate selected from the group consisting of 9-borabicyclo[3.3.1]nonane (“9-BBN”), an N-methyliminodiacetic acid boronate (“MIDA boronate”), and 2-hydroxy- 4,4,5,5-tetramethyl-2-(1-methyl-1H-pyrazol-4-yl)-1,3,2-dioxaborolan-2-uide: In one aspect, Z is Z may comprise magnesium, zinc, zirconium, tin Y may comprise boron, magnesium, zinc, zirconium, tin or silicon, and Z is Cl, Br, I or OTf. In one aspect, Z may be Cl. In another aspect, Z may be Br. In another aspect, Z may be I. In a further aspect, Z is OTf. Y may comprise boronic acid, boronic ester, or boronate. In one aspect, Y is a boronic acid. In another aspect, Y is a boronic ester selected from pinacolborane and catecholborane. In a further aspect, Y is a boronate selected from the group consisting of 9-borabicyclo[3.3.1]nonane ("9-BBN"), an N-methyliminodiacetic acid boronate ("MIDA boronate"), and 2-hydroxy- 4,4,5,5-tetramethyl-2-(1-methyl-1H-pyrazol-4-yl)-1,3,2-dioxaborolan-2-uide:

[347] In one aspect, Y is

[348] In one aspect, Y may comprise magnesium, zinc, zirconium, tin or silicon.

[349] The present disclosure reveals that the mixing step in (i) occurs in a solvent selected from the group consisting of dioxane, water, toluene, tetrahydrofuran, 2-methyltetrahydrofuran, n-heptane, and combinations thereof. In one aspect, the solvent comprises 2-methyltetrahydrofuran. In one aspect, mixing in step (i) occurs in the presence of a phase transfer catalyst. The phase transfer catalyst may comprise, for example, a quaternary ammonium salt. In another aspect, the phase transfer catalyst comprises tetrabutylammonium bromide (“TBAB”). In one aspect, mixing in step (i) may occur in a solvent comprising alcohol and water. The alcohol may be selected from the group consisting of 1-butanol, 2-butanol, and combinations thereof. In one aspect, mixing in step (i) occurs at a temperature in a range of 60°C to 80°C, or 65°C to 75°C. The yield of the intermediate may be at least about 80%, or at least about 90%, or at least about 95%, or at least about 97%. The purity of the intermediate is at least about 97%, or at least about 98%, or at least about 99%. In one aspect, the hydrazine may be present in an amount of at least about 1 equivalent, or at least about 2 equivalents, or at least about 3 equivalents, or at least about 4 equivalents, or at least about 5 equivalents, or at least about 6 equivalents, or at least about 7 equivalents. In another aspect, hydrazine may be present in an amount of at least about 3 equivalents, or at least about 4 equivalents, or at least about 5 equivalents, or at least about 6 equivalents.

[350] In one aspect, mixing in step (ii) may occur at a temperature of at least 70°C, or at least 80°C, or at least 90°C, or at least 100°C, or at least 110°C. It is provided that mixing in step (ii) can take place in a solvent comprising water and alcohol. The alcohol may be selected from the group consisting of methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, and combinations thereof. In one aspect, the solvent comprises water and methanol. The yield of PIRH is at least about 90%, or at least about 95%, or at least about 97%, or at least about 99%. In one aspect, the purity of PIRH may be at least about 97%, or at least about 99%, or at least about 99.5%, or about 100%.

[351] The present disclosure provides methods in which NAPH is formed by: (i) mixing a methylnicotinate of Formula (I): wherein R3 is Cl, Br or 1, and R^ is alkyl; with 1,3,5-triazine, and a base, under conditions sufficient to form naphthyridinone of Formula (II): (ii) mixing the naphthyridinone of Formula (II) with methoxyethanol, a base, and a copper catalyst (I), under conditions sufficient to form NAPH:

