CA1332169C - Process for the preparation of fused pyridine compounds - Google Patents

Abstract

PROCESS FOR THE PREPARATION OF FUSED PYRIDINE COMPOUNDS

ABSTRACT

2-Amino-4-hydroxy-6-[2-(4-carboxyphenyl)alk-1-en-1-yl]pyrido[2,3,-d]pyrimidines and 2-amino-4-hydroxy-6-[2-(4-carboxyphenyl)alk-1-yn-1-yl]pyrido[2,3-d]pyrimi-dines are prepared through the reaction of a halo-aromatic compound and an unsaturated compound in the presence of a palladium catalyst. The products are chemical intermediates for the preparation of antineo-plastic agents. A typical embodiment is the reaction of a protected 2-amino-4-hydroxy-6-ethynylpyrido[2,3-d]
pyrimidine and an ester of 4-iodobenzoic acid.

Description

1~32169 ~

960-l05 PROCESS FOR THE PREPARATION OF F~SED PYRIDINE COMPOUNDS

This invention pertains to a process for the prepa-ration of known therapeutic agents and to chemical 5 intermediates useful therein. `~

Background of the Invention ;~
~:, Compounds of the formula: ~
~:, OH

11~ CH-CH2-CH ~3-col:H-cN-cH2cN2cooH
- ~ ~ , CH2 COOH
; H2N N H

in which z2 is hydrogen, methyl, or ethyl are broad spectrum antineoplastic agents, see published PCT Appli- ~ ;~
cation WO 86/05181. N-(4-12-(2-amino-4-hydroxy-5,6,~,8-~,., tetrahydropyridol2,3-d]pyrimidin-6-yl)ethyl]benzoyl)-L- '~,', glutamic acid, which is representative, has been pre-`~ 20 pared~previously through an eighteen step synthesis in ~r~ which a 2-~prote~ted amino)-4-hydroxy-6-12-(4-carboxy-phenyljethenyl]pyridol2,3-dlpyrimidine is coupled with a `-diester of L-glutamic acid utilizing peptide condensa-tion techniques. The resultant dialkyl N-(4-12-(2-pro- ;
tected amino-4-hydroxypyrido12,3-d]pyrimidin-6-yl)-ethenyl]benzoyl)-L-glutamate is then hydrogenated, fol-~, lowing which the protecting groups are removed [see Taylor e~ al., J. Med. Chem. 28:7, 914 (l985) . :., ~; . . ', ,'. ,~`~
'.` ~ ~'' ' '~' ' Detailed Descrl~tion The present invention involves a simplified process .
for the preparation of important intermediates useful in the synthesis of the foregoing compoundst in particular, intermediates of the formula:

C _ C~3-CoR
N~, ~
4 ~ ~ ~ (I) R HN N N

wherein R i5 NHCH (COOR ) CH2CH2COOR2 or oR2;
1~ R is hydrogen or a carboxylic acid protecting group; ~ -R4 is hydrogen or an amino protecting group;
zl when taken independently of Z2 iS hydrogen: and ~.~
z2 when taken independently of zl is hydrogen, :-methyl or ethyl: or zl and z2 when taken together are a carbon-carbon ~:~ 20 bond~
A number of compounds falling within Formula ~ in which zl is hydrogen and Z is hydrogen, methyl or ethyl ~ :
are known from PCT Application No. WO 86/05181; others ~"~` wherein zl and z2 are a carbon-carbon bond are novel and `~ 25 constitute part of the present.invention.
The process involves the step of allowing an ' unsaturated compound (as hereinafter 'efined) to react with a haloaromatic compound (as also hereinafter de-fined) in the presence of a palladium catalyst. The reaction has a number of different embodiments but each of these has in common the use of an organopalladium reactant which is generated from a palladium complex and ;;

,' 13~21~

the haloaromatic compound and which reacts with the unsaturated compound.
The palladium complexes are those which have been employed previously in the reaction of aryl halides and ~ `
allylic alcohols, as described for example by Melpoler ¦ et al., J. Orq. Chem., 41, No. 2, 1976, 265; Chalk et ¦ al., J. Or~. Chem., 41, No. 7, 1976, 1206; A~ai et al., 'I J. Heterocyclic Chem., 15, 351 (1978); Tamuru et al., ¦ Tetrahedron Papers, 10, 919 (1978) 919; Tetrahedron, 35, 1 10 329 (1979). Particularly useful are the palladium/tri-substituted-phosphine complexes of 5akamoto, Synthesis, 1983, 312; e.g., a trisubstituted-phosphine such as a triarylphosphine, as for example triphenylphosphine, or a trialkylphosphine; a palladium salt such as palladium 1 15 acetate or a palladium halide such as palladium chloride: and a cuprous halide, such as cuprous iodide.
The reaction preferably is conducted in the pres-ence of at least one molar equivalent of a secondary or -tertiary amine which acts as an acid acceptor, as for 20 example triethylamine, or diethylamine, and under an ~
înert atmosphere, optionally in the presence of an inert -I
polar solvent such as acetonitrile, dimethylformamide, N-methylpyrrolidone and the like. Particularly pre-ferred is the use of acetonitrile which serves as a solvent not only for the reactants but also for the salt formed from the acid acceptor and acid generated. Mod-erately elevated temperatures, as for example from about 75 to 125C, preferable at or below 100C, generally ~ .
are advantageous.
The following four embodiments utilize the fore-, i I going palladium catalysts and differ in the nature of haloaromatic compound and unsaturated compound employed as the reactants. Haloaromatic compounds as herein used ~`- include halopyridines, fused halopyridines and halo-benzoic acid derivatives. The unsaturated compound includes both alkenes and alkynes as well as pyridines, fused pyridines and benzoic acid derivatives substituted ',;
: , ~ ~ .",'`' ~; ";, ~.. ~" ~ ."

with an alkenyl or alkynyl group.
In a first embodiment, the haloaromatic compound is a pyridine of the formula:

R30Co X
,~ J ~II) Y N

wherein :~
: Y is amino or.a nucleofuge; -X is bromo or iodo; and -R is alkyl of 1 to 4 carbon atoms.
;~ The haloaromatic compound of Formula ~I is allowed to react with an unsaturated compound of the formula:

zll z2 (III) ~ 15 HC= C-Q
"~
wherein ~: zl when taken independently of z2 is hydrogen;
Z when taken independently of Z is hydrogen, :
methyl or ethyl; or zl and z2 when taken together ar~ a carbon-carbon bond, and i~ : : Q is a trisubstituted silyl group or a benzoyl group of the formula:

>-COR

wherein l is -NHCH(COOR2)CH2CH2COOR2 or oR2; and R2 is a carboxylic acid protecting group.
In a second embodiment, the haloaromatic compound is a fused pyridine of the formula~
`~
~.,: , `'-'.' ',~:: , ., . ,.

