CN104231008B - The Regioselective synthesis of nucleoside medicine 5 ' bit amino acid esters - Google Patents

Abstract

The invention relates to a regioselective synthesis method of nucleoside drug 5'-position amino acid esters with structural characteristics as shown in general formula I and pharmaceutically acceptable salts thereof. Wherein Base, R, R ₂ , and R ₃ are as defined in the instructions. This method selectively protects the 5'-position hydroxyl of nucleoside drugs by using triarylmethyl (Ar ₃ C-), and then uses allyloxycarbonyl (allyloxycarbonyl , AOC) to protect the base part of nucleoside drugs and all other active sites in the sugar structure part, and then selectively remove the triarylmethyl group under acidic conditions, and then condense with the amino acid protected by Boc, and in the nucleoside drug molecule The 5'-position of the catalyst is selectively esterified, followed by palladium-catalyzed removal of AOC, and finally Boc is removed under acidic conditions to form the corresponding salt. The method of the invention has the advantages of high yield, easy separation and purification of the obtained product, and is more suitable for industrial production.

Description

Regioselective synthesis method of 5'-position amino acid esters of nucleoside drugs

technical field

The invention belongs to the technical field of medicine, and relates to a regioselective synthesis method of amino acid ester at the 5'-position of nucleoside drugs by adopting the protection strategy of triarylmethyl group and allyloxycarbonyl group.

Background technique

Nucleoside drugs are widely used in anti-virus and anti-tumor clinically. This type of drug is obtained by slightly changing the structure of metabolites such as purine and pyrimidine required in DNA synthesis by using the principle of bioelectronic isosteres. drug. After administration, it is activated by the intracellular triphosphorylation process, and by inhibiting the enzymes involved in the synthesis of purine or pyrimidine nucleotides, the intracellular triphosphate base deoxynucleotide synthesis is disordered, incorporated into DNA or RNA macromolecules, and interferes with cell replication Competitive inhibition of DNA synthesis-related enzymes and other three main functions, specifically interferes with the metabolism of nucleic acids, prevents cell division and reproduction, and ultimately leads to tumor cell death or inhibits virus replication. However, due to the high polarity, poor membrane permeability, and low metabolic stability of most nucleoside drugs, the oral bioavailability of these drugs is low. In response to this problem, the current research hotspot is to use amino acids or oligopeptides with specific spatial structures to modify the parent drug to make oligopeptide transporter (The Peptide Transporter1, PepT1) targeted prodrugs to improve its membrane transport, thereby improving its oral bioavailability. Such prodrugs that have been successfully marketed include: Valaciclovir and Valganciclovir, whose oral bioavailability has increased from 10% to 20% and 6% to 55% and 61%, respectively. %.

He Zhonggui et al. (Molecular Pharmaceuticals, 2009, 6(1), 315～325) used carbobenzyloxy chloride (Cbz-Cl) to selectively protect the 4-position of cytarabine, arainosylcytosine, ara-C The amino group is then condensed with the amino acid protected by tert-butoxyformyl (Boc) to form an ester under the catalysis of carbonyldiimidazole (CDI), and then catalyzed by palladium on carbon (Pd/C) to remove the Cbz protecting group of the 4-amino group group, and finally remove Boc under acidic conditions and form hydrochloride, and synthesize a series of cytarabine 5'-amino acid ester derivatives (CN101250209). However, in this route, first of all, the selectivity of the reaction when using Cbz to protect the 4-amino group is poor, and more by-products are produced, which must be separated and purified by column chromatography, which is inconvenient to operate and has a low yield; secondly, when protected with Boc When amino acids are acylated into esters, the reaction selectivity of the three hydroxyl groups of the sugar in cytarabine molecule is poor, and there are more by-products. In addition to the required 5'-position monoester, there are similar amounts of positional differences. The 3'-position monoester of the conformation is formed at the same time, and the Rf values of the two on the silica gel plate are basically the same. It is difficult to separate them by ordinary silica gel chromatography, and only a small amount of samples can be obtained by means of preparative liquid phase separation, which cannot satisfy in-depth research. The preparation of a large number of samples is not suitable for industrial production (as shown in Scheme 1).

Gallop, M.A. et al. (WO2004041203) used trimethyl chlorosilane (trimethyl chlorosilane, TMSCl) to protect gemcitabine (gemcitabine) 4-position amino group and 3', 5'-position hydroxyl group, and then used 1-(allyloxycarbon oxygen base)-1H-benzotriazolyl carbonate (allyl1-benzotriazolyl carbonate, AOC-OBt) selectively protects its 4-amino group, and then selectively removes TMS under acidic conditions, and reacts with Boc-protected amino acid in 4-dimethyl Dimethylaminopyridine (4-dimethylaminopyridine, DMAP) and dicyclohexylcarbodiimide (dicyclohexylcarbodiimide, DCC) are condensed into esters, followed by palladium-catalyzed removal of allyloxycarbonyl groups, and finally Boc is removed under acidic conditions to form hydrochloride , synthesized a series of amino acid ester derivatives at the 5'-position of gemcitabine. Similar to the synthesis route of cytarabine amino acid ester by Sun Yongbing et al., it is also difficult to control the selective formation of 5'-position monoester in the process of condensation and esterification, so as to effectively prevent the formation of 3'-position isomers, not only The yield is low, and it is extremely difficult to separate and purify, which cannot meet the preparation of a large number of samples (as shown in Scheme 2).

Scheme 2. The selectivity problem in the synthesis of gemcitabine 5'-amino acid ester by Gallop method

In summary, the reported synthetic routes of 5'-amino acid ester prodrugs of this type of nucleoside drugs, due to the lack of selective protection of multiple hydroxyl groups of sugars in nucleoside molecules, 5'- At the same time as the amino acid ester at the 3'-position, it is also accompanied by a considerable amount of 3'-positional isomers, which are difficult to separate and purify, and are not suitable for industrial production. Therefore, the selective synthesis of 5'-amino acid esters of such nucleoside drugs is very necessary.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for regioselective synthesis of amino acid esters at the 5'-position of nucleoside drugs.

The present invention is achieved through the following technical solutions:

Use triarylmethyl (Ar ₃ C-) to selectively protect the 5'-position hydroxyl of nucleoside drugs, and then use allyloxycarbonyl (allyloxycarbonyl, AOC) to protect the base part and sugar structure part of nucleoside drugs For all other active sites, the triarylmethyl group is selectively removed under acidic conditions, and then condensed with the Boc-protected amino acid to selectively form an ester at the 5'-position of the nucleoside drug molecule, and then palladium-catalyzed removal of AOC , and finally remove Boc under acidic conditions and form the corresponding salt.

Concrete reaction steps are as follows:

(1) general formula VII and triaryl methylation reagent form ether and make general formula VI;

(2) General formula VI is condensed with allyloxycarbonylating reagent to prepare general formula V;

(3) The general formula V selectively removes the 5'-position triarylmethyl protecting group under acidic conditions to obtain the general formula IV;

(4) The general formula IV is condensed with the corresponding Boc-protected α-amino acid to form an ester to obtain the general formula III;

(5) General formula III removes all AOC protecting groups under homogeneous palladium catalyzed conditions and prepares general formula II;

(6) General formula II removes all AOC protecting groups under homogeneous palladium catalyzed conditions to prepare general formula I.

in:

The structural formulas of general formulas I to VII are respectively:

Wherein, the base Base part is natural pyrimidine bases, purine bases, or their structurally modified bases, and the base nucleosides corresponding to the base Base are Cytarabine (Cytarabine), Gemcitabine (Gemcitabine) ), Vidarabine, PSI-6130, Clofarabine, Thiarabine, Triciribine; X is a carbon atom, oxygen or sulfur atom; R ₂ or R ₃ is a hydrogen atom, Hydroxyl, halogen atom, azido, methyl or trifluoromethyl, and exist in any configuration of R _- type or S-type, R2 or _R3 can also be a dihalogen atom such as a difluorine atom, Fluorine and chlorine atoms or any combination of the above two atoms or atomic groups; the amino acid at the 5'-position RCH(NH ₂ )COO-ester bond comes from various natural or artificially modified α-amino acids RCH(NH ₂ )COOH , wherein the amino acids are glycine, alanine, valine, leucine, isoleucine, phenylalanine, proline, butyrine, and in the form of L-form, D-form or racemate exist.

According to the selective synthesis method, the 5'-position amino acid esters of basic nucleosides and their pharmaceutically acceptable salts are obtained, preferably the 5'-position amino acid ester dihydrochloride of PSI-6130.

In step (1), the triaryl methylation reagent is triphenylmethyl chloride (TriphenylmethylChloride, TrCl), trifluoromethanesulfonate trityl ester (Triphenylmethyl triflate TrOTf), bis(p-methoxyphenyl) Phenylmethyl chloride (4,4'-Dimethoxytrityl Chloride, DMTr-Cl), trimethoxytrityl chloride (4,4',4''-trimethoxytrityl Chloride, TMTr-Cl), preferably trityl Triphenylmethylchloride (TrCl); the reaction solvent is pyridine, dichloromethane, dichloroethane, chloroform, benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxy Ethane, N,N-dimethylformamide, N,N-dimethylacetamide, or different combinations of the above solvents; the organic base used in the reaction is pyridine, dimethylaminopyridine, triethylamine, diisopropyl Ethylamine, N,N-dimethylaniline, or inorganic bases such as sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide; the reaction temperature is -20 ° C ~ solvent Reflux temperature; reaction time varies depending on the specific substrate.

In step (2), the allyloxycarbonylating reagent is 1-allyloxycarbonyl tetrazole (1-(Allyloxycarbonyl)tetrazole, AOC-Tet), 1-(allyloxycarbonyloxy)-1H - Benzotriazole (allyl1-benzotriazolyl carbonate, AOC-OBt), allyl chloroformate (allyl chloroformate, AOC-Cl), preferably allyl chloroformate (allyl chloroformate, AOC-Cl); the reaction solvent is dichloro Methane, dichloroethane, chloroform, benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, N,N-dimethylformamide, N, N-dimethylacetamide, or different combinations of the above solvents; the organic base used in the reaction is dimethylaminopyridine, triethylamine, diisopropylethylamine, N,N-dimethylaniline, pyridine, or Inorganic bases such as sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide; the reaction temperature is -20 ° C ~ solvent reflux temperature; the reaction time varies depending on the specific substrate.

In step (3), the acid is hydrogen chloride, formic acid, glacial acetic acid, trifluoroacetic acid, p-toluenesulfonic acid, and the acid is preferably hydrogen chloride; the solvent used for this reaction is selected from alcohols with 1 to 6 carbons such as methanol , ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, or different combinations of these solvents, or ether solvents such as diethyl ether, methyl tert-butyl ether, diisopropyl ether, Tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, 1,4-dioxane, or different combinations of these solvents, or ester solvents such as methyl acetate, ethyl acetate, butylacetate Esters, or water, or different combinations of the above solvents; the reaction temperature is -20 ° C ~ solvent reflux temperature; the reaction time varies depending on the specific substrate.

In step (4), the reaction condensing agent is selected from N,N'-dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide Hydrochloride (EDCI), carbonyldiimidazole (CDI), 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), 2-(7-Azobenzotriazole)-tetramethyluronium hexafluorophosphate (HBTU), 1-Hydroxy-7-azobenzotriazole (HOAt), 1-Hydroxybenzotriazole (HOBt), the preferred EDCI of described condensing agent; Catalyst is selected from 4-dimethylaminopyridine (DMAP), pyridine, triethylamine, diisopropylethylamine; This reaction solvent is selected from methylene dichloride, ethylene dichloride , chloroform, benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, 1,4-dioxane, N,N-dimethylformamide , N,N-dimethylacetamide, or different combinations of the above solvents; the reaction temperature is carried out at -20 ° C ~ solvent reflux temperature, preferably 0 ~ 45 ° C; the reaction time varies depending on the specific substrate.