[352] In one aspect, R3 can be selected from the group consisting of Br, Cl and I. In one aspect, R4 can be a C1-4 alkyl. For example, R4 can be selected from the group consisting of Me, Et, n-Pr and n-Bu. In a further aspect of the present disclosure, the copper (I) catalyst can be selected from the group consisting of CuBr, CuBr-DMS, Cu(OAc), Cu(OTf), and combinations thereof. In one aspect, the copper (I) catalyst also comprises a ligand. In one aspect, the ligand is selected from the group consisting of one of 1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline, or both. In a further aspect of the present disclosure, the base in step (i) can be selected from the group consisting of CS2CO3, KOtBu, K3PO4, K2CO3, and combinations thereof. In one aspect, the basis is CS2CO3 or KOtBu. In a further aspect of the present disclosure, mixing in step (i) can occur in a polar aprotic solvent. In one aspect, the solvent may comprise dimethyl sulfoxide or dimethylacetamide. The present disclosure provides that mixing in step (i) can occur at a temperature in a range of about 15°C to about 100°C, or about 80°C. In one aspect, the base in step (ii) may be selected from the group consisting of KH, NaH, LiH, KOiBu, NaOiBu, LiOiBu, BuLi, HexLi, Cs2CO3, lithium bis(trimethylsilyl)amide ("LiHMDS"), sodium bis(trimethylsilyl)amide (“NaHMDS”), potassium bis(trimethylsilyl)amide (“KHMDS”), lithium diisopropylamide (“LDA”), lithium tetramethylpiperidine (“LiTMP), LiOH, NaOH, KOH, CsOH, and combinations thereof. In one aspect, the base in step (ii) may be selected from the group consisting of CS2CO3, LiOiBu, LiHMDS, KOiBu, and combinations thereof. In one aspect, mixing in step (ii) may occur in an ether solvent having a boiling point above about 85°C. In one aspect, the solvent may be selected from the group consisting of pure 2-methoxyethanol, diglyme, dioxane, and combinations thereof. Mixing in step (ii) may occur at a temperature in a range of about 50°C to about 130°C, about 80°C to about 120°C, or about 114°C. The yield of NAPH can be at least about 56%, 75%, 85% or 95%. NAPH has a purity of at least about 90%, 95% or 97%.

[353] The present disclosure provides the methods, in which NAPH is formed by: (i) mixing protected N-(3-formyl-4-amino-2-alkoxy)pyridine: where PG is a protecting group and R8 is alkyl, with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: and base, under conditions sufficient to form a naphthyridine of Formula (III): (ii) acidification of naphthyridine of Formula (III), under conditions sufficient to form NAPH:

[354] In one aspect, PG is selected from the group consisting of PivCl, PivBr and Piv anhydride. In one aspect, R8 is a C1-4 alkyl. R8 can be CH3. In another aspect, may be present in an amount of about 1 equivalent to about 5 equivalents, or about 1.2 equivalents. In a further aspect, the base is selected from the group consisting of NaOH, KOH, KPO4, LiOH, CsOH and RbOH, and a combination thereof. In one aspect, mixing occurs in a water-soluble solvent selected from the group consisting of methanol, ethanol, isopropanol, acetonitrile, tetrahydrofuran, dioxane, 2-methoxyethanol, t-BuOH, 2-BuOH, trifluoroethanol, water, and mixtures thereof. Mixing can occur at a temperature in a range of about 40°C to 90°C, or about 60°C. In one aspect, the conditions sufficient to form NAPH in step (ii) comprise acidic conditions. The acidic conditions may comprise an acid selected from HCl, HBr, H2SO4, CH3SO3H, H3PO4, trifluoromethanesulfonic acid, trifluoroacetic acid, tosylic acid, and combinations thereof. In one aspect, the acid may be present in an amount ranging from about 1 equivalent to about 10 equivalents, or about 1.2 equivalents. Acidification can occur at a temperature in a range of 50°C to 100°C, or about 65°C. The yield of NAPH may be at least about 80%, at least about 90%, or at least about 95%. The purity of NAPH is at least about 80%, at least about 30%, or at least about 10%.

[355] In one aspect, a protected N-(3-formyl-4-amino-2-alkoxy)pyridine is formed by mixing a protected N-(4-amino-2-alkoxy)pyridine: with a lithium reagent, under conditions sufficient to form the protected N-(3-formyl-4-amino-2-alkoxy)pyridine:

[356] In one aspect, the lithium reagent may be selected from the group consisting of n-hexyl lithium, n-butyl lithium, s-butyl lithium, lithium bis(trimethylsilyl)amide (“LiHMDS”), lithium diisopropyl amide ( “LDA”), lithium tetramethylpiperidine (LiTMP), and combinations thereof. In one aspect, the lithium reagent comprises one of n-hexyl lithium and n-butyl lithium, or both. Mixing can occur at a temperature in a range of about -50°C to 25°C, or about -30°C to -10°C. The yield of a protected N-(3-formyl-4-amino-2-alkoxy)pyridine may be at least about 80% or at least about 85% or at least about 90%. The purity of the protected N-(3-formyl-4-amino-2-alkoxy)pyridine may be at least about 95%, or at least about 60%, or at least about 30%.