~; , . , ; ' '', ,".'; :~, ~- ,;` ` . '~ ~ ' ; `

--`` 1332169 ........
011 ~ ' '~

R4HN ~ N N
",.....

wherein R4 is hydrogen or an amino protecting group and .
X is bromo or iodo. ~; -A compound of Formula IV is allowed to react with an ~:~
unsaturated compound of Formula III, discussed above, in :~
the presence of the palladium catalyst.
In a third embodiment, the haloaromatic compound is ~ of the formula~

.~ ~ X ~ -CORl (V) wherein X is bromo or iodo: 2 2 R is -NH-CH(COOR )CH2CH2COOR or OR ; and R is:a carboxylic acid protecting group; - ;~
and the unsaturated` compound is a pyridine of the fo~mu1a:
20~: zl z2 R30Co ~ C~ CH (VI) :~

~ Y 3~ N ~

wherein ,~ Y is amino or a nucleofuge;
Zl:when taken independently of z2 is hydrogen; -:;~
:~ z when taken independently.of Z is bydrogen, "`: ~
' :; .' ~ 1332169 methyl or ethyl; or zl and z2 when taken together are a carbon-carbon bond; and R3 is alkyl of 1 to 4 carbon atoms.
In a fourth embodiment, a haloaromatic compound of Formula V above is allowed to react with a pyrido-[2,3-dlpyrimidine of the formula:

OH zl z2 N ~ C= C-H (VII) R4HN N N `:

wherein ~ R4 is hydrogen or an amino protecting group;
.~ zl when taken independently of z2 is hydrogen;
and z2 when taken independently of zl is hydrogen, mlethyl 2 ethyl; or ~
Z and Z when taken together are a carbon-carbon ~:
~; bond. :
In the first embodiment set forth above when Q is the depicted 4-carboxyphenyl group, and in the third embodiment, there is produced a novel intermediate of :
the formula~

2 :~
~5 R30Co ~ C~ C ~ -CORl ~VIII) ,~

-' 1332169 ~

When allowed to react with guanidine the inter-mediates of Formula VIII are converted directly to a 2-amino-4-hydroxy-6-substituted-pyridol2,3-d]pyrimidine of Formula I in which R is hydrogen.
In the second and fourth embodiments, a compound of Formula I is formed directly.
In the above reactions, R preferably is an alkyl group such as methyl, ethyl, sec.-butyl, t-butyl, or another known carboxylic acid protecting group such as nitroben2yl, 4-methoxybenzyl, diphenylmethyl, trichloro-ethyl, l-ethoxyethyl, l-ethylthioethyl, and the like.
When Rl is the depicted glutamic acid residue twhich will be of L-configuration), typically the compound will"!"' be a $-glutamic acid dialkylester such as the dimethyl, -diethyl, or di-(tert.-butyl) ester.
I The compounds of Formula II can be prepared by ¦ esterification of the known 1,2-dihydro-2-oxo-3-pyridine ! ~ carboxylic acid, introduction of a 5-iodo or S-bromo group through treatment with N-iodosuccinimide or N-bromosuccinimide to yield the S-iodo- or 5-bromo-2-oxo-1,2-dihydro-3-pyridine carboxylate, respectively, and replacement of the 2-oxo group with a suitable nucleofuge; e.g., chlorination with phosphorus oxy-chloride. The term "nucleofuge~ refers to a conven-tional leaving group which is replaced by nucleophilicreagents. ISee Organic Chemistry, Morrison and Boyd, Allyn and Breur, 4th Edition, p 205]. Typical nucleo-fuges thus include ~hloro, bromo, iodo, an aryl or alkylsulfinyl or sulfonyl group of up to 10 carbon atoms, an arylthio or alkylthio group of up to 10 carbon atoms, mercapto, and alkoxy of up to 10 carbon atoms.
Preferably Y is chloro. X may be bromo or iodo; iodo is preferred.
Compounds of Formula IV can be prepared through the condensation of 2,4-diamino-6-hydroxy-pyrimidine and a halomalonaldehyde, such as bromomalonaldehyde or iodo-~ malonaldehyde, preferably bromomalonaldehyde.

h~

1332:169 Alternatively, compounds of Formula IV can beobtained from a pyridine of Formula II through treatment with guanidine in a manner analogous to that described above, followed by optional protection of the amino S group, as for example by acylation.
Compounds of Formula VI and VII can be prepared from starting materials of Form~las Il and IV, respec-tively, by utilization of an unsaturated compound of Formula III in which Q is a trisubstituted silyl pro-tecting group, followed by hydrolysis of the silylgroup.
The amino and carboxylic acid protecting groups discussed herein are those conventionally employed, as described for example b~ Greene in ~Protective Groups in Organic Synthesis", John Wiley ~ Sons, Inc., 1981, and McOmie in ~Protective Groups in Organic Chemistry~, Plenum Press, 1983. Particularly preferred R4 protec-ting groups are alkanoyl groups such as acetyl, pro-pionyl, pivaloyl, and the like.
Catalytic hydrogenation of a compound of Formula I ~-yields the corresponding 2-amino(or 2-protected amino)-~; 4-hydroxy-6-substituted-5,6,7,8-tetrahydropyridol2,3-d]-~;~ pyrimidine of the formula:
OH

~ 25 ~ ~¦ fH-CH2-C~ ~ coRl (IX) I ~ ~ R4HN ~ N ~ ~ 2 H

in which R4 is hydroyen or an amino protecting group and l and z2 are as defined above. 1 -~
When in the compounds of Formula IX R ~8 ::~
-NH(CooR2)cH2cH2cooR and Z is hydrogen, the resulting product is a protected derivative of the known [N-(4-12 (2-amino-4-hydroxy-5,6,7,8-tetrahydropyridol2,3-d]~
pyrimidin-6-yl)ethyl]benzoyl3-L-glutamic acid; e.g., '~

diethyl N-~4-l2-(2-amino-4-hydroxy-5,6,7,8-tetrahydro-pyridol2,3-d]pyrimidin-6-yl)ethyl]benzoyl)-L-glutamate (or the protected amino derivative thereof), which then is subjected to hydrolysis or hydrogenolysis as pre-viously described to remove the protecting groups andyield the known N-(4-l2-~2-amino-4-hydroxy-5,6,7,8-tetrahydropyridol2,3-d]pyrimidin-6-yl)ethyl~benzoyl)-L-glutamic acid.
Alternatively, if in the compounds of Formula IX, Rl is _oR2 in which R2 is a carboxylic acid protecting group, the protecting group is removed in a known fash-ion, as for example~ hydrolysis with hydrogen chloride in nitromethane, to yield 2-amino-4-hydroxy-5,6,7,8-tetra-hydro-6-12-(4-carboxyphenyl)ethyl~pyrido[2,3-d~
pyrimidine:
- OH

N ~ ~ ~ CH-CH2-CH ~ -COOH
20 ~2N ~ N ~ ~ N ~ ~X) ~ Following protection of the 2-amino group, as for ;~ 25 example conversion to the N-pivaloyl derivative, a com-pound of Formula IX is then coupled with a protected glutamic acid derivative in the manner described in PCT
-~ application WO 86/05181. The coupling reaction utilizes conventional condensation techniques for forming peptide bonds, such as activation of the carboxylic acid through formation of the mixed anhydride, treatment with DCC, or use of diphenylchlorophosphonate.
The hydrogenation of a compound of Formula I to a compound of Formula IX or Formula X generates a chiral 35 center at the 6-position of the 5,6,7,8-tetrahydro-pyridol2,3-d]pyrimidine ring. If z2 is other than hydrogen, a second chiral center is generated in the .~

~332169 course of hydrogenation. In one embodiment of the present invention, the group R in Formula I itself con-tains a chiral center and is in one of its chiral forms substantially free of the other. Thus R can be the depicted L-glutamic acid group which itself is chiral.
Alternatively, R2 in the group -OR in formula I is one enantiomeric form of a chiral group such as sec.-butyl, 2-methylbut-1-yl, l-phenylethyl, (lR,2S)-~-)ephedrine, l-hydroxyprop-2-yl, l-ethoxyethyl, l-ethylthioethyl, the residue of a chiral terpene alcohol such as (lS,2R,5R)~
(+)-isomentholl (lR,2R,3R,5S)-(-)-isopinocampheol, (S)-perillyl alcohol, lllS)-endo]-(-)-borneol, and the like. Use of a single chiral form of the protecting group R yields a mixture of two diastereomers upon hydrogenation of a compound of Formula I in which Z is hydrogen~
~ (S)~