In step (5), the optional palladium catalysts are tetrakis(triphenylphosphine)palladium [Pd(PPh ₃ ) ₄ ], palladium chloride (PdCl ₂ ), palladium acetate [Pd(OAc) ₂ ], tris(di benzylideneacetone) dipalladium [Pd ₂ (dba) ₃ CHCl ₃ ], the palladium catalyst is preferably tetrakis (triphenylphosphine) palladium; in order to increase the stability of the palladium catalyst, the above-mentioned catalyst and organic phosphine ligand Combined coordination; the neutral or weakly acidic nucleophiles selected for this reaction are Dimedone, 1,3-dimethylbarbituric acid (NDMBA), formic acid, acetic acid, primary amine, secondary amine and formic acid Or a mixture of carbonic acid [ammonium formate (HCOO ^- NH ₄ ⁺ ), n-butylammonium formate (HCOOH/n-BuNH ₂ ), diethylammonium formate (HCOOH/Et ₂ NH), diethylammonium carbonate [(Et ₂ NH ₂ ⁺ ) ₂ CO ₃ ^2- ], diethylammonium bicarbonate (Et ₂ NH ₂ ⁺ HCO ₃ ^- )], the nucleophile is preferably n-butylammonium formate (HCOOH/n-BuNH ₂ ); the reaction can be selected The solvent is selected from dichloromethane, 1,2-dichloroethane, chloroform, diethyl ether, methyl tert-butyl ether, diisopropyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxy Ethane, 1,4-dioxane, or different combinations of the above solvents, the solvent is preferably tetrahydrofuran; the reaction temperature is -20 ° C ~ solvent reflux temperature, preferably 0 ~ 45 ° C.

The reaction formula of step (6) is:

For the sake of clarity, when Base is cytarabine, the structures corresponding to general formulas I~VII are I ₁ ~VII ₁ , respectively, as shown below.

The method of the invention has the advantages of high yield, easy separation and purification of the obtained product, and is more suitable for industrial production.

detailed description

The following specific implementation examples are for more complete description of the present invention, and are not meant to limit the scope of the present invention as defined in the claims in any way.

Example 1: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 1 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-valine ester, I _1a )

Step 1: Under argon protection and cold water cooling, slowly add 256.5 g (0.92 mol) of trityl chloride to a mixture of 194.6 g (0.80 mol) of cytarabine (VII ₁ ) and 1500 mL of anhydrous pyridine, Note that the reaction system is fully stirred by mechanical stirring, and the feeding speed is controlled to gradually disperse or dissolve the added materials in the system. After the addition, continue to stir for 2h, then slowly warm up to 30°C and continue to react for 20h, and TLC detects that the reaction is complete.

Concentrate under reduced pressure to recover as much pyridine as possible in the reaction system, and then add 300 mL of absolute ethanol to the residue to fully disperse the content. The mixture was slowly poured into 5.0 L of ice water, stirred rapidly to thaw, and a white solid was precipitated.

Suction filtration, washing with water, and drying gave 480.5 g of light yellow crude product. The crude product was recrystallized with 1000 mL of ethyl acetate, filtered with suction, and the filtrate gradually precipitated a white solid after cooling. Stand overnight, filter with suction, and dry to obtain 462.2 g of white solid (VI ₁ ), yield 95.2%, mp 210-213°C.

¹ H NMR(d ₆ -DMSO)δ3.15(m,2H,5'-CH ₂ ),3.81(m,1H,4'-CH ₂ ),3.84(m,1H,2'-CH),3.88 (m,1H,3'-CH),5.32(d,1H,3'-OH),5.41(d,H,2'-OH),5.55(d,1H,J=7.4Hz,5-CH) ,6.05(d,1H,1'-H),7.00(s,2H,4-NH ₂ ),7.30(m,15H,Ph ₃ ),7.42(d,1H,J=7.4Hz,6-CH) ;

ESI-MS(m/z):486.2[M+H] ⁺ ,508.3[M+Na] ⁺ ,524.2[M+K] ⁺ .

Step 2: Under the protection of argon, slowly drop a solution of 211.4 mL (2.0 mol) of allyl chloroformate in DME 500 mL to compound VI ₁ 242.8 g (0.5 mol), 100.0 g (2.5 mol) of sodium hydroxide and 1000 mL of anhydrous DME In the mixed liquid, rapid mechanical stirring is required during the process, and the internal temperature is controlled at -5 ~ 0°C, and it takes about 3.0 hours to complete the dropwise addition. The reaction system was slowly raised to room temperature and continued to stir for 4.0 h, and TLC detected that the reaction was complete.

Filter with suction, and concentrate the mother liquor under reduced pressure. The residue was stirred and dispersed with 600 mL of ethyl acetate and 400 mL of cold water in turn, and the layers were separated after standing. The organic layer was separated, the aqueous layer was extracted with ethyl acetate (300 mL×2), the organic layers were combined, washed with saturated brine (500 mL×2), and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated to dryness under reduced pressure, and then fully dried under reduced pressure to obtain 297.0 g of off-white solid (V ₁ ). The crude product was recrystallized from a mixed solvent of ethyl acetate and petroleum ether to obtain 169.6 g of a white solid, yield 73.1%, mp 155-158°C.

¹ H NMR(d ₆ -DMSO)δ3.35(m,2H,5'-CH ₂ ),4.25(q,1H,4'-CH),4.48(t,2H,CH ₂ -CH-CH ₂ ) ,4.60(t,4H,CH ₂ -CH-CH ₂ ),5.21(m,1H,2'-CH),5.19～5.37(m,6H,CH ₂ -CH-CH ₂ ),5.44(m,1H ,3'-CH),5.80(m,3H,CHCH ₂ ),6.23(d,1H,1'-CH),6.93(d,1H,J=7.5Hz,5-CH),7.30(m,15H ,Ph ₃ ),7.91(d,1H,J=7.5Hz,6-CH),10.84(s,1H,4-NH);

ESI-MS(m/z):738.3[M+H] ⁺ ,760.3[M+Na] ⁺ ,776.3[M+K] ⁺ .

Step 3: Add about 147.5 g (0.20 mol) of compound V ₁ to 500 mL of ethyl hydrogen chloride acetate solution (2.0 mol/L) under the protection of argon at 0-5°C, and stir while adding. As the reaction proceeded, a white solid was gradually precipitated out, and TLC detection showed that the reaction ended in about 2.0 h.

Suction filtration, washing with ethyl acetate, and drying under reduced pressure gave 75.4 g of white solid. Add 500 mL of ice water to the mother liquor, adjust the pH to 7 with saturated Na ₂ CO ₃ solution, stir well and let it stand still, separate the organic layer, and extract the aqueous layer with 200 mL of ethyl acetate. The organic layers were combined, washed with saturated brine (200 mL×2), and dried over anhydrous sodium sulfate. Filtrate, concentrate under reduced pressure until turbidity appears, and stir overnight, a white solid precipitates out again, is filtered with suction, and dried under reduced pressure to obtain 23.7 g. The cumulative total yield of solid (IV ₁ ) obtained twice: 89.4%, mp69～73°C.

¹ H NMR(d ₆ -DMSO)δ3.68(d,2H,5'-CH ₂ ),4.14(d,1H,4'-CH),4.50(t,2H,CH ₂ -CH-CH ₂ ) ,4.64(t,4H,CH ₂ -CH-CH ₂ ),5.21(m,1H,2'-CH),5.15～5.42(m,6H,CH ₂ -CH-CH ₂ ),5.32(s,1H ,5'-OH)5.45(m,1H,3'-CH),5.90(m,3H,CHCH ₂ ),6.23(d,1H,1'-CH),7.06(d,1H,J=7.5Hz ,5-CH),8.18(d,1H,J=7.5Hz,6-CH),10.84(s,1H,4-NH);

ESI-MS(m/z):496.2[M+H] ⁺ ,518.2[M+Na] ⁺ ,534.2[M+K] ⁺ .

Step 4: Under ice-water bath and argon protection, EDCI41.3g (0.20mol) was slowly added to compound IV _149.5g (0.10mol), Boc-protected L-valine 26.1g (0.12mol), DMAP1.2g ( 0.01mol) and anhydrous dichloromethane 300mL mixed solution, pay attention to controlling the feed rate and controlling the reaction internal temperature to be no more than 10°C. After the addition was completed, the reaction system was slowly raised to room temperature, and the reaction was continued for about 2.0 h, and the reaction was detected by TLC.

Add 300 mL of ice water, stir well, let stand to separate layers, separate the organic layer, extract the water layer with dichloromethane (150 mL×2), combine the organic layers, and successively wash with 1.0 mol/L hydrochloric acid solution (150 mL×2), saturated Wash with sodium carbonate solution (200 mL), saturated brine (200 mL), and dry over anhydrous sodium sulfate. After filtration, the filtrate was concentrated to dryness under reduced pressure and dried under reduced pressure to obtain 64.0 g of white solid (III ₁ ), yield 92.1%, mp 149～151°C.

¹ H NMR(d ₆ -DMSO)δ0.83(d,6H,(CH ₃ ) ₂ CH),1.35(s,9H,(CH ₃ ) ₃ C),1.98(t,1H,CH(CH ₃ ) ₂ ),3.86(t,1H,CH(CH ₃ ) ₂ ),4.28～4.38(d,2H,5'-CH ₂ ),4.41(d,1H,4'-CH),4.48(t,2H, CH ₂ -CH-CH ₂ ), 4.61(t,4H,CH ₂ -CH-CH ₂ ), 5.12(m,1H,2'-CH), 5.19～5.36(m,6H,CH ₂ -CH-CH ₂ ),5.42(t,1H,3'-CH),5.80(m,3H,CHCH ₂ ),6.26(d,1H,1'-CH),7.07(d,1H,J=7.5Hz,5- CH),7.15(d,1H,NH-CH),7.98(d,1H,J=7.5Hz,6-CH),10.83(s,1H,4-NH);

ESI-MS(m/z):693.1[M+H] ⁺ .

Step 5: Under argon protection, add tetrakis(triphenylphosphine) palladium 1.15g (5.0mol%) to compound III ₁ 13.89g (0.02mol), anhydrous formic acid 4.49mL (0.12 mol), n-butylamine 11.70mL (0.12mol) and anhydrous tetrahydrofuran 200mL mixed liquid. After the addition was completed, the argon gas was repeatedly replaced by reduced pressure and vacuum to remove the air in the system, and then slowly raised to room temperature for reaction. TLC detection showed that the reaction was completed after stirring for 4.0 h.

The reaction solution was concentrated under reduced pressure, the residue was stirred and dispersed with 100 mL of dichloromethane and 100 mL of cold water in turn, and the layers were separated after standing. The organic layer was separated, the aqueous layer was extracted with dichloromethane (40 mL×2), and the organic layers were combined. The product was back-extracted into the aqueous layer with 1.0 mol/L hydrochloric acid solution (80 mL×2). The aqueous layer was fully stirred with ethyl acetate (100 mL), adjusted to pH 7 with saturated sodium carbonate solution, and then separated into layers. The organic layer was separated, and the aqueous layer was extracted with 100 mL of ethyl acetate. The organic layers were combined, washed with saturated brine (200 mL×2), and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated to dryness under reduced pressure to obtain 7.20 g of off-white solid. The crude product was recrystallized from tetrahydrofuran to obtain 6.50 g of white solid (II ₁ ), yield 73.9%, mp 168-172°C.

¹ H NMR(d ₆ -DMSO)δ0.84(d,6H,(CH ₃ ) ₂ CH),1.34(s,9H,(CH ₃ ) ₃ C),1.97(m,1H,CH(CH ₃ ) ₂ ), 3.85(m,2H,5'-CH ₂ ),3,91(m,1H,2'-CH),3.94(m,1H,CH-NH),4.13(q,1H,3'- CH),4.35(q,1H,4'-CH),5.55(t,2H,2'-OH,3'-OH),5.60(d,1H,J=7.5Hz,5-CH),6.05( d,1H,1'-CH),6.98(d,2H,4-NH ₂ ),7.11(d,1H,NH-CH),7.42(d,1H,J=7.5Hz,6-CH);

¹³ C NMR(d ₆ -DMSO)δ18.78(CH ₃ -CH), 19.38(CH ₃ -CH), 28.68((CH ₃ ) ₃ -C), 30.14(CH-CH ₃ ), 59.83(CH- NH),64.72(C-5'),74.64(C-3'),77.20(C-2'),78.71(C-(CH ₃ ) ₃ ),82.37(C-4'),86.91(C- 5), 92.92(C-1'), 143.23(C-6), 155.54(C-2), 156.23(CONH), 166.08(C-4), 172.47(COO);

ESI-MS(m/z):443.3[M+H] ⁺ ,465.3[M+Na] ⁺ ,481.2[M+K] ⁺ .

Step 6: Add 22.1 g (0.05 mol) of compound II ₁ to 100 mL of ethyl hydrogen chloride acetate solution (2.0 mol/L) at 0-5°C under the protection of argon, and stir while adding. After the addition was complete, the reaction system was slowly raised to room temperature, and a white solid was gradually precipitated as the reaction progressed. The reaction was completed in about 4.0h.

Suction filtration, washing with ethyl acetate, and drying under reduced pressure gave 19.2 g of a white solid (I _1a ) with a purity of 98.65%, mp225-228°C, and a yield of 92.5%.