[357] In one aspect, the protected N-(4-amino-2-alkoxy)pyridine is formed by mixing 2-alkoxy-pyridin-4-ylamine: with base and a pivaloyl compound of Formula (IV): under conditions sufficient to form protected N-(4-amino-2-alkoxy)pyridine, wherein R5 is Cl, Br or OC(O)alkyl. In one aspect, R5 can be selected from the group consisting of Cl, Br and OC(O)alkyl. In a further aspect, alkyl can be selected from the group consisting of Me, Et, Pr, iPr, n-Bu, sec-Bu and tert-Bu. Mixing can occur at a temperature in a range of about -30°C to 50°C, or about 0°C. The yield of the protected N-(4-amino-2-alkoxy)pyridine is at least about 85%, at least about 90%, or at least about 95%. In one aspect, N-(4-amino-2-alkoxy)pyridine has a purity of at least about 90%, at least about 80%, or at least about 60%.

[358] In one aspect of the present disclosure, 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: is formed by contact 2-(2-methoxyethoxy)acetaldehyde: with HSO3-, S2O52-, or a combination thereof, under conditions sufficient to form 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate. In one aspect, HSO3- and S2O52- have a counterion selected from the group consisting of Li+, K+, Na+, Me4N+, Et4N+, Bu4N+, and combinations thereof. In a further aspect, 2-(2-methoxyethoxy)acetaldehyde is formed by oxidation of 2-(2-methoxyethoxy)-1-ethanol: with an oxidizing agent. The oxidizing agent may be selected from the group consisting of oxalyl chloride, pyridinium chlorochromate (“PCC”), pyridinium dichromate (“PDC”), dimethyl sulfoxide (“DMSO”) activated with a sulfur trioxide-pyridine complex, and combinations thereof. Oxidation can occur in the presence of a base, for example. The base may be selected from the group consisting of triethylamine, DIPEA, N-methylmorpholino, and combinations thereof. In one aspect, the base may comprise triethylamine. Oxidation can occur in a solvent comprising methoxyethanol.

[359] In one aspect, 2-(2-methoxyethoxy)acetaldehyde is formed by: (i) mixing and a strong foundation to form wherein R6 is Cl, Br, I or cyclic diol protecting groups; and R7 is C1-4 alkyl; and (ii) hydrolysis of to form 2-(2-methoxyethoxy)acetaldehyde:

[360] In one aspect of the present disclosure, R6 can be selected from the group consisting of Cl, Br, I, ethylene glycol and 1,3-propanediol. Furthermore, each R7 independently can be selected from the group consisting of CH3, CH2CH and CH2CH2CH. In one aspect, R7 may be CH2CH3. In one aspect, the strong base may be present in an amount in a range of about 1 equivalent to about 1.5 equivalents. In one aspect, the strong base is present in an amount of about 1.2 equivalents. In one aspect, the strong base is selected from the group consisting of NaH, LiH, LiOt-Bu, BuLi, hexLi, NaOt-Bu, KOt-Bu, KH, LiOH, and combinations thereof. Mixing can occur over a temperature range of about 100°C to about 120°C, or about 110°C. Hydrolysis can occur under acidic conditions. The yield of the sulfonate may be at least about 50%, at least about 60%, at least about 70%, or at least about 80%. It is contemplated that the sulfonate has a purity of at least about 40%, at least about 50%, or at least about 60%.

[361] The present disclosure provides a method comprising: (i) mixing a methylnicotinate of Formula (I): wherein R3 is Cl, Br or I, and R4 is alkyl; with 1,3,5-triazine and a base, under conditions sufficient to form naphthyridinone of Formula (II): (ii) mixing the naphthyridinone of Formula (II) with methoxyethanol, a base and a copper catalyst (I), under conditions sufficient to form 3-(2-methoxyethoxy)-1,6-naphthyridin-5((5H)- ona (“NAPH”):

[362] The present disclosure provides a method comprising mixing protected N-(4-amino-2-alkoxy)pyridine: with a lithium reagent, under conditions sufficient to form protected N-(3-formyl-4-amino-2-alkoxy)pyridine:

[363] The present disclosure provides a method comprising mixing the protected N-(3-formyl-4-amino-2-alkoxy)pyridine: with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: and base, under conditions sufficient to form a naphthyridine of Formula (III):