C H2 CH2 ~ -COOR2 (XI~

H ~

.
~R):
OH

R N ~ ~ CH2-CH2 ~ -COOR2 (XIB) where R2 is a chiral form of R2 substantially free of itS enantiomer. The product of the hydrogenation is a , ' .
:
: " ~'' ~ .:

~ ~3321~9 mixture of two diastereomers which can be directly separated by taking advantage of their different so'u-bility properties, thus eliminating the need for an independent separation step, as for example formation of a salt with a chiral acid.
Analogously if Z is methyl or ethyl, use of a chiral R2 group produces a mixture of four diastereo-mers, e.g., (R,R,R2 ), (R,S,R ), (S,S,R ) and (S,R,R2 ) which are similarly separated.
The residue of the chiral alcohol is then hydro-lytically removed from the individual separated dia-stereomers and which in the form of the free carboxylic acid is then coupled with a protected glutamic acid derivative as previously discussed.
The following examples will serve to further typify the nature of this invention but the invention should ~; not be construed as being limited to these embodiments.
1,~
Exam~le_l Methyl 2-chloro-5-iodo-3-pyridinecarboxylate A. Methyl 2-Oxo-1,2-dihydro-3-pyridinecarboxylate A mixture containing 27.8 9 of 1,2-dihydro-2-oxo-3-pyridinecarboxylic acid, 3.0 ml of concentrated sul-furic acid in 500 ml of methanol, and 300 ml of benzene are heated under reflux for 2.5 hours. A Dean-Stark trap is then attached, and the azeotrope collected is `~ removed periodically in 25 ml fractions over a period of 28 hours. $he remaining solvent is romoved by evapora-tion under reduced pressure and the solid residue sus-pended in 500 ml of cold water. The suspension is filtered (from which unreacted starting material can be recovered) and the filtrate continuously extracted with methylene chloride. The extracts are concentrated under reduced pressure to yield the title compound as a white solid which, upon recrystallization from 1.4 L of ben-zene, yields 19.48 9 (64%) of methyl 2-chloro-5-iodo-::

1332169 ~ ~

3-pyridinecarboxylate: m.p. 14B-151C; NMR ~DMSO^d6, 80 MHz) delta 3.~2 (s, 3H)~ 6.25 ~dd, lH, J=7.1 Hz, J=6.3 Hz), 7.64 (dd, lH, J=6.3 Hz, J-2.2 Hz), 8.03 (dd, lH, J=7.1 Hz, J=2.2 Hz).
Ethyl 2-oxo-1,2-dihydro-3-pyridinecarboxylate is -~
obtained in an analogous fashion utilizing ethanol in place of methanol.

B. Methyl 5-iodo-2-oxo-1,2-dihydro-3-pyridinecarboxylate A solution containing 19.4~ g of methyl 2-oxo-1,2- -~
dihydro-3~pyridinecarboxylate and 36.15 9 of N-iodo-succinimide in 500 ml of anhydrous methylene chloride is heated at reflux under a nitrogen atomosphere in the dark for 48 hours. The reaction mixture is concentrated ;~
to 150 ml under reduced pressure and the solid which 15 forms is collected by filtration and washed with small ~-~
portions of cold methylene chloride and benzene to give 16.59 g (47~) of methyl 5-iodo-2-oxo-1,2-dihydro-3- ;~
pyridinecarboxyiate as a pale yellowish solid. This -~ material is sufficiently pure for the next reaction; its `~ 20 properties upon recrystallization from ethyl acetate are ;~ as follows: m.p. 190-192C; NMR (DMSO-d6, 300 MHz) delta 3.11 (s, 3~), 7.93 (d, lH, J=2.26 Hz), 8.10 (d, lH, J=2.26 Hz), IR (KBr) 2500-3050 (broad), 1725, 1630, 1585, 1475, 1425, 1320, 1260, 1235, 1180, 1150, 1105, 1065, -~
965, 87~ and 800 cm ; M/S (279, M+), 247, 127 and 93. -~
`~ Anal. Calcd. for C7H6INO3: C, 30.13; H, 2.17; I, 45.48;
N, 5!02 Found: C, 30.24; H, 2.22; I, 45.55: N, 4.87. -The filtrate is evaporated and the residue dissolved in ; 30 500 ml of methylene chloride. The organic solution is extracted with a 10~ sodium thiosulfate solution, washed with a saturated sodium chloride solution, and dried `~ over anhydrous sodium sulfate. The solution is concen~
trated under reduced pressure and the residue triturated -~
;;35 with ethyl acetate and filtered to yield an additional ~;~
5.49 g (15%) of methyl 5-iodo-2-oxo-1,2-dihydro-3- ;~
pyridinecarboxylate.

. ''""~
. :~
. ,~

",~ 1332l69 ~tilization of an equivalent amount of ~-bromo-succinimide yields the corresponding methyl 5-bromo-2-oxo-1,2-dihydropyridine-3 carboxylate. m.p. 181-182~C;
NMR (DMSO-d6, 300 MHz) delta 3.72 (s, 3H), 7.97 (d, lH, J=2.80 Hz), 8.05 (d, lH, J=2.80 Hz); IR (KBr) 2S00-3200 (broad), 1735, 1~00, 1665, 1595, 1545, 1480, 1440, 1370, 1190, 1160, 1120, 970, 900, and 800 cm 1.

C. Methyl 2-Chloro-5-Iodo-3-pyridinecarboxylate Procedure 1: To a mixture containing 2.0 9 of methyl 5-iodo-1,2-dihydro-3-pyridinecarboxylate, 1.6 9 of diethylaniline, 1.64 9 of benzyltriethylammonium chlor-ide and 3.6 ml of distilled phosphorus oxychloride in 100 ml of dry acetonitrile are added 15 drops of water.
The mixture is heated under reflux for 18 hours. After cooling the reaction mixture to room temperature, the solvent is removed under reduced pressure and the resi-due taken up in methylene chloride and extracted with water. The organic solution is dried over anhydrous sodium sulfate and concentrated under reduced pressure.
The residue is chromatographed on a column of ~lash silica gel using methylene chloride as the eluent.
Evaporation of the eluent yields a pale yellowish solid which is recrystallized from aqueous ethanol to give 1.1 9 (524) of methyl 2-chloro-5-iodo-3-pyridinecarb-oxylate as a white solid: m.p. 73-73.5~C: NMR (80 MHz, CDC13) delta 3.96 (s, 3H), 8.43 (d, lH, J-ii2.3 Hz), 8.71 ~d, lH, J-2.3 Hz)~
:~
:~
Procedure 2: To a solution containing 0.12 ml of dry dimethylformamide and 0.14 ml of distilled phosphorus oxychloride in 20 ml of anhydrous methylene chloride are added 0.28 9 of methyl S-iodo-1,2-dihydro-3-pyridine-carboxylate in one portion. The mixture is stirred at room temperature under a nitrogen atmosphere for 28 hours~ Workup as described in Procedure 1 yields 0.13 9 3S (43~) of recrystallized methyl 2-chloro-5-iodo-3-pyridinecarboxylate.
.~

13321~9 -14- ;~
Analogously prepared is methyl 2-chloro-5-bromo-3-pyridinecarboxylate, m.p. 49-50'~C; NMR (CDC13, 300 MHz) delta 3.99 (s, 3H), 8.32 (d, lH, J=2.86 Hz), 8.60 (d, lH, J=2.86 Hz). Ethyl 2-chloro-5-iodo-3-pyridine-carboxylate and ethyl 2-chloro-5-bromo-3-pyridinecarb-oxylate can be prepared in the same fashion.