¹ H NMR(d ₆ -DMSO)δ0.94(q,6H,(CH ₃ ) ₂ CH)),2.16(m,1H,CH(CH ₃ ) ₂ ),3.87(s,1H,CHNH),3.97 (m,2H,5'-CH ₂ ),4.05(m,1H,2'-CH)4.31(q,1H,3'-CH),4.50(q,1H,4'-CH),5.83(s ,2H,2'-OH,3'-OH),6.01(d,1H,1'-CH),6.12(d,1H,J=7.5Hz,5-CH),7.79(d,1H,J= 7.5Hz,6-CH),8.56(s,2H,4-NH ₂ ),8.63(d,2H,NH ₂ -CH);

¹³ C NMR(d ₆ -DMSO)δ17.92(CH ₃ -CH), 17.98(CH ₃ -CH), 29.82(CH-CH ₃ ), 57.84(CH-NH), 65.44(C-5'), 74.44(C-3'), 76.41(C-2'), 83.61(C-4'), 87.67(C-5), 93.17(C-1'), 146.23(C-6), 147.07(C- 2),160.03(C-4),169.13(COO);

ESI-MS(m/z):343.3[M+H] ⁺ ,365.3[M+Na] ⁺ ,381.3[M+K] ⁺ .

Example 2: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 2 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-valine ester, I _1a )

With CDI instead of EDCI, the reaction of step 4 in Example 1 was carried out, and the yield was 88.3%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.78%. The six-step cumulative yield is 36.2%.

Example 3: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-Dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-valine ester, I _1a ) preparation method three

With DCC instead of EDCI, the reaction of step 4 in Example 1 was carried out, and the yield was 93.4%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.56%. The cumulative yield of six steps is 37.6%.

Example 4: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 4 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-valine ester, I _1a )

PdCl ₂ was used instead of Pd(PPh ₃ ) ₄ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in Step 5 in Example 1, and the yield was 70.1%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.40%. The cumulative yield of six steps is 35.2%.

Example 5: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 5 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-valine ester, I _1a )

Substituting Pd(OAc) ₂ for Pd(PPh ₃ ) ₄ , and adding ligand PPh ₃ to the reaction system, the reaction in step 5 in Example 1 was carried out, and the yield was 66.9%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.73%. The cumulative yield of six steps is 32.8%.

Example 6: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation Method 6 of 3,4-Dihydroxytetrahydrofuryl}methyl Ester Hydrochloride (Cytarabine 5'-Position L-Valine Ester, I _1a )

Pd(PPh ₃ ) ₄ was replaced by Pd ₂ (dba) ₃ ·CHCl ₃ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in Step 5 in Example 1, and the yield was 63.8%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.36%. The cumulative yield of six steps is 32.4%.

Example 7: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation Method 7 of 3,4-Dihydroxytetrahydrofuranyl}methyl Ester Hydrochloride (Cytarabine 5'-Position L-Valine Ester, I _1a )

Using Dimedone instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 1 was carried out, and the yield was 68.2%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.69%. The cumulative yield of six steps is 32.6%.

Example 8: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 8 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-valine ester, I _1a )

Using NDMBA instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 1 was carried out, and the yield was 67.2%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.47%. The cumulative yield of six steps is 31.5%.

Example 9: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 9 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-valine ester, I _1a )

Using HCOOH/Et ₂ NH instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 1 was carried out, and the yield was 66.7%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.77%. The cumulative yield of six steps is 33.9%.

Example 10: S-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation Method 10 of 3,4-Dihydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Cytarabine 5'-position L-Valine Ester, I _1a )

The reaction in Step 5 in Example 1 was carried out with HCOOH/Et ₃ N instead of HCOOH/n-BuNH ₂ , and the yield was 67.4%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1a with a purity of 98.68%. The cumulative yield of six steps is 34.2%.

Example 11: R-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 1 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position D-valine ester, I _1b )

Boc-protected D-valine was used instead of Boc-protected L-valine to carry out the reaction in step 4 in Example 1, and the yield was 92.2%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1b to obtain 10.4 g of a white solid with a purity of 99.02%, and mp 212-215°C. The cumulative yield of six steps is 35.2%.

¹ H NMR(d ₆ -DMSO)δ0.95(q,6H,(CH ₃ ) ₂ CH)),2.16(m,1H,CH(CH ₃ ) ₂ ),3.86(s,1H,CHNH),4.00 (m,2H,5'-CH ₂ ),4.07(m,1H,2'-CH),4.35(q,1H,3'-CH),4.40(q,1H,4'-CH),5.86( s,2H,2'-OH,3'-OH),6.00(d,1H,1'-CH),6.17(d,1H,J=7.8Hz,5-CH),7.79(d,1H,J =7.8Hz,6-CH),8.62(s,2H,4-NH ₂ ),8.71(d,2H,NH ₂ -CH);

¹³ C NMR(d ₆ -DMSO)δ18.02(CH ₃ -CH), 18.86(CH ₃ -CH), 29.85(CH-CH ₃ ), 57.74(CH-NH), 65.62(C-5'), 74.61(C-3'), 76.51(C-2'), 83.20(C-4'), 87.82(C-5), 93.35(C-1'), 146.40(C-6), 147.39(C- 2), 160.00(C-4), 169.22(COO);

ESI-MS(m/z):343.3[M+H] ⁺ ,365.3[M+Na] ⁺ ,381.3[M+K] ⁺ .

Example 12: R-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 2 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position D-valine ester, I _1b )

Using Boc-protected D-valine instead of Boc-protected L-valine, and DCC instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 90.6%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1b with a purity of 98.86%. The six-step cumulative yield is 34.8%.

Example 13: R-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-Dihydroxytetrahydrofuranyl} methyl ester hydrochloride (Cytarabine 5'-position D-valine ester, I _1b ) preparation method three

Using Boc-protected D-valine instead of Boc-protected L-valine, and HATU instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 88.4%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1b with a purity of 98.25%. The six-step cumulative yield is 32.2%.

Example 14: R-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 4 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position D-valine ester, I _1b )

The reaction in Step 4 in Example 1 was carried out with Boc-protected D-valine instead of Boc-protected L-valine. PdCl ₂ was used instead of Pd(PPh ₃ ) ₄ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in Step 5 of Example 1, and the yield was 69.5%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1b with a purity of 98.10%. The cumulative yield of six steps is 33.0%.

Example 15: R-2-amino-3-methylbutanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation Method 5 of 3,4-Dihydroxytetrahydrofuranyl}methyl Ester Hydrochloride (Cytarabine 5'-D-Valine Ester, I _1b )

The reaction in Step 4 in Example 1 was carried out with Boc-protected D-valine instead of Boc-protected L-valine. HCOO NH ₄ ⁺ was used instead of HCOOH/n-BuNH ₂ to carry out the reaction in Step 5 in Example 1, and the yield was 68.2%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1b with a purity of 98.68%. The cumulative yield of six steps is 34.2%.

Example 16: S-2-aminopropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-3,4-di Preparation Method 1 of Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Cytarabine 5'-Position L-Alanine Ester, I _1c )

Using Boc-protected L-alanine instead of Boc-protected L-valine, the reaction in step 4 in Example 1 was carried out, and the yield was 90.6%. According to the steps in Example 1, the rest of the reaction steps were carried out to prepare compound I _1c to obtain 8.9 g of white solid with a purity of 98.93%, and mp 203-207°C. The cumulative yield of six steps is 37.6%.

¹ H NMR(d ₆ -DMSO)δ1.39(d,3H,CH ₃ -CH),3.96(s,1H,CHNH),4.05(m,2H,5'-CH ₂ ),4.11(m,1H ,2'-CH),4.32(q,1H,3'-CH),4.43(q,1H,4'-CH),5.81(s,2H,2'-OH,3'-OH),6.00( d,1H,1'-CH),6.13(d,1H,J=7.6Hz,5-CH),7.77(d,1H,J=7.6Hz,6-CH),8.55(s,2H,4- NH ₂ ),8.60(d,2H,NH ₂ -CH);

¹³ C NMR(d ₆ -DMSO)δ16.15(CH ₃ -CH), 48.38(CH-CH ₃ ), 65.50(C-5'), 74.66(C-3'), 76.44(C-2') ,83.18(C-4'),87.55(C-5),93.34(C-1'),146.26(C-6),147.58(C-2),160.15(C-4),170.36(COO);

ESI-MS(m/z):315.3[M+H] ⁺ ,337.2[M+Na] ⁺ ,353.2[M+K] ⁺ .

Example 17: S-2-aminopropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-3,4-di Hydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-alanine ester, I _1c ) preparation method two

Using Boc-protected L-alanine instead of Boc-protected L-valine, and CDI instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 85.3%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1c with a purity of 98.59%. The cumulative yield of six steps is 36.4%.

Example 18: S-2-aminopropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-3,4-di Preparation Method Three of Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Cytarabine 5'-Position L-Alanine Ester, I _1c )

Using Boc-protected L-alanine instead of Boc-protected L-valine, and HBTU instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 89.0%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1c with a purity of 98.23%. The cumulative yield of six steps is 31.6%.

Example 19: S-2-aminopropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-3,4-di Preparation method four of hydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-alanine ester, I _1c )

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-alanine instead of Boc-protected L-valine. Pd(OAc) ₂ was used instead of Pd(PPh ₃ ) ₄ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in Step 5 of Example 1, and the yield was 68.3%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1c with a purity of 98.55%. The cumulative yield of six steps is 32.9%.

Example 20: S-2-aminopropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-3,4-di Preparation Method 5 of Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Cytarabine 5'-Position L-Alanine Ester, I _1c )

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-alanine instead of Boc-protected L-valine. And using (Et ₂ NH ₂ ⁺ ) ₂ CO ₃ ² instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 1 was carried out, and the yield was 69.3%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1c with a purity of 98.22%. The six-step cumulative yield is 34.1%.

Example 21: S-2-amino-4-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 1 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-leucine ester, I _1d )

Using Boc-protected L-leucine instead of Boc-protected L-valine, the reaction in Step 4 in Example 1 was carried out, and the yield was 92.3%. Compound I _1d was prepared according to the steps in Example 1 to obtain 9.7 g of white solid with a purity of 98.52% and mp 203-207°C. The cumulative yield of six steps is 35.4%.

¹ H NMR(d ₆ -DMSO)δ0.86(q,6H,(CH ₃ ) ₂ CH)),1.64(t,2H,CH ₂ ),1,75(m,1H,CH(CH ₃ ) ₂ ),3.92(s,1H,CHNH),4.00(m,2H,5'-CH ₂ ),4.06(m,1H,2'-CH),4.31(q,1H,3'-CH),4.43( q,1H,4'-CH),5.86(s,2H,2'-OH,3'-OH),5.99(d,1H,1'-CH),6.17(d,1H,J=7.8Hz, 5-CH),7.79(d,1H,J=7.8Hz,6-CH),8.66(s,2H,4-NH ₂ ),8.75(d,2H,NH ₂ -CH);

¹³ C NMR(d ₆ -DMSO)δ22.44(CH ₃ -CH ₂ ), 22.67(CH ₃ -CH ₂ ), 24.22(CH-(CH ₃ ) ₂ ), 40.24(CH ₂ -CHNH ₂ ), 51.10 (CH-NH),65.52(C-5'),74.57(C-3'),76.48(C-2'),83.36(C-4'),87.74(C-5),93.24(C-1 '), 146.29(C-6), 147.21(C-2), 160.03(C-4), 170.19(COO);

ESI-MS(m/z):357.3[M+H] ⁺ ,379.2[M+Na] ⁺ ,395.2[M+K] ⁺ .

Example 22: S-2-amino-4-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 2 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-leucine ester, I _1d )

Using Boc-protected L-leucine instead of Boc-protected L-valine, and HATU instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 87.6%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1d with a purity of 98.56%. The six-step cumulative yield is 34.1%.

Example 23: S-2-amino-4-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-Dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-leucine ester, I _1d ) preparation method three

Using Boc-protected L-leucine instead of Boc-protected L-valine, and HOAt instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 85.6%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1d with a purity of 98.78%. The six-step cumulative yield is 31.9%.

Example 24: S-2-amino-4-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 4 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-leucine ester, I _1d )

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-leucine instead of Boc-protected L-valine. Pd(PPh ₃ ) ₄ was replaced by Pd ₂ (dba) ₃ ·CHCl ₃ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in step 5 in Example 1, and the yield was 69.1%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1d with a purity of 98.63%. The cumulative yield of six steps is 32.6%.