[364] In one aspect, the method also comprises acidifying the naphthyridine of Formula (III), under conditions sufficient to form 3-(2-methoxyethoxy)-1,6-naphthyridin-5((5H)-one ("ΝΑΡΗ ”):

[365] In one aspect, the present disclosure provides a method comprising: (i) mixing 4-amino-2-alkoxypyridine: wherein R8 is an alkyl group, with a pivaloyl compound of Formula (IV): where R5 is Cl, Br or OC(O)alkyl, and base, under conditions sufficient to form N-(2-alkoxypyridin-4-yl)pivalamide: (ii) mixing N-(2-alkoxypyridin-4-yl)pivalamide with a lithium reagent, under conditions sufficient to form the protected N-(3-formyl-4-amino-2-alkoxy)pyridine: (iii) mixing protected N-(3-formyl-4-amino-2-alkoxy)pyridine with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: and base, under sufficient conditions to form a naphthyridine of Formula (III): (iv) acidifying the naphthyridine of Formula (III), under conditions sufficient to form 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“NAPH”):

[366] The present disclosure further provides a method comprising contacting 2-(2-methoxyethoxy)acetaldehyde: with HSO3-, S2O52-, or a combination thereof, under conditions sufficient to form 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate:

[367] The present disclosure provides a method comprising crystallizing Compound A: in a solution of alcohol and water, under conditions sufficient to form a monohydrate form of Compound A:

[368] The present disclosure provides a method comprising: (i) mixing 3-(2-methoxyethoxy)-1,6-naphthyridin-5((5H)-one (“NAPH”): and a basis, under conditions sufficient to form NAPA: wherein R1 is Br, Cl, I or OTf, and R2 is COOH or C1-3 alkyl ester, and when R2 is C1-3 alkyl ester, the method of forming NAPA also comprises hydrolysis of C1-3 alkyl ester to form an acid; (ii) mixing NAPA with 3-fluoro-2-hydrazinyl-5-(1-methyl-7H-pyrazol-4-yl)pyridine (“PIRH”): and a coupling reagent, and under conditions sufficient to form (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-(3 -(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl)propanehydrazide (“HYDZ”): (iii) reaction of HYDZ under conditions sufficient to form (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4-yl)- [1,2,4]triazol[ 4,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“A”):

[369] In one aspect, the reaction comprises contacting HYDZ with a thiophosphetan compound. In another aspect, the reaction comprises contacting HYDZ with a phosphorus (V) dehydrating agent.

[370] The description presented above is given only for clarity of understanding, and no unnecessary limitations should be implied from it, insofar as modifications within the scope of the invention may be evident to those skilled in the art.

[371] Throughout this specification and the following claims, unless the context requires otherwise, the word “comprises” and variations such as “understand” and “which comprises” will be understood to imply the inclusion of an established integer or step or group of integers or steps, but not to the exclusion of any other integer or step or group of integers or steps.

[372] Throughout this specification, when compositions are described as including components or materials, it is contemplated that the compositions may also consist basically of, or consist of, any combination of the aforementioned components or materials, unless otherwise described. Likewise, when methods are described as including particular steps, it is contemplated that the methods may also consist primarily of, or consist of, any combination of the aforementioned steps, unless otherwise described. The invention illustratively disclosed herein may be adequately practiced in the absence of any element or step that is not specifically disclosed herein.

[373] The practice of a method disclosed herein, and its individual steps, can be done manually and/or with the assistance or automation provided by electronic equipment. Although processes have been described with reference to particular embodiments, those skilled in the art will quickly note that other forms of carrying out the acts associated with the methods may be used. For example, the order of several of the steps may be changed without departing from the scope or spirit of the method, unless otherwise described. Furthermore, some of the individual steps may be combined, omitted, or subdivided into additional steps.

[374] All patents, publications and references cited herein are fully incorporated by reference in this specification. In case of conflict between the present disclosure and incorporated patents, publications and references, the present disclosure shall prevail.