Example_2 -~
tert.-8utyl 4-Ethynylbenzoate "~
A. tert.-Butyl 4-Bromobenzoate ~1 To a mixture of 5.5 9 of dry tert.-butanol and 7.08 9 of dry pyridine i8 added a solution of 9.79 9 of 4-bromoben20yl chloride in 20 ml of anhydrous methylene chloride. The mixture is stirred under nitrogen for 2 days. The reaction mixture is then diluted with methyl-ene chloride, and the organic solution extrac~ed with water, dried over anhydrous sodium sulfate, and concen- ~-trated under reduced pressure. The residual oil is dis- ;~
~ tilled under reduced pressure to give 8.9 9 ~70~i) of `~ tert.-butyl 4-bromobenzoate as a colorless oil: b.p.
91-92C/1.2 mm; NMR (CDC13, 80 MHz) delta 1.59 (s, 9H), 7.53 (d, 2H, J~8.7 HZi); IR (neat) 2970, 1710, 1585, ~-1475, 1390, 1290, 1160, 1110, 10~0, 845 and 745 cm 1. ~;
Anal. Calcd. ~or CllH13Br~2 31.08.
Found: C, 51.41; H, 5.36; Br, 30.38.
:
:~
. ~
B. tert.-Butyl 4-Ethynylbenzoate ;~ A mixture containing 1.31 9 of tert.-butyl 4-bromo-benzoate, 1.0 9 of trimethylsilylacetylene, 10 mg of palladium acetate and 15.6 mg of triphenylphosphine in ~ 30 15 ml of anhydrous triethylamine is heated in ~ sealed 1~ container at }00C for 16 hours. After cooling to room temperature, the reaction mixture is diluted with ~
methylene chloride and extracted with water. The ~-organic solution is dried over anhydrous sodium sulfate -- ~
... ~ ~
:. -;.':. .
'.'"''' ~:' . ~
':. ..-'' ~ ~332169 and the solvent removed under reduced pressure. The dark residue is chromatographed a a column of flash silica gel using a 10% ethyl acetate-hexanes mixture as the eluent to give tert.-butyl 4-(trimethylsilylethynyl-benzoate as a dark oil: NMR (CDC13, 300 MHz) delta 0.26 (s, 9H), 1.59 (s, 9H), 7.49 (d, 2H, J=8.23 Hz), 7.91 (d, 2H, J=8.~3 Hz). This is dissolved in 20 ml of anhydrous methanol, and then treated with 0.1 9 of anhydrous potassium carbonate. The mixture is allowed to stir at room temperature under nitrogen for 3 hours. The reac-tion mixture is diluted with methylene chloride, ex-tracted with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue is distilled under reduced pressure (60-70C/0.1 mm to give 0.75 9 (73% over 2 steps) of tert.-butyl 4-ethynylbenzo-ate as a white solid: m.p. 71.5-72C; NMR (CDC13, 80 MHz~ delta 1.62 (s, 9H), 3.23 (s, lH), 7.55 (d, 2H, J=8.11 Hz), 7.96 (d, 2H, J=8.11 Hz); IR (RBr) 3240, 2970, 2100, 17~0, 1600, 1450, 1365, 1300, 1250, 1160, 1115, 1015, 845 and 765 cm 1; M/S 202 M~), 187, 157, ~ 146, 129, 101, 75 ar.d 57.
¦ Anal. Calcd. for C13H14O2 Found: C, 76.86: H, 6.79.

Example 3 ethyl 5-~4-tert.~h~xy___bonylphenyl-ethynyI)-2-chloro-3-~yridinecarboxylate To a solution containing 0.53 9 of methyl 2-chloro-5-iodo-3-pyridinecarboxylate and 0.4 9 of tert.-butyl 4-ethynylbenzoate in 30 ml of triethylamine is added 0.19 9 of triphenylphosphine, 0.06 9 of palladium chlor-ide, and 0.03 9 of cuprous iodide. The mixture is heated under reflux under a nitrogen atmosphere for 4 hours. The solvent is removed under reduced pressure and the residue is ~ubjected to radial chromatography on silica gel using methylene chiloride as the eluent. The i~ :

~" 1332169 .

major fraction isolated from the plate contained 0.43 9 (65~) of methyl 5-(4-tert.-butoxycarbonylphenylethynyl)-2-chloro-3-pyridinecarboxylate as a pale yellowish oil which crystallized on standing. A small portion of this -~
material is recrystallized from hexanes: m.p. 123-124~C;
NMR (CDC13, 300 MHz) delta 1.63 (s, 9H), 4.00 (s, 3H), ~-7.61 (d, 2H, J=8.15 Hz), 8.02 (d, 2H, J=8.15 Hz), 8.33 (d, lH, J=2.16 Hz), 8.67 (d, lH, J=2.16 Hz); IR (KBr) 30S0, 3000, 2970, 2210, 1730, 1700, 1600, 1530, 1420, 1360, 1325, 1285, 1255, 1220, 1160, 1060, 845 and 765 cm l; M/S 373 (M +2), 371 (M ), 315, 298, 282 and 256. ~
Anal. Calcd. for C20H18ClNO4: C, 64.60: H, 4.88; Cl, ~;
9.53; N, 3.77.
Found: C, 64.87; H, 4.88; N, 3.77; Cl, 9.58. ;~

Example 4 2-Amino-4-hvdroxy-6-(4-tert.-butoxycarbonyl- ~
phenylethynyl)pyrido[2~3-d]pyrimidine : , l ~
¦ To a solution containing 0.11 9 of sodium in 30 ml ¦; ~ of anhydrous tert.-butanol is added 0.45 9 of guanidine ~ ~ 20 hydrochloride. After stirring the mixture a~ room tem- ~`
l .~ .
perature for lS minutes, 0.35 9 of methyl 5-(4-tert.-butoxycarbonylphenyI)ethynyl-2-chloro-3-pyridine-carboxylate is added in one portion. The mixture is ~- heated under reflux under nitrogen for 4 hours, cooled, 25 diluted with ethanol, and the solvent removed under ;;
reduced pressure. The residue is dissolved in water and filtered to remove a small amount of insoluble material.
The filtrate is acidified with a 3N hydrochloric acid ' l~ ! solution and the precipitate that forms is collected by filtration, washed with water, and dried under reduced pressure to give 0.15 g (44%) of 2-amino-4-hydroxy-6-(4-tert.-butoxycarbonylphenylethynyl)pyridot2,3-d]-pyrimidine as a pale yelIowish solid: m.p. >260~C; NMR
~DMSO-d6, 80 MHz) delta 1.55 (s, 9H), 7.71 (d, 2H, J=8.6 ;
Hz), 7.g6 ~d, 2H, J~8.6 Hz), 8.36 (d, lH, J=2.5 Hz), 8.73 (d, lH, Jz2.5 Hz). ~--, Example S
2-Amino-4-hydroxv-6-(4-carboxyphenyl-ethynyl)Pyridol2l3-d]pyrimidlne Thirty-four milligrams of 2-amino-4-hydroxy-6-(4-tert.-butoxycarbonylphenylethynyl)pyridol2,3-d]-pyrimidine is added to 15 ml of nitromethane which has been saturated with hydrogen chloride gas at 0C. The mixture is stirred for 1 hour. Anhydrous ether is added and the solid filtered to give 27.6 mg (62%) of 2-amino-104-hydroxy-6-~4-carboxyphenylethynyl)pyrido[2,3-dl-pyrimidine as a pale yellowish solid: m.p. >260~C; NMR
(DMSO-d6, 80 MHz) delta 7.71 (d, 2H, J=8.4 Hz), 8.00 (d, 2H, J=8.4 Hz), 8.40 (d, lH, Js2.3 Hz), 8.75 (d, lH, J=2.3 Hz).