Example 25: S-2-amino-4-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 5 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-leucine ester, I _1d )

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-leucine instead of Boc-protected L-valine. And using Et ₂ NH ₂ ⁺ HCO ₃ instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 1 was carried out, and the yield was 66.3%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1d with a purity of 98.67%. The cumulative yield of six steps is 34.9%.

Example 26: S-2-amino-3-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 1 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-isoleucine ester, I _1e )

Using Boc-protected L-isoleucine instead of Boc-protected L-valine, the reaction in Step 4 in Example 1 was carried out, and the yield was 90.8%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1e to obtain 8.8 g of a white solid with a purity of 99.01%, and mp 216-218°C. The cumulative yield of six steps is 34.3%.

¹ H NMR(d ₆ -DMSO)δ0.87(q,6H,CH ₃ CH ₂ ,CH ₃ CH),1.25(t,1H,CH ₂ CH ₃ ),1.43(t,1H,CH ₂ CH ₃ ) ,1.92(m,1H,CH ₃ CH),3.91(s,1H,CHNH),4.00(m,2H,5'-CH ₂ ),4.07(m,1H,2'-CH),4.29(q, 1H,3'-CH),4.51(q,1H,4'-CH),5.80(s,1H,3'-OH),5.84(s,1H,2'-OH),6.01(d,1H, 1'-CH),6.10(d,1H,J=7.8Hz,5-CH),7.75(d,1H,J=7.8Hz,6-CH),8.60(s,2H,4-NH ₂ ), 8.60(s,2H,NH ₂ -CH);

¹³ C NMR(d ₆ -DMSO)δ12.00(CH ₃ -CH ₂ ), 14.67(CH ₃ -CH), 25.84(CH ₂ -CH ₃ ), 36.38(CH-CH ₃ ), 56.54(CH-NH ),65.42(C-5'),74.45(C-3'),76.45(C-2'),83.62(C-4'),87.90(C-5),93.15(C-1'),146.15 (C-6), 147.14(C-2), 160.06(C-4), 169.02(COO);

ESI-MS(m/z):357.3[M+H] ⁺ ,379.2[M+Na] ⁺ ,395.2[M+K] ⁺ .

Example 27: S-2-amino-3-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 2 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-isoleucine ester, I _1e )

Using Boc-protected L-isoleucine instead of Boc-protected L-valine, and HBTU instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 86.1%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1e with a purity of 98.91%. The cumulative yield of six steps is 33.5%.

Example 28: S-2-amino-3-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-Dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-isoleucine ester, I _1e ) preparation method three

Using Boc-protected L-isoleucine instead of Boc-protected L-valine, and HOBt instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 87.6%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1e with a purity of 98.46%. The cumulative yield of six steps is 32.9%.

Example 29: S-2-amino-3-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 4 of 3,4-dihydroxytetrahydrofuryl} methyl ester hydrochloride (cytarabine 5'-position L-isoleucine ester, I _1e )

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-isoleucine instead of Boc-protected L-valine. Dimedone was used instead of HCOOH/n-BuNH ₂ to carry out the reaction in Step 5 in Example 1, and the yield was 65.7%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1e with a purity of 98.38%. The six-step cumulative yield is 30.9%.

Example 30: S-2-amino-3-methylpentanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 5 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (Cytarabine 5'-position L-isoleucine ester, I _1e )

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-isoleucine instead of Boc-protected L-valine. And HCOOH/Et ₂ NH was used instead of HCOOH/n-BuNH ₂ to carry out the reaction in Step 5 in Example 1, and the yield was 70.1%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1e with a purity of 98.28%. The cumulative yield of six steps is 32.6%.

Example 31: S-2-amino-3-phenylpropanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 1 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-phenylalanine ester, I _1f )

Using Boc-protected L-phenylpropionic acid instead of Boc-protected L-valine, the reaction in Step 4 in Example 1 was carried out, and the yield was 92.3%. According to the steps in Example 1, the rest of the reaction steps were carried out to prepare compound I _1f to obtain 8.2 g of white solid with a purity of 98.67%, and mp 200-203°C. The cumulative yield of six steps is 38.7%.

¹ H NMR(d ₆ -DMSO)δ3.13(q,2H,CH ₂ Ph),3.92(s,1H,CHNH),3.99(m,2H,5'-CH ₂ ),4.14(m,1H, 2'-CH), 4.28(q, 1H, 3'-CH), 4.31(q, 1H, 4'-CH), 5.82(s, 2H, 3'-OH, 2'-OH), 5.99(d ,1H,1'-CH),6.14(d,1H,J=7.8Hz,5-CH),7.26(m,5H,Ph),7.74(d,1H,J=7.8Hz,6-CH), 8.68(s,2H,4-NH ₂ ),8.68(s,2H,NH ₂ -CH);

¹³ C NMR(d ₆ -DMSO)δ36.22(CH-Ph),53.85(CH-NH),65.58(C-5'),74.59(C-3'),76.44(C-2'),83.22 (C-4'),87.70(C-5),93.30(C-1'),127.71,129.03,129.96,135.20(Ph-CH),146.31(C-6),147.24(C-2),160.02 (C-4),169.22(COO);

ESI-MS(m/z):391.3[M+H] ⁺ ,413.3[M+Na] ⁺ .

Example 32: S-2-amino-3-phenylpropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 2 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-phenylalanine ester, I _1f )

Using Boc-protected L-phenylalanine instead of Boc-protected L-valine, and HATU instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 86.9%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _1f with a purity of 98.61%. The cumulative yield of six steps is 32.5%.

Example 33: S-2-amino-3-phenylpropanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-Dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-phenylalanine ester, I _1f ) preparation method three

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-phenylalanine instead of Boc-protected L-valine. Et ₃ N/HCOOH was used instead of HCOOH/n-BuNH ₂ to carry out the reaction in Step 5 in Example 1, and the yield was 68.2%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1f with a purity of 98.53%. The cumulative yield of six steps is 34.0%.

Example 34: S-2-amino-3-phenylpropanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method four of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position L-phenylalanine ester, I _1f )

The reaction in Step 4 in Example 1 was carried out with Boc-protected L-phenylalanine instead of Boc-protected L-valine. And NDMBA was used instead of HCOOH/n-BuNH ₂ to carry out the reaction in Step 5 in Example 1, and the yield was 64.7%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _1f with a purity of 98.47%. The cumulative yield of six steps is 34.7%.

Example 35: R-2-amino-3-phenylpropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 1 of 3,4-dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position D-phenylalanine ester, I _1g )

Using Boc-protected D-phenylalanine instead of Boc-protected L-valine, the reaction in step 4 in Example 1 was carried out, and the yield was 91.2%. According to the steps in Example 1, the remaining steps were carried out to prepare 1 g of compound I, and 8.2 _g of white solid was obtained, with a purity of 98.49%, and mp 209-211°C. The cumulative yield of six steps is 37.6%.

¹ H NMR(d ₆ -DMSO)δ3.14(m,2H,CH ₂ Ph),3.90(s,1H,CHNH),3.95(m,2H,5'-CH ₂ ),4.15(m,1H, 2'-CH),4.22(q,1H,3'-CH),4.35(q,1H,4'-CH),5.74(s,1H,3'-OH),5.80(s,1H,2' -OH), 5.98(d,1H,1'-CH),6.09(d,1H,J=7.8Hz,5-CH),7.25(m,5H,Ph),7.72(d,1H,J=7.8 Hz,6-CH),8.56(s,2H,4-NH ₂ ),8.72(s,2H,NH ₂ -CH);

¹³ C NMR(d ₆ -DMSO)δ36.34(CH-Ph),53.81(CH-NH),65.63(C-5'),74.59(C-3'),76.49(C-2'),82.94 (C-4'),87.65(C-5),93.36(C-1'),127.74,129.07,129.90,135.14(Ph-CH),146.09(C-6),148.31(C-2),160.75 (C-4),169.32(COO);

ESI-MS(m/z):391.3[M+H] ⁺ ,413.3[M+Na] ⁺ ,429.2[M+K] ⁺ .

Example 36: R-2-amino-3-phenylpropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-dihydroxytetrahydrofuryl} methyl ester hydrochloride (cytarabine 5'-position D-phenylalanine ester, I _1g ) preparation method two

Boc-protected D-phenylalanine was used instead of Boc-protected L-valine, and HOAt was used instead of EDCI to carry out the reaction in step 4 in Example 1, and the yield was 87.1%. According to the steps in Example 1, the remaining steps were carried out to prepare Compound I _1g with a purity of 98.36%. The cumulative yield of six steps is 34.6%.

Example 37: R-2-amino-3-phenylpropionic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-Dihydroxytetrahydrofuryl} methyl ester hydrochloride (cytarabine 5'-position D-phenylalanine ester, I _1g ) preparation method three

The reaction in Step 4 in Example 1 was carried out with Boc-protected D-phenylalanine instead of Boc-protected L-valine. PdCl ₂ was used instead of Pd(PPh ₃ ) ₄ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in Step 5 in Example 1, and the yield was 64.7%. According to the steps in Example 1, the remaining steps were carried out to prepare Compound I _1g with a purity of 98.69%. The six-step cumulative yield is 33.6%.

Example 38: R-2-amino-3-phenylpropanoic acid 2-{(2R,3S,4S,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 3,4-Dihydroxytetrahydrofuranyl} methyl ester hydrochloride (cytarabine 5'-position D-phenylalanine ester, I _1g ) preparation method four

The reaction in Step 4 in Example 1 was carried out with Boc-protected D-phenylalanine instead of Boc-protected L-valine. And HCOOH/Et ₂ NH was used instead of HCOOH/n-BuNH ₂ to carry out the reaction in Step 5 in Example 1, and the yield was 69.9%. According to the steps in Example 1, the remaining steps were carried out to prepare Compound I _1g with a purity of 98.62%. The cumulative yield of six steps is 34.7%.

Example 39: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 1 of 4-difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (5'-position L-valine ester of gemcitabine, I _2a )

Step 1: Under argon protection and cold water cooling, slowly add 10.70 g (38.37 mmol) of trityl chloride to a mixture of 10.00 g (33.37 mmol) of gemcitabine hydrochloride (VII ₂ ) and 100 mL of anhydrous pyridine. Stir the reaction system and control the feeding speed to gradually disperse or dissolve the added materials in the system. After the addition, continue to stir for 2h, then slowly warm up to 30°C and continue to react for 20h, and TLC detects that the reaction is complete.

Concentrate under reduced pressure to recover as much pyridine as possible in the reaction system, and then add 20 mL of absolute ethanol to the residue to fully disperse the content. The mixture was slowly poured into 500 mL of ice water, stirred rapidly to thaw, and a white solid was precipitated.

Suction filtration, washing with water, and drying gave 16.50 g of light yellow crude product. The crude product was recrystallized with 40 mL of ethyl acetate, filtered with suction, and the filtrate gradually precipitated a white solid after cooling. Stand overnight, filter with suction, and dry to obtain 15.39 g of white solid (VI ₂ ), with a yield of 91.2%. mp267～269°C

¹ H NMR(d ₆ -DMSO)δ3.28(d,2H,5'-CH ₂ ),3.98(m,1H,3'-CH),4.28(q,1H,4'-CH),5.63( d,1H,J=7.5Hz,5-CH),6.17(s,1H,3'-OH),6.33(d,1H,1'-H),7.21(s,2H,4-NH ₂ ), 7.37(m,15H,Ph ₃ ),7.62(d,1H,J=7.5Hz,6-CH);

ESI-MS(m/z):506.2[M+H] ⁺ ,528.2[M+Na] ⁺ ,544.2[M+K] ⁺ .

Step 2: Under argon protection, a solution of 3.91 mL (37.86 mmol) of allyl chloroformate in 20 mL of dichloromethane was slowly added dropwise to 8.70 g (17.21 mmol) of compound VI ₂ , 2.38 g (60.23 mmol) of sodium hydroxide and Anhydrous dichloromethane 50mL mixed liquid, need to stir rapidly during the process, and control the internal temperature at -5 ~ 0 ° C, it takes about 0.5h to complete the dropwise addition. The reaction system was slowly raised to room temperature and continued to stir for 4.0 h, and TLC detected that the reaction was complete.

Add 80 mL of ice water, stir well, let stand to separate layers, separate the organic layer, extract the water layer with dichloromethane (40 mL×2), combine the organic layers, wash with saturated brine (150 mL×2), anhydrous sodium sulfate dry. After filtration, the filtrate was concentrated to dryness under reduced pressure, and then fully dried under reduced pressure to obtain 11.32 g of light yellow waxy solid. The crude product was recrystallized from a mixed solvent of ethyl acetate and petroleum ether to obtain 10.35 g of a white solid (V ₂ ), with a yield of 89.3%. mp140～142°C.