Claims (32)

1. Method, characterized by the fact that it comprises (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-(3-( 2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl) propanehydrazide (“HYDZ”): to a dehydration reaction with either a thiophosphetetan compound or a phosphorus (V) dehydrating agent, thus forming (R)-6-(1-(8-fluoro-6-(1-methyl-1H-pyrazol-4- yl)-[1,2,4]triazol[4,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“A ”): 2. Method according to claim 1, characterized by the fact that the thiophosphetan compound comprises a 2,4-bis(aryl)-1,3-dithia-2,4-diphosphetan 2,4-disulfide compound. 3. Method according to claim 2, characterized by the fact that the 2,4-bis(aryl)-1,3-dithia-2,4-diphosphetan 2,4-disulfide compound is: 4. Method according to claim 1, further comprising contacting Compound A with a water-rich solvent having a pH of at least 7 to form a monohydrate form of compound A. 5. Method according to claim 1, characterized by the fact that the dehydrating agent comprises a compound having a structure: wherein each L is independently C1-6 alkyl, O-C1-6 alkyl, aryl, O-aryl, Br, Cl, or I; and R1 is Cl, Br or I. 6. Method according to claim 5, characterized by the fact that each L is selected from the group consisting of Me, Et, t-Bu, O-Me, O-Et, O-t-Bu, phenyl, O-phenyl , Br and Cl. 7. Method according to claim 1, further characterized by contacting Compound A with an acid under conditions sufficient to form a salt of compound A. 8. Method according to claim 7, characterized in that the acid is selected from the group consisting of hydrochloric acid, phosphoric acid, camphorsulfonic acid, 2-naphthylsulfonic acid, methanesulfonic acid, benzenesulfonic acid and derivatives thereof, succinic acid , tartaric acid, fumaric acid, maleic acid, and combinations thereof. 9. Method according to claim 1, further comprising crystallizing Compound A in a solution comprising alcohol and water to form a monohydrate form of Compound A: 10. Method according to claim 1, characterized by the fact that HYDZ is formed by reaction of acid (R)-2-(3-(2-methoxyethoxy)-5-oxo-1,6-naphthyridin-6 (5H)-yl)propanoic acid (“NAPA”): With 3-fluoro-2-hydrazinyl-5-(1-methyl-7H-pyrazol-4-yl)pyridine (“PYRH”): and a binding reagent, and under conditions sufficient to form HYDZ: 11. Method according to claim 10, characterized by the fact that NAPA is a salt comprising HCl, HBr, sulfonic acid, diisopropylamine or potassium. 12. Method according to claim 11, characterized in that the sulfonic acid salt is selected from the group consisting of 2-naphthalene sulfonic acid, 1-naphthalene sulfonic acid, m-xylene sulfonic acid, p-toluene acid sulfonic acid, benzenesulfonic acid, 2-nitrobenzenesulfonic acid, 2,5-dichlorobenzenesulfonic acid, (-)-10-camphorsulfonic acid, (+)-camphor-10-sulfonic acid, p-chlorobenzenesulfonic acid, methanesulfonic acid, and combinations thereof. 13. The method of claim 10, wherein the binding reagent comprises a reagent selected from the group consisting of a carbodiimide reagent, a phosphonium reagent, a uronium reagent, an immonium reagent, a imidazolium reagent, an organophosphorus reagent, an acid chloride reagent, a chloroformate reagent, a pyridinium reagent, and combinations thereof. 14. Method according to claim 10, characterized by the fact that the reaction occurs in the presence of a tertiary amine base selected from the group consisting of N,N-diisopropylethylamine (“DIEA”), triethylamine (“TEA”) , N-methylmorpholino (“NMM”), and combinations thereof. 15. Method, according to claim 10, characterized by the fact that NAPA is formed by mixing 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“NAPH”): and a basis for forming NAPA: wherein R1 is Br, Cl, I or OTf and R2 is COOH or C1-3 alkyl ester, and when R2 is C1-3 alkyl ester, the method of forming NAPA also comprises hydrolysis of the C1-3 alkyl ester to form an acid. 16. Method according to claim 15, characterized by the fact that R2 is COOH. 17. Method according to claim 15, characterized by the fact that the base is selected from the group consisting of KOtBu, NaOtBu, LiOtBu, Mg(OtBu)2, Al(OtBu)3, NaOSiMe3, Cs2CO3, potassium bis( trimethylsilyl)amide (“KHMDS”), sodium bis(trimethylsilyl)amide (“NaHMDS”), lithium bis(trimethylsilyl)amide (“LiHMDS”), 18. Method, according to claim 10, characterized by the fact that the PIRH is formed by: (i) mixing of and a catalyst, to form an intermediate: wherein: (a) Y is F, Cl, Br, I or OTf, and Z comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin or silicon; or (b) Y comprises boronic acid, boronic ester, magnesium, zinc, zirconium, tin or silicon, and Z is F, Cl, Br, I or OTf; and (ii) mixture of and H2NNH2, under conditions sufficient to form PYRH: 19. Method according to claim 18, characterized in that the catalyst comprises palladium (0), palladium (II), nickel, copper, iron, or combinations thereof. 