15Example 6 2-Pivaloylamino-4-hYdroxy-6-bromodoPyrido- ;
~2,3-d]pyrimidine A mixture of 21.72 9 of 2-amino-4-hydroxy-6-bromo-pyridol2,3-d]pyrimidine in 75 ml of pivalic anhydride is heated under reflux under a nitrogen atmosphere for 3 hours. The dark reaction mixture is cooled and anhydrous ether is added. The solid which forms i8 col-lected by filtration and dissolved in methylene chloride and the solution is filtered through silica gel in a 25 sintered funnel. The silica gel pad is extracted with a !
methanol:methylene chloride mixture. Evaporation of the filtrate gave 13.58 9 (46%) of 6-bromo-2-pivaloyl- `
amino-S-deaza-4(3H)-pteridone as a pale yellowish solid.
~~ This material is sufficiently pure for the next react-ion. A small amount of the solid was recrystallized from benzene: m.p. 258-260C; NMR (CDC13, 300 MHz) delta 1.36 ~s, 9H), 8.33 (br~, lH), 8.65 (d, lH, J-2.65 Hz), 8.92 (d, lH, J=2.65 Hz): IR (KBr) 3250, 3190, 3100, ~ 1670, 1610, 1550, 1480, 1375, 1275, 1220, 1140, 1020, : ; ' , .

950, and 815 cm 1.
Anal. Calcd. for C12H13BrN4O2: C, 17.33; Br, 24.58. ~ ;
Found: C, 44.56; H, 3.85; N, 17.30; Br, 24.38. ~-, ~:
Similarly prepared from the corresponding iodo compound is 2-pivaloylamino-4-hydroxy-6-iodopyrido- -12,3-dlpyrimidine in 54% yield; m.p. 272-273C(CH3CN);
NMR (CDC13, 300 MHz) delta 1.36 (s, 9H), 8.29 ~brs, lH), 8.83 (d, lH, J=2.32 Hz) 9.06 ~d, lH, J=2.32 Hz); IR
(KBr) 3240, 3200, 3120, 2970, 1670, 1610, 1580, 1545, 1480, 1430, 1370, 1325, 12~0, 1230, 1140, 1020, 950, ,~
810, and 760 cm 1. ``

Analogously, a mixture of 0.52 9 of 2-amino-4-hydroxy-6-iodopyridol2,3-d]pyrimidine and 0.03 9 of ;-15 4-dimethylaminopyridine in 10 ml of acetic anhydride is i heated under reflux under nitrogen for 3 hours. After cooling the reaction mixture to room temperature, ~-anhydrous ether is added, and the reaction mixture fil-tered to give 0.52 9 (87~) of 2-acetamido-4-hydroxy-6-20 iodopyridol2,3-d]pyrimidine as a tan colored solid: ~-m.p.>280C: NMR ~DMSO-d6, 80 MHz) delta 2.18 (s, 3~), 8.67 ~d, lH, J=2.5 Hz), 9.02 (d, lH, J=2.5 Hz): M/S 330 (M ), 315 and 288. -Example 7 Diethyl N-~4-ethynylbenzoyl)-L-glutamate -~
~ To a solution of 0.55 9 of 4-ethynylbenzoic acid ~;
;~ ~obtained from tert.-butyl 4-ethynylbenzoate in 84%
yield by hydrolysis with trifluoroacetic acid) in 50 ml of anhydrous ether and 25 ml of anhydrous tetrahydro-furan is added 1.58 ml of triethylamine. This is followed by l.00 9 of phenyl N-phenylphosphoramido- ~, chloridate. After stirring the reaction mixture at room ~- ~ temperature under nitrogen for 0.5 hour, 0.90 9 of ~ 1332169 diethyl L-glutamate is added in one portion. ~he mix-ture is allowed to stir for another 8 hrs. After a workup, the residue is subjected to column chroma-tography using a 1% methanol:methylene chloride mixture S as the eluent. The major fraction isolated from the I column contained 0.68 9 (54~) of diethyl N-(ethynyl-benzoyl)-L-glutamate as an oil which slowly solidified:
NMR (CDC13, 300 MHz) delta 1.25 (t, 3H, J=6.9 Hz), 1.33 (t, 3H, J~6.9 Hz), 2.11-2.60 (m, 4H), 3.23 (s, lH), 4.09 10 (q, 2H, J=6.9 Hz), 4.27 (1, 2H, J-6.9 Hz), 4.80 (m, lH), 7.12 ~d, lH, J=7.2 Hz), 7.59 td, 2H, J=8.4 Hz), 7.81 (d, 2H, J-8.4 Hz); IR (KBr) 3330, 3280, 2990, 1735, 1640, 1520, 1380, 1200, 1105, 1020, 855, and 770 cm 1.

ExamPle 8 Diethyl N-14-(2-pivaloylamino-4-hydroxypyrido-[2,3-d]pYrimidin-6-ylethvnyl)benzoyl]-L-glutamate ~;~
,~
A mixture of 2.0 g of 6-bromo-2-pivaloylamino-- 4-hydroxypyridol2,3-d]pyrimidine, 2.1 9 of diethyl ,~ . .
N-(4-ethynylbenzoyl)-L-glutamate, 2.57 ml of triethyl-; 20 amine, 0.11 9 of palladium chloride, 0,32 9 of tri--~ phenylphosphine, and 0.05 9 of cuprous chloride in 150 r ml of acetonitrile is heated at reflux under nitrogen for 2.5 hours~ The solid which forms upon first cooling to room temperature is collected by filtration, and washed with cold acetonitrile to yield 1.91 9 of diethyl ; N-[4-(2-pivaloylamino-4-hydroxypyrido[2,3-dlpyrimidin-6-ylethynyl)benzoyl~-L-glutamate which is sufficiently ~ pure for further processing. Chromatography on silica -~
`~ gel with 5~ met~hanol:methylene chloride showing the 30 following physical properties. m.p. >250C NMR (CDC13, 300 MHz) delta 1.25 (t, 3H, J=7.20 Hz), 1.33 ~t, 3H, J=7.20 Hz), 1.36 (s, 9H), 2.14-2.62 (m, 4H), 4.14 (~
2H, J=7.20 Hz), 4.27 ~g, 2H, J-7.20 Hz) 4.79-4.86 ~m, lH), 7.30 ~d, lH, J=8.40 Hz), 7.63 ~d, 2H, J=8.25 Hz), 35 7.86 ~d, 2H, J=8.25 Hz), 8.51 (brs, lH), 8.64 (d, lH, '` '~;

, . . , ,"; ''~ ' ~ 1332169 ~::