¹ H NMR(d ₆ -DMSO)δ3.42(m,2H,5'-CH ₂ ),4.40(q,1H,4'-CH),4.67(m,4H,CH ₂ -CH-CH ₂ ) ,5.23～5.38(m,4H,CH ₂ -CH-CH ₂ ),5.42(m,1H,3'-CH),5.92(m,2H,CHCH ₂ ),6.30(m,1H,1'-CH ),7.04(d,1H,J=7.6Hz,5-CH),7.31(m,15H,Ph ₃ ),8.01(d,1H,J=7.6Hz,6-CH),11.04(s,1H, 4-NH);

ESI-MS(m/z):674.4[M+H] ⁺ ,696.4[M+Na] ⁺ ,712.3[M+K] ⁺ ,672.2[MH] ^- .

Step 3: Add 6.76 g (0.01 mol) of compound V ₂ to 50 mL of ethyl hydrogen chloride acetate solution (2.0 mol/L) under the protection of argon at 0-5°C, and stir while adding. As the reaction proceeded, a white solid was gradually precipitated, and TLC detected that the reaction was over in about 2.0 h.

Suction filtration, washing with ethyl acetate, and drying under reduced pressure gave 2.95 g of white solid. Add 20 mL of ice water to the mother liquor, adjust the pH to 7 with saturated Na ₂ CO ₃ solution, stir well and let it stand still, separate the organic layer, and extract the aqueous layer with 50 mL of ethyl acetate. The organic layers were combined, washed with saturated brine (100 mL×2), and dried over anhydrous sodium sulfate. Filtrate, concentrate under reduced pressure until turbidity appears, and stir overnight, a white solid precipitates again, is filtered with suction, and dried under reduced pressure to obtain 0.88 g. The cumulative total yield of solid (IV ₂ ) obtained twice: 88.6%. mp155～156°C.

¹ H NMR(d ₆ -DMSO)δ3.70(m,2H,5'-CH ₂ ),4.24(q,1H,4'-CH),4.62(m,4H,CH ₂ -CH-CH ₂ ) ,5.19(s,1H,5'-OH),5.27(m,4H,CH ₂ -CH-CH ₂ ),5.36(m,1H,3'-CH),5.91(m,2H,CHCH ₂ ), 6.26(t,1H,1'-CH),7.08(d,1H,J=7.6Hz,5-CH),8.12(d,1H,J=7.6Hz,6-CH),10.96(s,1H, 4-NH);

ESI-MS(m/z):432.1[M+H] ⁺ ,454.1[M+Na] ⁺ ,430.0[MH] ^- .

Step 4: Under ice-water bath and argon protection, slowly add 3.56g (18.55mmol) of EDCI to 4.00g (9.27mmol) of compound IV ₂ , 2.22g (10.2mmol) of Boc-protected L-valine, 0.12g of DMAP ( 1.00mmol) and anhydrous dichloromethane 40mL mixed solution, pay attention to controlling the feed rate and controlling the reaction internal temperature to be no more than 10°C. After the addition was completed, the reaction system was slowly raised to room temperature, and the reaction was continued for about 2.0 h, and the reaction was detected by TLC.

Add 40 mL of ice water, stir well, let stand to separate layers, separate the organic layer, extract the water layer with dichloromethane (15 mL×2), combine the organic layers, and successively wash with 1.0 mol/L hydrochloric acid solution (50 mL×2), saturated Wash with sodium carbonate solution (50 mL), saturated brine (50 mL), and dry over anhydrous sodium sulfate. After filtration, the filtrate was concentrated to dryness under reduced pressure and dried under reduced pressure to obtain 5.17 g of white solid (III ₂ ), with a yield of 88.4%. mp136～138°C.

¹ H NMR(d ₆ -DMSO)δ0.83(d,6H,(CH ₃ ) ₂ CH),1.33(s,9H,(CH ₃ ) ₃ C),1.96(t,1H,CH(CH ₃ ) ₂ ),3.82(t,1H,CH-NH),4.34(q,1H,4'-CH),4.50(d,2H,5'-CH ₂ ),4.63(q,4H,CH ₂ -CH- CH ₂ ),5.25(m,4H,CH ₂ -CH-CH ₂ ),5.36(t,1H,3'-CH),5.90(m,2H,CHCH ₂ ),6.31(t,1H,1'- CH),7.14(d,1H,NH-CH),7.25(d,1H,J=8.0Hz,5-CH),8.00(d,1H,J=8.0Hz,6-CH),11.00(s, 1H,4-NH);

ESI-MS(m/z):631.2[M+H] ⁺ ,653.2[M+Na] ⁺ ,669.2[M+K] ⁺ .

Step 5: Under argon protection, add tetrakis(triphenylphosphine) palladium 0.28g (5.0mol%) to compound III ₂ 3.00g (4.76mmol), anhydrous formic acid 1.07mL (28.54 mmol), n-butylamine 2.78mL (28.54mmol) and anhydrous tetrahydrofuran 60mL mixed solution. After the addition was completed, the argon gas was repeatedly replaced by reduced pressure and vacuum to remove the air in the system, and then slowly raised to room temperature for reaction. TLC detection showed that the reaction was completed after 6.0 h of stirring reaction.

The reaction solution was concentrated under reduced pressure, and the residue was stirred and dispersed with 40 mL of dichloromethane and 50 mL of cold water in turn, and the layers were separated after standing. The organic layer was separated, the aqueous layer was extracted with dichloromethane (30 mL×2), and the organic layers were combined. The product was back-extracted into the aqueous layer with 1.0 mol/L hydrochloric acid solution (50 mL×2). The aqueous layer was fully stirred with ethyl acetate (80 mL), adjusted to pH 7 with saturated sodium carbonate solution, and then separated into layers. The organic layer was separated, and the aqueous layer was extracted with 80 mL of ethyl acetate. The organic layers were combined, washed with saturated brine (150 mL×2), and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated to dryness under reduced pressure to obtain 1.68 g of off-white solid. The crude product was recrystallized from tetrahydrofuran to obtain 1.55 g of white solid (II ₂ ), with a yield of 70.4%. mp151～153°C.

¹ H NMR(d ₆ -DMSO)δδ0.83(q,6H,(CH ₃ ) ₂ CH),1.33(s,9H,(CH ₃ ) ₃ C),1.96(m,1H,CH(CH ₃ ) ₂ ),3.82(t,1H,CH-NH),3.98(m,1H,3'-CH),4.20(m,1H,4'-CH),4.31(q,2H,5'-CH ₂ ) ,5.76(d,1H,J=7.6Hz,5-CH),6.13(t,1H,1'-CH),6.42(d,1H,3'-OH),7.24(d,1H,NH-CH ),7.38(d,2H,4-NH ₂ ),7.47(d,1H,J=7.6Hz,6-CH);

ESI-MS(m/z):463.2[M+H] ⁺ ,485.1[M+Na] ⁺ ,501.1[M+K] ⁺ .

Step 6: Add 1.55 g (3.35 mmol) of compound II ₂ to 20 mL of ethyl hydrogen chloride acetate solution (2.0 mol/L) at 0-5°C under the protection of argon, and stir while adding. After the addition was complete, the reaction system was slowly raised to room temperature, and a white solid was gradually precipitated as the reaction progressed. The reaction was completed in about 4.0h.

Suction filtration, washing with ethyl acetate, and drying under reduced pressure gave 1.34 g of white solid (I _2a ), with a purity of 98.75%, and mp 230-232°C. The yield is 91.8%.

¹ H NMR(d ₆ -DMSO)δ0.93(q,6H,(CH ₃ ) ₂ CH)),2.15(m,1H,CH(CH ₃ ) ₂ ),3.91(m,1H,CHNH ₂ ), 4.13(m,1H,3'-CH),4.27(q,1H,4'-CH),4.46(q,2H,5'- _CH2 ),6.12(t,1H,1'-CH),6.19 (d,1H,J=7.6Hz,5-CH),7.88(d,1H,J=7.6Hz,6-CH),8.60(s,2H,4-NH ₂ ),8.69(s,2H,NH ₂ -CH);

ESI-MS(m/z):363.1[M+H] ⁺ ,385.1[M+Na] ⁺ ,401.1[M+K] ⁺ .

Example 40: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 2 of 4-difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (5'-position L-valine ester of gemcitabine, I _2a )

The reaction of Step 4 in Example 39 was carried out with CDI instead of EDCI, and the yield was 89.6%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.90%. The cumulative yield of six steps is 32.1%.

Example 41: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, 4-Difluoro-3-hydroxytetrahydrofuryl} methyl ester hydrochloride (5'-position L-valine ester of gemcitabine, I _2a ) preparation method three

The reaction of Step 4 in Example 39 was carried out with DCC instead of EDCI, and the yield was 91.3%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.60%. The cumulative yield of six steps is 31.5%.

Example 42: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 4-difluoro-3-hydroxytetrahydrofuryl}methyl ester hydrochloride (5'-position L-valine ester of gemcitabine, I _2a )

PdCl ₂ was used instead of Pd(PPh ₃ ) ₄ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in Step 5 in Example 39, and the yield was 67.2%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.42%. The cumulative yield of six steps is 31.0%.

Example 43: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method 5 of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-Position L-Valine Ester, I _2a )

Substituting Pd(OAc) ₂ for Pd(PPh ₃ ) ₄ , and adding ligand PPh ₃ to the reaction system, the reaction in Step 5 in Example 39 was carried out, and the yield was 66.8%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.51%. The cumulative yield of six steps is 32.9%.

Example 44: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method of 4-difluoro-3-hydroxytetrahydrofuryl} methyl ester hydrochloride (5'-position L-valine ester of gemcitabine, I _2a ) six

Pd(PPh ₃ ) ₄ was replaced by Pd ₂ (dba) ₃ ·CHCl ₃ , and ligand PPh ₃ was added to the reaction system to carry out the reaction in Step 5 in Example 39, with a yield of 62.8%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.28%. The cumulative yield of six steps is 31.8%.

Example 45: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method 7 of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-Position L-Valine Ester, I _2a )

Using Dimedone instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 39 was carried out, and the yield was 64.9%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.44%. The cumulative yield of six steps is 32.8%.

Example 46: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 8 of 4-difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (5'-position L-valine ester of gemcitabine, I _2a )

The reaction in Step 5 in Example 39 was carried out with NDMBA instead of HCOOH/n-BuNH ₂ , and the yield was 65.9%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.34%. The cumulative yield of six steps is 33.1%.

Example 47: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method 9 of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-Position L-Valine Ester, I _2a )

The reaction in Step 5 in Example 39 was carried out with HCOOH/Et ₂ NH instead of HCOOH/n-BuNH ₂ , and the yield was 68.6%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.72%. The cumulative yield of six steps is 33.5%.

Example 48: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method 10 of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-Position L-Valine Ester, I _2a )

Using HCOOH/Et ₃ N instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 39 was carried out, and the yield was 69.1%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2a with a purity of 98.92%. The six-step cumulative yield is 32.2%.

Example 49: R-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 1 of 4-difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (5'-position D-valine ester of gemcitabine, I _2b )

Boc-protected D-valine was used instead of Boc-protected L-valine to carry out the reaction in step 4 in Example 39, and the yield was 92.0%. According to the procedure in Example 39, the rest of the reaction steps were carried out to prepare compound I _2b to obtain 1.52 g of a white solid with a purity of 98.71%, and mp 226-228°C. The cumulative yield of six steps is 33.2%.

¹ H NMR(d ₆ -DMSO)δ0.94(d,6H,(CH ₃ ) ₂ CH)),2.16(m,1H,CH(CH ₃ ) ₂ ),3.92(s,1H,CHNH),4.10 (m,1H,3'-CH),4.32(q,1H,4'-CH),4.47(m,2H,5'-CH ₂ ),6.13(t,1H,1'-CH),6.18( d,1H,J=7.8Hz,5-CH),7.90(d,1H,J=7.8Hz,6-CH),8.58(s,2H,4-NH ₂ ),8.73(d,2H,NH ₂ -CH);

ESI-MS(m/z):363.1[M+H] ⁺ ,385.1[M+Na] ⁺ .

Example 50: R-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method 2 of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-D-Valine Ester, I _2b )

Boc-protected D-valine was used instead of Boc-protected L-valine, and DCC was used instead of EDCI to carry out the reaction in step 4 in Example 39, and the yield was 92.2%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2b with a purity of 98.65%. The cumulative yield of six steps is 35.2%.