20. Method, according to claim 18, characterized by the fact that the mixing in step (i) occurs in the presence of a base. 21. Method according to claim 18, characterized by the fact that Y is Cl, Br, I or OTf, and Z comprises boron, magnesium, zinc, zirconium, tin or silicon. 22. Method according to claim 21, characterized in that Z comprises boronic acid, boronic ester or boronate. 23. Method according to claim 18, characterized in that Y comprises boron, magnesium, zinc, zirconium, tin or silicon, and Z is Cl, Br, I or OTf. 24. Method according to claim 23, characterized in that Y comprises boronic acid, boronic ester or boronate. 25. Method, according to claim 18, characterized by the fact that the mixing in step (i) occurs in the presence of a phase transfer catalyst. 26. Method, according to claim 15, characterized by the fact that NAPH is formed by: (i) mixing a methylnicotinate of Formula (I): wherein R3 is Cl, Br or I, and R4 is alkyl; with 1,3,5-triazine, and a base, to form naphthyridinone of Formula (II): (ii) mixing the naphthyridinone of Formula (II) with methoxyethanol, a base, and a copper catalyst (I), under conditions sufficient to form NAPH: 27. Method according to claim 26, characterized by the fact that the copper catalyst (I) is selected from the group consisting of CuBr, CuBr-DMS, Cu(OAc), Cu(OTf) and combinations thereof. 28. Method according to claim 26, characterized by the fact that the base in step (i) is selected from the group consisting of CS2CO3, KOtBu, K3PO4, K2CO3, and combinations thereof. 29. Method, according to claim 15, characterized by the fact that NAPH is formed by: (i) mixture of protected N-(3-formyl-4-amino-2-alkoxy)pyridine: where PG is a protecting group and R8 is alkyl, with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: and base, under conditions sufficient to form a naphthyridine of Formula (III): (ii) acidification of naphthyridine of Formula (III), under conditions sufficient to form NAPH: 30. Method characterized by comprising: (i) mixing a methylnicotinate of Formula (I): wherein R3 is Cl, Br or I, and R4 is alkyl; with 1,3,5-triazine, and a base to form naphthyridinone of Formula (II): (ii) mixing the naphthyridinone of Formula (II) with methoxyethanol, a base, and a copper catalyst (I), under conditions sufficient to form 3-(2-methoxyethoxy)-1,6-naphthyridin-5((5H) -one (“NAPH”): 31. Method characterized by comprising: (i) mixture of 4-amino-2-alkoxypyridine: wherein R8 is an alkyl group, with a pivaloyl compound of Formula (IV): where R5 is Cl, Br or OC(O)alkyl, and base to form N-(2-alkoxypyridin-4-yl)pivalamide: (ii) mixing N-(2-alkoxypyridin-4-yl)pivalamide with a lithium reagent, to form the protected N-(3-formyl-4-amino-2-alkoxy)pyridine: (iii) mixture of N-(3-formyl-4-amino-2-alkoxy)pyridine protected with 1-hydroxy-2-(2-methoxyethoxy)ethane-1-sulfonate: and base to form a naphthyridine of Formula (III): (iv) acidifying the naphthyridine of Formula (III), under conditions sufficient to form 3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (“NAPH”): 32. Method characterized by comprising: (i) mixture of 3-(2-methoxyethoxy)-1,6-naphthyridin-5((5H)-one (“NAPH”): and a basis, under conditions sufficient to form NAPA: wherein R1 is Br, Cl, I or OTf, and R2 is COOH or C1-3 alkyl ester, and when R2 is C1-3 alkyl ester, the method of forming NAPA further comprises hydrolysis of the C1-3 alkyl ester to form an acid; (ii) mixing NAPA with 3-fluoro-2-hydrazinyl-5-(1-methyl-7H-pyrazol-4-yl)pyridine (“PYRH”): and a coupling reagent, to form (R)-N'-(3-fluoro-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-(3-(2- methoxyethoxy)-5-oxo-1,6-naphthyridin-6(5H)yl)propanehydrazide (“HYDZ”): (iii) subjecting HYDZ to the dehydration reaction with either a thiophosphethane compound or a phosphorus (V) dehydrating agent, thus forming (R)-6-(1-(8-fluoro-6-(1-methyl- 1H-pyrazol-4-yl)-[1,2,4]triazol[4,3-a]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H )-one (“A”):