J=2.40 Hz), 8.97 (d, lH, J=2.40 Hz), 12.2 ~brs, lH); IR
(KBr) 3330, 3290, 2970, 1730, 1655, lS90, 1530, 1440, 1370, 1260, 1140, 1020, 965, 925, 850, 810, and ~60 cm l; 13C-NMR (CDC13, 75 MHz) delta 14.3, 27.1, 27.2, 30.7, 40.6, 52.7, 61.1, 62.0, 87.61, 92.71, 115.1, 117.3, 125.9, 127.4, 127.5, 132.0, 133.9, 138.7, 149.6, 157.8, 158.6, 160.5, 166.4 172.1, 173.5, 180.8.
Anal- Calcd- for C30H33N57 C~ 62-60; H~ 5-78; N~
12.35.
Found: C, 44.56; H, 3.85; N, 17.30; Br, 24.38. ~;
.
Example 9 2-Pival~ylamino-4-hv_roxY-6-ethynylpYrido-2,3_d]Pyrimidine ; ;, ':`, ~.' To a solution of 1.47 9 of 2-pivaloylamino-4-hydroxy-6^trimethylsilylethynylpyridol2,3-d]pyrimidine in 100 ml of anhydrous tetrahydrofuran are added, under nitrogen and at 0C, 4.75 ml of lM tetrabutylammonium ~;
;~ fluoride in tetrahydrofuran. After 5 minutes, the ~-~
reaction mixture is allowed to warm to room temperature ~- 20 and then is stirred for 2 hours. The solvent is removed under reduced pressure and the residue passed through a ~
small pad of si}ica gel eluting with a 1% methanol: ;
methylene~chlorid~e solution. The filtrate is concen-trate~d under reduced pressure~ and the residue purified further by radial chromatography on sllica gel. The major fracti~on isolated from the plate contained 1.20 9 (100%) of 2-pivaloylamino-4-hydroxy-6-ethynylpyrido-t2,3-d]pyrimidine as an off white solid: m.p. >250C;
' NMR (CDC13, 300 MHz) delta 1.36 (s, 9H), 3.31 ~s, lH), 8.39 ~brs, lH), 8.60 ~d, iH, J=l.99 Hz), 8.49 ~d, lH, J~1.99~Hz); IR ~KBr) 3304, 3200, 2980, 1670, 1620, 1550, 470, 1445, 1380, 13~5, 12B0, 1240, 1140, 1025, and 970 cm . ! ;;

, ~
,~
,` :, ~'~

~332169 2-Pivaloylamino-4-hydroxy-6-trimethylsilylethynyl-pyridol2,3-d]pyrimidine is prepared in 81% yield from 2-pivaloylamino-2-hydroxy-6-bromopyridol2,3-d]pyrimidine and trimethylsilylacetylene analogously to Example 2B.
m.p. >250C; NMR ~CDC13, 300 MHz) delta 0.29 ls, 9H), 1~35 (s, 9H), 8.36 (brs, lH), 8.57 (d, lH, J=2.45 Hz), 8.92 (d, lH, J=2.45 Hz); IR (KBr) 3200, 2970, 2170, 1680, 1620, 1545, 1475, 1440, 13~0, 1275, 1250, 1145, 930, and 845 cm 1.

Example 10 Diethyl N-(4-bromobenzoyl)-L-glutamate To a mixture of 0.92 9 of of 4-bromobenzoyl chloride and 1.0 9 of diethyl L-glutamate in 50 ml to dry methylene chloride is added 1.16 ml of triethyl-amine. The reaction mixture is stirred overnight under nitrogen. After a standard workup, the methylene chloride solution is concentrated under reduced pres-sure, and the residue recrystallized from hexanes to give 0.68 9 (46~) of analytically pure diethyl N-(4- ~
20 bromobenzoyl)-L-glutamate as a white solid: m.p. ~--`
82.5-83.5C; NMR (CDC13, 300 MHz) delta 1.26 (t, 3H, J=6.9 Hz), 1.33 (t, 3H, J-6.9 Hz), 2.11-2.60 (m, 4H), -~ 4.14 ~g, 2H, Js6.9 Hz), 4.27 ~, 2H, J=6.9 Hz) 4.78 (m, lH), 7.14 (d, lH, J=7.2 Hz), 7.61 (d, 2H, J-~.4 Hz), 2~5 7.~73-(d, 2H, J-8.4 Hz); IR (KBrj 3320, 2980, 1745, 1720, 1635, 1520, 1375, 1300, and 1200 cm ;
Anal. Calcd. for C16H20BrNO5: C, 49.75; H, 5.22; N, ;~
3.63; Br, 20.69.
Found: C, 49.70; H, 5.15; N, 3.65; Br, 20.90. 1 ;

DiethyI N-~4-iodobenzoyl)-L-glutamate is prepared from 4-iodobenzoyl chloride and diethyl L-glutamate in 56% yield by the same method. m.p. 105-106C; NMR
`~ (CDC13, 300 MHz) delta 1.26 ~t, 3H, J=7.2 Hz), 1.33 (t, ~ 3H, J=7.2 Hz), 2.11-2.60 ~m, 4H), 4.14 (~, 2H, J=7.2 -`' ' ~ ~ "" '.

;~

1332169 ~
~-.` ................................................................. . ~ -22-Hz), 4.78 (m, lH), 7.15 (d, lH, J=7.2 Hz), 7.58 (d, 2H, J=8.4 Hz), 7.83 (d, 2H, J-8.4 HZ) ,: . .
Example 11 Diethyl N-4-(2-pivaloylamino-4-hydroxYPyri~o-S l2,3-d~pyrimidine-6-ylethvn~l)benzoyl-L-clutamate A mixture of 0.68 9 of 2-pivaloylamino-4-hydroxy-6-ethynylpyridol2,3-d]pyrimidine, 1.20 9 of diethyl N-(4-~ iodobenzoyl)-L-glutamate, 0.35 ml of triethylamine, 0.04 `~ g of palladium chloride, 0.139 of triphenylphosphine, ~; 10 and 0.02 9 of cuprous iodide in 75 ml of acetonitrile is heated at reflux under nitrogen for 3.5 hours. The re- ~
action mixture is cooled and the solid collected, tri- ~ -turated with ethyl acetate, and filtered. The solid is recrystallized from ethanol to yield diethyl N-4-(2- ~
~ 15 pivaloylamino-4-hydroxypyrido[2,3-dlpyrimidin-6-yl- ~;
'~3,.`,~ ethynyl)benzoyl-L-glutamate. m.p. ~250C; NM~ ~CDC13, ; ~ 300 MHz) delta 1.~25 (t, 3H, J~7~.20 Hz), 1.33 (t, 3H, J-7.20 Hz), 1.36 (s, 9H), 2.}4-2.62 (m, 4H), 4.14 (~
; ; 2H, J-7.20 Hz);, 4.27~ (g, 2H, J~7.20 Hz) 4.79-4.86 (m, ~lH), 7.30 (d, lH, J~8.40 Hz), 7.63 (d, 2H, J-8.25 Hz), ;~
7.~86 (d~,~2H, J~8.25~Hz), 8.51 (brs, lH), 8.64 (d, lH~
J~2.40 Hz), 8~.97 (d, lH, J-2.40 Hz), 12.2 tbrs, lH): IR
KBr~)~ 3330~ 3290,~ 2970,;1730, 1655, 1590, 1530, 1440, 1370,~ 1260,~1140,~1020, 965, 925, 850, 810, and 760 2~5~ CD ~ 3C-NMR~(CDC13,~75 MH~z) delta 14.3, 27.1, 27.2, 30.~7, 40.6, 52.7~,~61.1~, 62.0, B7.61, 92.71, 115.i, 117.3,~125.9, 127.4,~ 127.5, 132.0, 133.9, 13B.7, 149.6, 157.8, I58.6, 160.5, I66.4 172.1, 173.5, 180.8.
Anal. Calcd. for C30H33N5O7: C, 62.60; H, 5.78; N, ;~!~
ou~d.~C, 4~.56: N, 3.85: N, 17.30: Dr, 24.38.