Example 51: R-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, 4-Difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (gemcitabine 5'-position D-valine ester, I _2b ) preparation method three

The reaction in Step 4 in Example 39 was carried out with Boc-protected D-valine instead of Boc-protected L-valine. PdCl ₂ was used instead of Pd(PPh ₃ ) ₄ , and ligand PPh ₃ was added to the reaction system at the same time, and the reaction in Step 5 in Example 39 was carried out, and the yield was 66.9%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2b with a purity of 98.37%. The cumulative yield of six steps is 34.0%.

Example 52: R-2-amino-3-methylbutanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, 4-Difluoro-3-hydroxytetrahydrofuryl} methyl ester hydrochloride (gemcitabine 5'-position D-valine ester, I _2b ) preparation method four

The reaction in Step 4 in Example 39 was carried out with Boc-protected D-valine instead of Boc-protected L-valine. And using HCOO NH ₄ ⁺ instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 39 was carried out, and the yield was 62.1%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2b with a purity of 98.62%. The cumulative yield of six steps is 32.4%.

Example 53: S-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- 3-Hydroxytetrahydrofuranyl} methyl ester hydrochloride (gemcitabine 5'-position L-alanine ester, I _2c ) preparation method one

Using Boc-protected L-alanine instead of Boc-protected L-valine, the reaction in Step 4 in Example 39 was carried out, and the yield was 90.6%. According to the procedure in Example 39, the remaining steps were carried out to prepare compound I _2c to obtain 1.15 g of a white solid with a purity of 98.50% and mp 237-239°C. The cumulative yield of six steps is 32.1%.

¹ H NMR (d ₆ -DMSO)δ1.38(d,3H,CH ₃ -CH),3.86(q,1H,CHNH),4.10(m,1H,3'-CH),4.32(q,1H, 4'-CH), 4.47(m, 2H, 5'-CH ₂ ), 6.13(t, 1H, 1'-CH), 6.18(d, 1H, J=7.6Hz, 5-CH), 7.90(d ,1H,J=7.6Hz,6-CH),8.58(s,2H,4-NH ₂ ),8.73(d,2H,NH ₂ -CH);

ESI-MS(m/z):335.0[M+H] ⁺ ,357.0[M+Na] ⁺ ,372.9[M+K] ⁺ .

Example 54: S-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- Preparation Method 2 of 3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-position L-alanine Ester, I _2c )

Using Boc-protected L-alanine instead of Boc-protected L-valine, and CDI instead of EDCI, the reaction in step 4 in Example 39 was carried out, and the yield was 89.5%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2c with a purity of 98.85%. The cumulative yield of six steps is 36.7%.

Example 55: S-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- Preparation Method Three of 3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-L-Alanine Ester, I _2c )

The reaction in Step 4 in Example 39 was carried out with Boc-protected L-alanine instead of Boc-protected L-valine. Pd(OAc) ₂ was used instead of Pd(PPh ₃ ) ₄ , and ligand PPh ₃ was added to the reaction system at the same time, and the reaction in step 5 in Example 39 was carried out, and the yield was 68.4%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2c with a purity of 98.70%. The cumulative yield of six steps is 34.9%.

Example 56: S-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- Preparation Method 4 of 3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-Position L-Alanine Ester, I _2c )

The reaction in Step 4 in Example 39 was carried out with Boc-protected L-alanine instead of Boc-protected L-valine. And using Et ₂ NH ₂ ⁺ HCO ₃ instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 39 was carried out, and the yield was 68.1%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2c with a purity of 98.67%. The six-step cumulative yield is 33.3%.

Example 57: R-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- Preparation Method 1 of 3-Hydroxytetrahydrofuranyl}methyl Ester Hydrochloride (Gemcitabine 5'-Position D-Alanine Ester, I _2d )

Boc-protected D-alanine was used instead of Boc-protected L-valine to carry out the reaction in step 4 in Example 39, and the yield was 90.8%. Compound I _2d was prepared by following the steps in Example 39 to obtain 1.22 g of a white solid with a purity of 98.42% and mp 241-243°C. The cumulative yield of six steps is 33.6%.

¹ H NMR(d ₆ -DMSO)δ1.39(d,3H,CH ₃ -CH),3.98(q,1H,CHNH ₂ ),4.12(m,1H,3'-CH),4.34(q,1H ,4'-CH),4.46(m,2H,5'-CH ₂ ),6.11(t,1H,1'-CH),6.20(d,1H,J=7.8Hz,5-CH),7.99( d,1H,J=7.8Hz,6-CH),8.59(s,2H,4-NH ₂ ),8.77(s,2H,NH ₂ -CH);

ESI-MS(m/z):335.1[M+H] ⁺ ,357.1[M+Na] ⁺ ,332.9[MH] ^- ,378.9[M+HCOO] ^- .

Example 58: R-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- Preparation Method 2 of 3-Hydroxytetrahydrofuranyl}methyl Ester Hydrochloride (Gemcitabine 5'-Position D-Alanine Ester, I _2d )

Using Boc-protected D-alanine instead of Boc-protected L-valine, and HATU instead of EDCI, the reaction in step 4 in Example 39 was carried out, and the yield was 85.6%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2d with a purity of 98.69%. The cumulative yield of six steps is 33.9%.

Example 59: R-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- Preparation Method 3 of 3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (D-Alanine Ester at 5'-position of Gemcitabine, I _2d )

The reaction in Step 4 in Example 39 was carried out with Boc-protected D-alanine instead of Boc-protected L-valine. Pd(PPh ₃ ) ₄ was replaced by Pd ₂ (dba) ₃ ·CHCl ₃ , and ligand PPh ₃ was added to the reaction system at the same time, and the reaction in step 5 in Example 39 was carried out, and the yield was 67.2%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2d with a purity of 98.64%. The cumulative yield of six steps is 33.7%.

Example 60: R-2-Alanine 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro- 3-Hydroxytetrahydrofuranyl} methyl ester hydrochloride (gemcitabine 5'-position D-alanine ester, I _2d ) preparation method four

The reaction in Step 4 in Example 39 was carried out with Boc-protected D-alanine instead of Boc-protected L-valine. And using (Et ₂ NH ₂ ⁺ ) ₂ CO ₃ ² instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 39 was carried out, and the yield was 62.4%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2d with a purity of 98.51%. The cumulative yield of six steps is 32.0%.

Example 61: S-2-amino-4-methylpentanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 1 of 4-difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (5'-position L-leucine ester of gemcitabine, I _2e )

Using Boc-protected L-leucine instead of Boc-protected L-valine, the reaction in Step 4 in Example 39 was carried out, and the yield was 89.3%. According to the procedure in Example 39, the remaining steps were carried out to prepare compound I _2e to obtain 1.18 g of a white solid with a purity of 98.89% and an mp of 194-196°C. The cumulative yield of six steps is 31.1%.

¹ H NMR(d ₆ -DMSO)δ0.84(d,6H,(CH ₃ ) ₂ CH)),1.62(t,2H,CH ₂ ),1,72(m,1H,CH(CH ₃ ) ₂ ),3.98(q,1H,CHNH ₂ ),4.11(m,1H,3'-CH),4.29(q,1H,4'-CH),4.46(m,2H,5'-CH ₂ ),6.11 (t,1H,1'-CH),6.18(d,1H,J=7.9Hz,5-CH),7.87(d,1H,J=7.9Hz,6-CH),8.59(s,2H,4 -NH ₂ ),8.67(s,2H,NH ₂ -CH);

ESI-MS(m/z):377.0[M+H] ⁺ ,399.0[M+Na] ⁺ ,415.0[M+K] ⁺ .

Example 62: S-2-amino-4-methylpentanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 2 of 4-difluoro-3-hydroxytetrahydrofuryl} methyl ester hydrochloride (5'-position L-leucine ester of gemcitabine, I _2e )

Using Boc-protected L-leucine instead of Boc-protected L-valine, and HBTU instead of EDCI, the reaction in Step 4 in Example 39 was carried out, and the yield was 87.4%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2e with a purity of 98.29%. The cumulative yield of six steps is 32.7%.

Example 63: S-2-amino-4-methylpentanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, 4-Difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (5'-position L-leucine ester of gemcitabine, I _2e ) preparation method three

The reaction in Step 4 in Example 39 was carried out with Boc-protected L-leucine instead of Boc-protected L-valine. HCOOH/n-BuNH ₂ was replaced by HCOOH/Et ₃ N to carry out the reaction in Step 5 in Example 39, and the yield was 65.0%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2e with a purity of 98.30%. The cumulative yield of six steps is 32.0%.

Example 64: S-2-amino-3-methylpentanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 1 of 4-difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (5'-position L-isoleucine ester of gemcitabine, I _2f )

Using Boc-protected L-isoleucine instead of Boc-protected L-valine, the reaction in Step 4 in Example 39 was carried out, and the yield was 88.1%. According to the procedure in Example 39, the remaining steps were carried out to prepare compound I _2f to obtain 1.02 g of a white solid with a purity of 98.46%, and mp 208-210°C. The cumulative yield of six steps is 31.6%.

¹ H NMR (d ₆ -DMSO)δ0.81(m,6H,CH ₃ CH ₂ ,CH ₃ CH),1.21(m,1H,CH ₂ CH ₃ ),1.91(m,1H,CH ₃ CH), 3.94(q,1H,CHNH ₂ ),4.09(m,1H,3'-CH),4.26(q,1H,4'-CH),4.43(m,2H,5'-CH ₂ ),6.10(t ,1H,1'-CH),6.18(d,1H,J=7.7Hz,5-CH),7.84(d,1H,J=7.7Hz,6-CH),8.69(s,2H,4-NH ₂ ),8.69(s,2H,NH ₂ -CH);

ESI-MS(m/z):377.1[M+H] ⁺ ,399.1[M+Na] ⁺ .

Example 65: S-2-Amino-3-methylpentanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method 2 of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-Position L-Isoleucine Ester, I _2f )

Using Boc-protected L-isoleucine instead of Boc-protected L-valine, and HOAt instead of EDCI, the reaction in step 4 in Example 39 was carried out, and the yield was 82.9%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2f with a purity of 98.16%. The cumulative yield of six steps is 30.8%.

Example 66: S-2-amino-3-methylpentanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method Three of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-Position L-Isoleucine Ester, I _2f )

The reaction in Step 4 in Example 39 was carried out with Boc-protected L-isoleucine instead of Boc-protected L-valine. HCOOH/n-BuNH ₂ was replaced by HCOOH/Et ₂ NH , and the reaction in Step 5 in Example 39 was carried out, and the yield was 63.8%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2f with a purity of 98.48%. The cumulative yield of six steps is 32.7%.

Example 67: S-2-amino-3-phenylpropanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 1 of 4-difluoro-3-hydroxytetrahydrofuryl}methyl ester hydrochloride (5'-position L-phenylalanine ester of gemcitabine, 1 _2g )

Using Boc-protected L-phenylalanine instead of Boc-protected L-valine, the reaction in Step 4 in Example 39 was carried out, and the yield was 90.4%. According to the steps in Example 39, the rest of the reaction steps were carried out to prepare _2g of compound I, and 1.17g of white solid was obtained, with a purity of 98.43%, and mp 242-244°C. The cumulative yield of six steps is 33.4%.

¹ H NMR(d ₆ -DMSO)δ3.12(q,2H,CH ₂ Ph),4.01(m,1H,CHNH),4.09(m,1H,3'-CH),4.32(m,2H,5 '-CH ₂ ),4.44(q,1H,4'-CH),6.07(t,1H,1'-CH),6.20(d,1H,J=7.8Hz,5-CH),7.24(m, 5H,Ph),7.78(d,1H,J=7.8Hz,6-CH),8.68(s,2H,4-NH ₂ ),8.68(s,2H,NH ₂ -CH);

ESI-MS(m/z):411.0[M+H] ⁺ ,433.0[M+Na] ⁺ ,449.0[M+K] ⁺ .

Example 68: S-2-amino-3-phenylpropionic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 2 of 4-difluoro-3-hydroxytetrahydrofuranyl}methyl ester hydrochloride (5'-position L-phenylalanine ester of gemcitabine, 1 _2g )

Using Boc-protected L-phenylalanine instead of Boc-protected L-valine, and HOBt instead of EDCI, the reaction in Step 4 in Example 39 was carried out, and the yield was 82.3%. According to the steps in Example 39, the remaining steps were carried out to prepare _2g of compound I with a purity of 98.15%. The cumulative yield of six steps is 32.1%.

Example 69: R-2-amino-3-phenylpropanoic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation method 1 of 4-difluoro-3-hydroxytetrahydrofuranyl} methyl ester hydrochloride (gemcitabine 5'-position D-phenylalanine ester, I _2h )

Boc-protected D-phenylalanine was used instead of Boc-protected L-valine to carry out the reaction in step 4 in Example 39, and the yield was 89.9%. Compound I _2h was prepared by following the steps in Example 39 to obtain 1.04 g of a white solid with a purity of 98.92% and mp 233-235°C. The cumulative yield of six steps is 34.9%.

¹ H NMR(d ₆ -DMSO)δ3.12(q,2H,CH ₂ Ph),3.91(m,1H,CHNH),4.23(m,1H,3'-CH),4.31(m,2H,5 '-CH ₂ ),4.37(q,1H,4'-CH),6.07(t,1H,1'-CH),6.14(d,1H,J=7.8Hz,5-CH),7.25(m, 5H,Ph),7.82(d,1H,J=7.8Hz,6-CH),8.66(s,2H,4-NH ₂ ),8.66(s,2H,NH ₂ -CH);

ESI-MS(m/z):411.1[M+H] ⁺ ,433.1[M+Na] ⁺ ,449.0[M+K] ⁺ .

Example 70: R-2-amino-3-phenylpropionic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4, Preparation Method 2 of 4-Difluoro-3-Hydroxytetrahydrofuranyl} Methyl Ester Hydrochloride (Gemcitabine 5'-position D-Phenylalanine Ester, I _2h )

The reaction in Step 4 in Example 39 was carried out with Boc-protected D-phenylalanine instead of Boc-protected L-valine. NDMBA was used instead of HCOOH/n-BuNH ₂ to carry out the reaction in Step 5 in Example 39, and the yield was 62.9%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2h with a purity of 98.28%. The cumulative yield of six steps is 32.7%.

Example 71: 2-Aminoacetic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro-3-hydroxyl Tetrahydrofuryl} methyl ester hydrochloride (gemcitabine 5'-glycinate, I _2i ) preparation method one

Using Boc-protected glycine instead of Boc-protected L-valine, the reaction in Step 4 in Example 39 was carried out, and the yield was 82.6%. According to the procedure in Example 39, the rest of the reaction steps were carried out to prepare compound I _2i to obtain 1.13 g of a white solid with a purity of 98.08%, and mp 202-204°C. The six-step cumulative yield is 30.8%.

¹ H NMR(d ₆ -DMSO)δ3.98(m,1H,3'-CH),4.09(m,2H,CH ₂ NH ₂ ),4.29(q,1H,4'-CH),4.48(m ,2H,5'-CH ₂ ),6.11(t,1H,1'-CH),6.24(d,1H,J=7.9Hz,5-CH),7.90(d,1H,J=7.9Hz,6 -CH),8.50(s,2H,4-NH ₂ ),8.85(s,2H,NH ₂ -CH);

ESI-MS(m/z):321.0[M+H] ⁺ ,343.0[M+Na] ⁺ .

Example 72: 2-Aminoacetic acid 2-{(2R,3R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4,4-difluoro-3-hydroxyl Tetrahydrofuryl} methyl ester hydrochloride (gemcitabine 5'-glycinate, I _2i ) preparation method two

The reaction in step 4 in Example 39 was carried out with Boc-protected glycine instead of Boc-protected L-valine. And using Dimedone instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 39 was carried out, and the yield was 63.2%. According to the steps in Example 39, the remaining steps were carried out to prepare compound I _2i with a purity of 98.23%. The cumulative yield of six steps is 31.0%.

Example 73: S-2-amino-3-methylbutanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-fluoro-3-hydroxyl

4.45(q,2H,5'-CH),6.16(t,1H,1'-CH),6.58(d,1H,J=7.9Hz,5-CH),7.94(d,1H,J=7.9Hz ,6-CH),8.56(s,2H,4-NH ₂ ),8.82(s,2H,NH ₂ -CH);

ESI-MS(m/z):359.2[M+H] ⁺ ,381.2[M+Na] ⁺ ,397.1[M+K] ⁺ .

Example 74: S-2-Amino-3-methylbutanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-valine ester, I _3a ) preparation method two

PSI-6130 was used instead of cytarabine, and CDI was used instead of EDCI to carry out the reaction in step 4 in Example 1, and the yield was 86.3%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3a with a purity of 98.48%. The cumulative yield of six steps is 31.1%.

Example 75: S-2-Amino-3-methylbutanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-valine ester, I _3a ) preparation method three

Cytarabine was replaced by PSI-6130, Pd(PPh ₃ ) ₄ was replaced by PdCl ₂ , and ligand PPh ₃ was added to the reaction system at the same time, the reaction in step 5 in Example 1 was carried out, and the yield was 66.3%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3a with a purity of 98.36%. The six-step cumulative yield is 30.2%.

Example 76: S-2-Amino-3-methylbutanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-valine ester, I _3a ) preparation method four

Using PSI-6130 instead of cytarabine and Dimedone instead of HCOOH/n-BuNH ₂ , the reaction in Step 5 in Example 1 was carried out, and the yield was 67.0%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3a with a purity of 98.23%. The cumulative yield of six steps is 31.8%.

Example 77: R-2-amino-3-methylbutanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-valine ester, I _3b ) preparation method one

Using PSI-6130 instead of cytarabine, Boc-protected D-valine instead of Boc-protected L-valine, and DCC instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 92.0%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3b with a purity of 98.81%. The cumulative yield of six steps is 31.1%.

¹ H NMR(d ₆ -DMSO)δ0.95(d,6H,(CH ₃ ) ₂ CH)),1.32(d,3H,CH ₃ CF),2.13(m,1H,CH(CH ₃ ) ₂ ) ,3.94(s,1H,CHNH),4.12(m,1H,3'-CH),4.31(q,1H,4'-CH),4.48(m,2H,5'-CH ₂ ),6.15(t ,1H,1'-CH),6.20(d,1H,J=7.8Hz,5-CH),7.87(d,1H,J=7.8Hz,6-CH),8.56(s,2H,4-NH ₂ ),8.70(d,2H,NH ₂ -CH);

ESI-MS(m/z):359.1[M+H] ⁺ ,381.1[M+Na] ⁺ .

Example 78: R-2-amino-3-methylbutanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-valine ester, I _3b ) preparation method three

Replace cytarabine with PSI-6130, replace Boc-protected L-valine with Boc-protected D-valine, and replace Pd(PPh ₃ ) ₄ with Pd(OAc) ₂ , and add ligand PPh to the reaction system at the same time ₃ , carry out the reaction of step 5 among the embodiment 1, yield is 68.3%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3b with a purity of 98.63%. The six-step cumulative yield is 30.9%.

Example 79: R-2-amino-3-methylbutanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method four of 4-fluoro-3-hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-valine ester, I _3b )

Using PSI-6130 instead of cytarabine, Boc-protected D-valine instead of Boc-protected L-valine, and NDMBA instead of HCOOH/n-BuNH ₂ , the reaction in step 5 in Example 1 was carried out, and the yield was 63.9%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3b with a purity of 98.52%. The cumulative yield of six steps is 31.7%.

Example 80: S-2-Alanine 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3 -Hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-alanine ester, I _3c ) preparation method one

Using PSI-6130 instead of cytarabine and Boc-protected L-alanine instead of Boc-protected L-valine, compound I _3c can be prepared through a similar preparation method as in Example 1, with a purity of 98.43%. The cumulative yield of six steps is 31.8%.

¹ H NMR (d ₆ -DMSO) δ1.32～1.38(d,d,6H,CH ₃ -CH,CH ₃ CF),3.84(q,1H,CHNH),4.08(m,1H,3'-CH ),4.30(q,1H,4'-CH),4.45(m,2H,5'-CH ₂ ),6.15(t,1H,1'-CH),6.20(d,1H,J=7.7Hz, 5-CH),7.80(d,1H,J=7.7Hz,6-CH),8.60(s,2H,4-NH ₂ ),8.75(d,2H,NH ₂ -CH);

ESI-MS(m/z):331.0[M+H] ⁺ ,353.0[M+Na] ⁺ ,368.9[M+K] ⁺ .

Example 81: S-2-Alanine 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3 -Hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-alanine ester, I _3c ) preparation method two

Using PSI-6130 instead of cytarabine, Boc-protected L-alanine instead of Boc-protected L-valine, and HATU instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 83.8%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3c with a purity of 98.41%. The cumulative yield of six steps is 32.9%.

Example 82: S-2-Alanine 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3 -Hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-alanine ester, I _3c ) preparation method three

Using PSI-6130 instead of cytarabine, Boc-protected L-alanine instead of Boc-protected L-valine, and HCOO ^- NH ₄ ⁺ instead of HCOOH/n-BuNH ₂ , carry out the reaction of step 5 in Example 1 , and the yield was 67.0%. The remaining steps were carried out according to the steps in Example 1 to prepare compound I _3c with a purity of 98.49%. The cumulative yield of six steps is 32.1%.

Example 83: R-2-Alanine 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3 -Hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-alanine ester, I _3d ) preparation method one

Using PSI-6130 instead of cytarabine, Boc-protected D-alanine instead of Boc-protected L-valine, compound I _3d can be prepared through a similar preparation method as in Example 1, with a purity of 98.10%. The cumulative yield of six steps is 32.6%.

¹ H NMR (d ₆ -DMSO) δ1.35～1.40(d,d,6H,CH ₃ -CH,CH ₃ CF),3.85(q,1H,CHNH),4.10(m,1H,3'-CH ),4.28(q,1H,4'-CH),4.42(m,2H,5'-CH ₂ ),6.12(t,1H,1'-CH),6.22(d,1H,J=7.9Hz, 5-CH),7.78(d,1H,J=7.9Hz,6-CH),8.56(s,2H,4-NH ₂ ),8.69(d,2H,NH ₂ -CH);

ESI-MS(m/z):331.1[M+H] ⁺ ,353.1[M+Na] ⁺ .

Example 84: R-2-Alanine 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3 -Hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-alanine ester, I _3d ) preparation method two

Replace cytarabine with PSI-6130, replace Boc-protected L-valine with Boc-protected D-valine, and replace Pd(PPh ₃ ) ₄ with Pd ₂ (dba) ₃ ·CHCl ₃ . The ligand PPh ₃ was added to carry out the reaction in Step 5 in Example 1, and the yield was 66.7%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _3d with a purity of 98.56%. The cumulative yield of six steps is 31.8%.

Example 85: R-2-Alanine 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3 -Hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-alanine ester, I _3d ) preparation method three

Using PSI-6130 instead of cytarabine, Boc-protected D-alanine instead of Boc-protected L-valine, and HCOOH/Et ₂ NH instead of HCOOH/n-BuNH ₂ , carry out the reaction of step 5 in Example 1 , and the yield was 65.3%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _3d with a purity of 98.62%. The cumulative yield of six steps is 32.8%.

Example 86: S-2-Amino-4-methylpentanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-leucine ester, I _3e ) preparation method one

Using PSI-6130 instead of cytarabine, and Boc-protected L-leucine instead of Boc-protected L-valine, compound I _3e can be prepared through a similar preparation method as in Example 1, with a purity of 99.04%. The cumulative yield of six steps is 34.3%.

¹ H NMR (d ₆ -DMSO)δ0.85(d,6H,(CH ₃ ) ₂ CH)),1.33(d,3H,CH ₃ CF),1.64(t,2H,CH ₂ (CH) ₂ ) ,1,73(m,1H,CH(CH ₃ ) ₂ ),3.96(q,1H,CHNH ₂ ),4.10(m,1H,3'-CH),4.28(q,1H,4'-CH) ,4.44(m,2H,5'-CH ₂ ),6.13(t,1H,1'-CH),6.20(d,1H,J=8.0Hz,5-CH),7.88(d,1H,J= 8.0Hz,6-CH),8.60(s,2H,4-NH ₂ ),8.72(s,2H,NH ₂ -CH);

ESI-MS(m/z):373.0[M+H] ⁺ ,395.0[M+Na] ⁺ ,411.0[M+K] ⁺ .

Example 87: S-2-Amino-4-methylpentanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-leucine ester, I _3e ) preparation method two

Using PSI-6130 instead of cytarabine, Boc-protected L-leucine instead of Boc-protected L-valine, and HBTU instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 80.5%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _3e with a purity of 98.67%. The cumulative yield of six steps is 33.0%.

Example 88: S-2-Amino-3-methylpentanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-isoleucine ester, I _3f ) preparation method one

Using PSI-6130 instead of cytarabine, and Boc-protected L-isoleucine instead of Boc-protected L-valine, compound I _3f can be prepared through a similar preparation method as in Example 1, with a purity of 98.87%. The six-step cumulative yield is 33.2%.