, ~
, ~
~ S~

13~6~

ExamPle 12 2-Pivaloylamino-4-hydroxy-6-~4-tert.-butoxy-carbonylphenylethynyl)pyrido[2,3-d~Pyrimidine A mixture of 2.0 9 of 2-pivaloylamino-4-hyd~oxy-5 6-bromopyrido~2,3-d]pyrimidine ~prepared according to -Example 6), 1.31 9 of tert.-butyl 4-ethynylbenzoate, 2.57 ml of triethylamine, 0.11 9 of palladium chloride,;~
0.32 9 of triphenylphosphine, and O.OS g of cuprous iodide in lS0 ml of acetonitrile is heated at reflux -~
under nitrogen for 2.5 hours. The reaction mixture is cooled to room temperature and then in an ice bath. The solid is collected and washed with small portions of cold acetonitrile to yield 1.91 9 ~69~) of 2-pivaloyl-amino-4-hydroxy-6-(4-tert.-butoxycarbonylphenylethynyl)-1~ pyrido[2,3-dlpyrimidine as a pale yellowish powder, which is sufficiently pure for the next reaction. A
small sample of this solid, purified further by chroma- ~-tography on silica gel using a 5% methanol:methylene chloride mixture as the eluent, had the following con~
stants: m.p. >250C; NMR (CDC13, 300 MHz) delta 1.37 (s, 9H), 1.63~(s,~9H), 7.61 (d, 2H, Jz8.50 Hz), 8.02 (d, 2H, ~;~
J-8.50 Hz), ~8.42~(brs, 1H), 8.66 (slightly brs, 9~.01 -slight}y brs, lHj;IR ~KBr) 3200, 2980, 1710, 1670, ;`
16;00,~1545, 1~440,~ 1375, 1290, 1140, and 770 cm 1.

2~5~ Al~te~rnatively, a;mixture of 0.15 9 of 2-pivaloyl~
amino-4-hydroxy-6-ethynylpyridol2,3-d]pyrimidine, 0.16 9 of-tert.~-butyl 4-bromobenzoate, 0.23 ml of triethyl~
amine, 0.01 9 of palladium chloride, 0.03 9 of tri~
pbeny1phosphine, and~0.01 9 ~of cuprous iodide in 20~ml 3~Q~ o~;ace~tonltrile~ s~heated at ref}ux under nitrogen for 4 -;~
hours. Upon cooling, the~reaction mixture is filtered `~
;to~give 0.118~g~of a brown solid, which is further puri-f~ied~by~radlal chromatog;raphy using a 5% methanol:
methylene ch~loride solution~as the eluent. The major .,~,t~ 35 fraction isoldted from the plate contained a yellowish ~`~

, I
:~
~:~

solid which was triturated with ethyl acetate to give 0.1 9 (40~) of 2-pivaloylamino-4-hydroxy-6-t4-tert.-butoxycarbonylphenylethynyl)pyridol2,3-d]pyrimidine, constants as above.

Example 13 2-PivaloYl-4-hydroxy-6-(4-carboxyphenyl-ethynyl)Pyrldol2~3-d]pyrimidine ~; One gram of 2 pivaloylamino-4-hydroxy-6-(4-tert.-butoxycarbonylphenylethynyl)pyridol2,3-d]pyrimidine is added to 25 ml of nitromethane saturated with hydrogen chloride gas at 0C. After stirring at 0~C, the reaction mixture is allowed to reach room temperature and stirred for an additional hour. The suspension is ~-diluted with anhydrous ether and suction filtered. The collected solid is washed with ether, methanol, and ether again, and then dried under reduced pressure to ~
;~ give 0.81 9 of 2-pivaloyl-4-hydroxy-6-(4-carboxyphenyl- ~;
ethynyl)pyridot2,3-d]pyrimidine as a yellowish powder~
m.p. ~250C; NMR (CDC13, 300 MHz) delta 1.25 (s, 9H), 7.72 (d, 2H,~3~8.02 Hz), 7.98 (d, 2H, J=8.02 Hz), 8.52 ~;
d,~lH, J~2.01~Hz?, 9.01 (d, lH, J-2.01 Hz); IR (KBr) 3~20,~3000,~1725, 1680, 1425, 1405, 1360, 1250, 1130, 10~20, and 800 cm 1.

Alternati~vely, 2-amino-4-hydroxy-6-1(4-carboxy- ~-25~ phenyl)~ethynyl~lpyrido[2,~3-d]pyrimidine, prepared as described in Example 5, is heated in refluxing pivalic anhydrideiaccording to the procedure of Example 6 to ;~
yield 2-pivaloyl-4-hyd~roxy-6-1(4-carboxyphenyl)ethynyl]-pyridol2,3-d]pyr~lmidine. ;~

,`'' ~
.

1332169 ~

Example 14 Diethyl N-4-(2-pivaloylamino-4-hydroxypyrido-[2~3-d]pyrimidine-6-ylethynyl)benzoyl-L-glutamate To a solution of 0.09 9 of diethyl N-(4-2-2-5 pivaloyl-4-hydroxy-6-(4-carboxyphenylethynyl)pyrido-12,3-d]Pyrimidine and 0.07 ml of N-methylmorpholine in 5 ml of dry N-methylpyrrolidone is added 0.09 g of phenyl ~-phenylphosphoramidochloridate. After stirring the reaction mixture at room temperature under a nitrogen atmosphere for 20 minutes, 0.08 9 of diethyl L-glutamate hydrochloride is added and the mixture stirred for ~-~
another 24 hours. The solvent is removed by distilla-ion under reduced pressure and the residue is par-titioned between chloroform and water. The orsanic 15 phase is dried over anhydrous sodium sulfate and con- ~-centrated under reduced pressure. The residue is ~` ~subj~ected to repeated chromatography on silica gel using ~ -a 2% methanol:methylene chloride mixture as the eluent.
The major fraction isolated contained 0.05 9 ~38~) of ; 20 diethyl N-4-(2-pivaloylamino-4-hydroxypyridol2,3-d]- ~-pyrimidine-6-ylethynyl)benzoyl-L-glutamate which has a -m.p.~ >250C, constants as reported in Examples 8 and 11.