¹ H NMR(d ₆ -DMSO)δ0.82(m,6H,CH ₃ CH ₂ ,CH ₃ CH),1.20(m,1H,CH ₂ CH ₃ ),1.33(d,3H,CH ₃ CF), 1.90(m,1H,CH ₃ CH),3.95(q,1H,CHNH ₂ ),4.10(m,1H,3'-CH),4.25(q,1H,4'-CH),4.46(m,2H ,5'-CH ₂ ),6.12(t,1H,1'-CH),6.20(d,1H,J=7.8Hz,5-CH),7.85(d,1H,J=7.8Hz,6-CH ),8.68(s,2H,4-NH ₂ ),8.69(s,2H,NH ₂ -CH);

ESI-MS(m/z):373.1[M+H] ⁺ ,395.1[M+Na] ⁺ .

Example 89: S-2-Amino-3-methylpentanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-isoleucine ester, I _3f ) preparation method two

Using PSI-6130 instead of cytarabine, Boc-protected L-isoleucine instead of Boc-protected L-valine, and (Et ₂ NH ₂ ⁺ ) ₂ CO ₃ ^2- instead of HCOOH/n-BuNH ₂ , carried out The reaction of step 5 in embodiment 1, yield is 61.6%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _3f with a purity of 98.32%. The cumulative yield of six steps is 31.1%.

Example 90: S-2-Amino-3-phenylpropanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- Preparation method 1 of 4-fluoro-3-hydroxy-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-phenylalanine ester, I _3g )

Using PSI-6130 instead of cytarabine, and Boc-protected L-phenylalanine instead of Boc-protected L-valine, compound I _3g can be prepared through a similar preparation method as in Example 1, with a purity of 98.79%. The cumulative yield of six steps is 35.2%.

¹ H NMR(d ₆ -DMSO)δ1.35(d,3H,CH ₃ CF),3.15(q,2H,CH ₂ Ph),4.00(m,1H,CHNH),4.10(m,1H,3'-CH),4.33(m,2H,5'-CH ₂ ),4.45(q,1H,4'-CH),6.08(t,1H,1'-CH),6.18(d,1H,J=7.9 Hz,5-CH),7.25(m,5H,Ph),7.87(d,1H,J=7.9Hz,6-CH),8.70(s,2H,4-NH ₂ ),8.70(s,2H, _NH2 -CH);

ESI-MS(m/z):407.1[M+H] ⁺ ,429.1[M+Na] ⁺ ,445.0[M+K] ⁺ .

Example 91: S-2-Amino-3-phenylpropanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position L-phenylalanine ester, I _3g ) preparation method two

Using PSI-6130 instead of cytarabine, Boc-protected L-phenylalanine instead of Boc-protected L-valine, and HOAt instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 82.0%. According to the steps in Example 1, the remaining steps were carried out to prepare _3g of compound I with a purity of 98.50%. The cumulative yield of six steps is 31.5%.

Example 92: R-2-amino-3-phenylpropanoic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-phenylalanine ester, I _3h ) preparation method one

Using PSI-6130 instead of cytarabine, Boc-protected D-phenylalanine instead of Boc-protected L-valine, compound I _3h can be prepared through a similar preparation method as in Example 1, with a purity of 98.29%. The six-step cumulative yield is 34.8%.

¹ H NMR(d ₆ -DMSO)δ1.32(d,3H,CH ₃ CF),3.13(q,2H,CH ₂ Ph),4.03(m,1H,CHNH),4.12(m,1H,3'-CH),4.30(m,2H,5'-CH ₂ ),4.41(q,1H,4'-CH),6.10(t,1H,1'-CH),6.21(d,1H,J=7.8 Hz,5-CH),7.22(m,5H,Ph),7.85(d,1H,J=7.8Hz,6-CH),8.67(s,2H,4-NH ₂ ),8.67(s,2H, _NH2 -CH);

ESI-MS(m/z):407.0[M+H] ⁺ ,429.0[M+Na] ⁺ .

Example 93: R-2-amino-3-phenylpropionic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]- 4-Fluoro-3-hydroxyl-4-methyltetrahydrofuranyl} methyl ester hydrochloride (PSI-6130 5'-position D-phenylalanine ester, I _3h ) preparation method two

Use PSI-6130 instead of cytarabine, Boc protected D-phenylalanine instead of Boc protected L-valine, and Et ₂ NH ₂ ⁺ HCO ₃ ^- instead of HCOOH/n-BuNH ₂ , carry out in Example 1 The reaction of step 5 has a yield of 64.8%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _3h with a purity of 98.54%. The cumulative yield of six steps is 32.9%.

Example 94: 2-Aminoacetic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3-hydroxy- Preparation method 1 of 4-methyltetrahydrofuryl} methyl ester hydrochloride (PSI-61305'-glycinate, I _3i )

Using PSI-6130 instead of cytarabine, and Boc-protected glycine instead of Boc-protected L-valine, compound I _3i can be prepared through a similar preparation method as in Example 1, with a purity of 98.06%. The six-step cumulative yield is 30.2%.

¹ H NMR(d ₆ -DMSO)δ1.34(d,3H,CH ₃ CF),4.00(m,1H,3'-CH),4.10(m,2H,CH ₂ NH ₂ ),4.30(q, 1H,4'-CH),4.46(m,2H,5'-CH ₂ ),6.14(t,1H,1'-CH),6.26(d,1H,J=7.7Hz,5-CH),7.89 (d,1H,J=7.7Hz,6-CH),8.57(s,2H,4-NH ₂ ),8.82(s,2H,NH ₂ -CH);

ESI-MS(m/z):317.0[M+H] ⁺ ,339.0[M+Na] ⁺ .

Example 95: 2-Aminoacetic acid 2-{(2R,3R,4R,5R)-5-[4-amino-2-oxo-1(1H)-pyrimidinyl]-4-fluoro-3-hydroxy- Preparation Method 2 of 4-Methyltetrahydrofuranyl} Methyl Ester Hydrochloride (PSI-61305'-Glycine Ester, I _3i )

Using PSI-6130 instead of cytarabine, Boc-protected glycine instead of Boc-protected L-valine, and HOBt instead of EDCI, the reaction in step 4 in Example 1 was carried out, and the yield was 62.3%. According to the steps in Example 1, the remaining steps were carried out to prepare compound I _3i with a purity of 98.36%. The cumulative yield of six steps is 30.7%.

Claims (14)

1. the Regioselective synthesis of nucleoside medicine 5'- bit amino acid esters are it is characterised in that selected using triaryl methyl Protect to selecting property nucleoside medicine 5'- position hydroxyl, then utilize allyloxycarbonyl protection nucleoside medicine base portion and sugar knot Structure partly in avtive spot, more acid lower selectively removing triaryl methyl, so the amino acid condensation with Boc protection, 5'- position in nucleoside medicine molecule optionally becomes ester, then palladium chtalyst removing allyloxycarbonyl, under acid condition Removing Boc simultaneously becomes corresponding salt, comprises the following steps that：

(1) formula VII becomes ether that formula VI is obtained with triaryl methyl reagent；

(2) formula VI and the condensation of allyloxycarbonyl reagent are obtained formula V；

(3) triarylmethyl protecting group group in selectively removing 5'- position is obtained formula IV to formula V in acid condition；

(4) a-amino acid that formula IV is protected with corresponding Boc is condensed into ester and general formula III is obtained；

(5) general formula III removes all of AOC protection group under homogeneous palladium catalytic condition and formula II is obtained；

(6) formula II under acid condition, conventional method removing Boc and be obtained the corresponding salt of formula I；

Wherein：

Formula I～VII structural formula is respectively：

Wherein, base Base part be natural pyrimidine base base class, purine base base class or their structural modification base class；X For carbon atom, oxygen or sulphur atom；R in Formula VII, VI, I, II₂Or R₃For hydroxyl, and deposited with the arbitrary configuration in R- type or S- type In the R in Formula V-III₂Or R₃Hydroxyl for allyloxycarbonyl protection；RCH (the NH of 5'- position₂) COO- ester bond part aminoacid Come from various natural or engineered a-amino acid RCH (NH₂) COOH, wherein aminoacid is glycine, alanine, figured silk fabrics ammonia Acid, leucine, isoleucine, Phenylalanine, proline, Gamma Amino Butyric Acid, and existed with L-type, D- type or racemate form.

2. synthetic method according to claim 1 it is characterised in that obtain base nucleosides 5'- bit amino acid esters and its Pharmaceutical salts.

3. synthetic method according to claim 2 is it is characterised in that described salt deoxygenates -2'- fluoro- 2'-C- first for 2'- The 5'- bit amino acid esters dihydrochloride of base cytidine.

4. synthetic method according to claim 1 is it is characterised in that in step (1), described triaryl methyl reagent For trityl chloride, trifluoromethanesulfonic acid three benzene methyl, two (p-methoxyphenyl) phenyl methyl chlorine, three p-methoxyphenyl methyl chlorides.

5. synthetic method according to claim 1 is it is characterised in that step (1) or (2) are carried out, instead in the basic conditions Alkali that should be used is organic base or inorganic base, and described organic base is pyridine, dimethylamino naphthyridine, triethylamine, diisopropyl second Base amine or DMA, inorganic base is sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide or hydroxide Potassium.

6. synthetic method according to claim 1 is it is characterised in that reaction dissolvent in step (1), (2), (4) or (5) For pyridine, dichloromethane, dichloroethanes, chloroform, ether, benzene,toluene,xylene, chlorobenzene, methyl tertiary butyl ether(MTBE), diisopropyl Ether, oxolane, 2- methyltetrahydrofuran, 1,2- dimethoxy-ethane, 1,4- dioxane, N,N-dimethylformamide, N, N- dimethyl acetylamide, or the various combination of above-mentioned solvent, reaction temperature is -20 DEG C～solvent reflux temperature.

7. synthetic method according to claim 1 is it is characterised in that in step (2), described allyloxycarbonyl reagent For 1- allyloxycarbonyl tetrazolium, 1- (allyloxy carbon epoxide) -1H- benzotriazole, allyl chlorocarbonate.

8. synthetic method according to claim 1 is it is characterised in that in step (2), described allyloxycarbonyl reagent For allyl chlorocarbonate.

9. synthetic method according to claim 1 is it is characterised in that in step (3), the acid in described acid condition is chlorine Change hydrogen, formic acid, glacial acetic acid, trifluoroacetic acid or p-methyl benzenesulfonic acid；This reaction select solvent be selected from 1～6 carbon alcohols solvent, Ethereal solvent or esters solvent, described alcohols solvent is selected from methanol, ethanol, normal propyl alcohol, isopropanol, n-butyl alcohol, isobutanol, uncle Butanol or the various combination of these solvents；Described ethereal solvent is selected from ether, methyl tertiary butyl ether(MTBE), Di Iso Propyl Ether, tetrahydrochysene Furan, 2- methyltetrahydrofuran, the various combination of 1,2- dimethoxy-ethane, 1,4- dioxane or these solvents；Described Esters solvent is selected from methyl acetate, ethyl acetate, butyl acetate, or is water, or the various combination of above-mentioned solvent, reaction temperature For -20 DEG C～solvent reflux temperature.

10. synthetic method according to claim 1 is it is characterised in that in step (4), the condensing agent of reaction is N, N'- bis- Carbodicyclo hexylimide, 1- ethyl -3- (3- dimethylamine propyl) carbodiimide hydrochloride, carbonyl dimidazoles, 2- (7- azo benzo Triazole)-N, N, N', N'- tetramethylurea hexafluorophosphoric acid ester, 2- (7- azo BTA)-tetramethylurea hexafluorophosphoric acid ester, 1- hydroxyl -7- azo BTA, I-hydroxybenzotriazole；Catalyst is DMAP, pyridine, triethylamine or two Wopropyl ethyl amine.

11. synthetic methods according to claim 1 it is characterised in that in step (4), the condensing agent of reaction be 1- ethyl- 3- (3- dimethylamine propyl) carbodiimide hydrochloride.

12. according to claim 1 synthetic method it is characterised in that palladium catalyst in step (5) is four (triphenylphosphines) Palladium, Palladous chloride., palladium, three (dibenzalacetone) two palladium.

13. synthetic methods according to claim 1 are it is characterised in that the catalyst of reaction is combined with organophosphine ligand Coordination, from neutral or faintly acid nucleopilic reagent, selected from 1,1-Dimethyl-3,5-diketocyclohexane, 1,3- dimethyl barbituric acid, formic acid, acetic acid, primary amine, secondary Amine and the mixture of formic acid or carbonic acid.

14. synthetic methods according to claim 13 are it is characterised in that described nucleopilic reagent is selected from ammonium formate, formic acid Positive fourth ammonium, formic acid diethyl ammonium, carbonic acid diethyl ammonium, bicarbonate diethyl ammonium.