Die~hvl N-~(4-12-~2-~ivaloylamino-4-hydroxy-~5,6,7,8-tetrahydroPyrido[2~3-d]pyrimidin-6 ethvl]benzovl)-L-qlutamate A mixture of 0.59 9 of diethyl N-l4-(2-pivaloyl-amino-4-hydroxypyridol2,3-d]pyrimidin-6-ylethynyl)- `~
benzoyl]-L-glutama~t~o and 1.5 9 of 55 palladium on char- ~-30 coa~1 in 30 ml of trifluoroacetic acid is hydrogenated at .'`i~
53~psi at room temperature for 24.5 hoursO ~he reaction mixturé is~diluted with methylene chloride and filtered thr~ough Celite. The solvent is removed under reduced pressure. ~he roslduo is redissolved in methylene -~

13~169 chloride and extracted with a saturated sodium bicarbon-ate solution and dried over anhydrous sodium sulfate.
The solvent is removed under reduced pressure and the residue chromatographed on silica gel using a 4%
S methanol:methylene chloride mixture as the eluent.
Evaporation of the eluate yields 0.60 9 (100%) of diethyl N-(4-[2-(2-pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyridol2,3-dlpyrimidin-6-yl)ethylJbenzoyl)-L-glutamate as a white solid: m.p. >250C; NMR (CDC13, 10 300 MHz) delta 1.22 ~t, 3H, J=7.20 Hz), 1.29 (s, 9H), 1.30 (t, 3H, J=7.20 Hz), 1.61-3.35 (m, 13 H), 4.11 (~, 2H, J=7.20 Hz), 4.23 (~, 2H, J=7.20 Hz), 4.77-4.84 (m, lH), 5.15 ~brs, lH), 7.17 (d, lH, J=7.50 Hz), 7.23 (d, 2H, J=8.10 Hz), 8.56 (brs, lH); IR (KBr) 3400, 3280, 15 2980, 1735, 1630, ~570, 1460, 1390, 1350, 1310, 1200, 1155, 1025, 930, and 800 cm 1.
Anal. Calcd. for C30H37N50~: C, 61.73; H, 7.08; N, 12.00.
Found: C, 44.56: H, 3.85; N, 17.30; Br, 24.38.
~ .
Example 16 N-(4-[2-(2-amino-4-hydroxY-S,6,7,8-tetrahydropyridol2~3-dlPyrimidin-6-yl) ethyl]benzoyl)-L-glutamatic acid A solution containing 0.53 g of diethyl N-(4- -25 12-(2-pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyrido-[2~3-d]pyrimidin-6-yl)ethyl]benzoyl)-L-glutamate~ 3 ml of a lN sodium hydroxide solution in 50 ml of methanol is stirred at room temperature for 70 hours. The mix-ture is acidified with acetic acid and the solid which ..~
forms is filtered, washed with methanol, and dried under ` reduced pressure to give 0.20 g (50%) of the known ; N-(4-[2-(2-amino-4-hydroxy-S,6,7,8-tetrahydropyrido-2~3-d]pyrimidin-6-yl)ethyl]benzoyl)-L-glutamatic acid.

;' ~` , :

Claims (19)

1. In the process of preparing a compound of the formula:

wherein R1 is -NHCH(COOR2)CH2CH2COOR2 or OR2;
R2 is hydrogen or a carboxylic acid protecting group:
R4 is hydrogen or an amino protecting group;
Z1 when taken independently of Z2 is hydrogen; and Z2 when taken independently of Z1 is hydrogen, methyl or ethyl; or Z1 and Z2 when taken together are a carbon-carbon bond;
the step of allowing an unsaturated compound to react with a haloaromatic compound in the presence of a palladium catalyst, said unsaturated compound and said haloaromatic compound being selected such that said haloaromatic compound is (i) a pyridine of the formula:

wherein Y is amino or a nucleofuge;
X is bromo or iodo; and R3 is alkyl of 1 to 4 carbon atoms; or (ii) a fused pyridine of the formula:

wherein R4 is as defined above;
X is bromo or iodo; and said unsaturated compound is of the formula:

wherein Z1, Z2, R1, and R2 are as defined above with the proviso that when the haloaromatic compound is a pyridine of the formula (i), the reaction product of said pyridine and said unsaturated compound is further reacted with guanidine.

2. The process according to claim 1 wherein the haloaromatic compound is a fused pyridine of the formula:

wherein R4 is hydrogen or an amino protecting group and X is bromo or iodo; and said palladium catalyst is generated from a triarylphosphine, a palladium halide salt, and a cuprous halide salt.

3. The process which comprises (1) allowing a haloaromatic compound of the formula:

wherein R4 is hydrogen or an amino protecting group and X is bromo or iodo; and to reach with an unsaturated compound of the formula:

wherein Z1 when taken independently of Z2 is hydrogen;
Z2 when taken independently of Z1 is hydrogen, or Z1 and Z2 when taken together are a carbon-carbon bond and R2 is a carboxylic acid protecting group, in the presence of a palladium catalyst, to yield an unsaturated compound of the formula:

and (2) catalytically hydrogenating said unsaturated compound to yield a protected derivative of 2-amino-4-h y d r o x y - 5, 6, 7, 8, - t e t r a h y d r o - 6 - [ 2 - ( 4 -carboxyphenyl)ethyl]pyrido[2,3-d]pyrimidine of the formula:

in which R2, R3 and Z2 are as defined above.

4. The process according to claim 3 which comprises removing said protecting groups to yield 2-amino-4-hydroxy-5,6,7,8-tetrahydro-6-[2-(4-carboxyphenyl)ethyl]
pyrido[2,3-d]pyrimidine.

5. 2-Amino-4-hydroxy-5,6,7,8,-tetrahydro-6-[2-(4-carboxyphenyl)ethyl]pyrido[2,3-d]pyrimidine.

6. The process according to claim 2 in which R1 is OR2, and R2 contains a chiral center and is in one chiral form substantially free of the other.

7. The process according to claim 2 wherein R1 is alkoxy or 1 to 10 carbon atoms.

8. The process according to claim 7 wherein R1 is tert.-butoxy.

9. The process according to claim 7 wherein R4 is alkanoyl of 2 to 10 carbon atoms inclusive of the carbonyl carbon atom.

10. The process according to claim 9 wherein R4 is pivaloyl.

11. The process according to claim 2 in which a 2-alkamido-4-hydroxy-6-iodopyrido[2,3-d]pyrimidine is allowed to react with a dialkyl ester of N-(4-ethynyl-benzoyl)-L-glutamic acid.

12. The process according to claim 2 in which a 2-alkamido-4-hydroxy-6-bromopyrido[2,3-d]pyrimidine is allowed to react with a dialkyl ester of N-(4-ethynyl-benzoyl)-L-glutamic acid.

13. The process according to claim 2 wherein the reaction is conducted in acetonitrile as a solvent.

14. The process according to claim 1 wherein the haloaromatic compound is a pyridine of the formula:

wherein Y is amino or a nucleofuge;
X is bromo or iodo; and R3 is alkyl of 1 to 4 carbon atoms; said unsaturated compound is of the formula:

wherein Z1 when taken independently of Z2 is hydrogen;
Z2 when taken independently of Z1 is hydrogen, methyl or ethyl; or Z1 and R2 when taken together are a carbon-carbon bond;
R1 is -NHCH(COOR2)CH2CH2COOR2 or OR2: and R2 is a carboxylic acid protecting group; and said palladium catalyst is generated from a triarylphosphine, a palladium halide salt, and a cuprous halide salt.

15. A process according to claim 14 wherein R1 is alkoxy of 1 to 10 carbon atoms and Y is chloro, bromo, iodo, an aryl or alkylsulfinyl or -sulfonyl group of up to 10 carbon atoms, an arylthio or alkylthio group of up to 10 carbon atoms, mercapto, or alkoxy of up to 10 carbon atoms.

16. A process according to claim 15 wherein R3 is methyl and Y is chloro.

17. The process according to claim 14 in which R1 is OR2, and R2 contains a chiral center and is in one chiral form substantially free of the other.

18. The process according to claim 14 wherein R1 is alkoxy of 1 to 10 carbon atoms.

19. The process according to claim 18 wherein R1 is tert.-butoxy.