WO1997049705A1

WO1997049705A1 - 5,6,7,8-TETRAHYDROPYRIDO[2,3-d]PYRIMIDINE DERIVATIVES

Info

Publication number: WO1997049705A1
Application number: PCT/US1997/010952
Authority: WO
Inventors: Edward C. Taylor; Paul Gillespie
Original assignee: The Trustees Of Princeton University
Priority date: 1996-06-25
Filing date: 1997-06-24
Publication date: 1997-12-31
Also published as: AU3500997A

Abstract

Glutamic acid derivatives in which the amino group is substituted with a 2-amino-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-ylalkyl-Z-carbonyl group, in which Z is pyridinediyl in which the valence bonds originate from nonadjacent carbon atoms of the ring, are antineoplastic agents. A typical embodiment is N-{3-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)ethyl]-pyridin-5-ylcarbonyl}-L-glutamic acid.

Description

5,6,7_yH-TETRAHYDROPYRIDO[2,3-d]PYRIMIDINE DERIVA TIVES

This invention relates to 5,6,7,8-tetrahydropyridof2,3-t7]pyrimidines of the formula:

in which

R is hydroxy or amino;

R is hydroxy or a carboxylic acid protecting group;

R is hydrogen or an amino protecting group; Z is pyridinediyl in which the valence bonds originate from nonadjacent carbon atoms of the ring; and n has a value of 2 or 3.

The present invention also pertains to the pharmaceutically acceptable salts of the 5,6,7,8-tetrahydropyrido[2,3-tf]pyrimidines of Formula I. In addition, the invention pertains to a method of inhibiting neoplastic growth in a mammal in which the growth is dependent on folic acid, or a metabolic derivative of folic acid (such as N⁵,N -methylenetetrahydrofolate), as a substrate. The method comprises administering, in a single or multiple dose regimen, an effective amount of a compound according to Formula I to a mammal in need of such therapy. Finally, the invention pertains to pharmaceutical compositions for inhibiting such neoplastic growth in a mammal through inhibition of folate enzymes which comprises a compound according to Formula I in combination with a pharmaceutically accept¬ able carrier.

The compounds of Formula I are named herein as derivatives of the pyrido[2,3- djpyrimidine fused ring system which is numbered as follows: ^O

^O 8

It will be appreciated that the pyrido[2,3-d]pyrimidines of Formula I are the tautomeric equivalent of the corresponding 3-H-4-oxo or 3-H-4-imino structures. For simplicity's sake, the compounds are depicted herein as 4-hydroxy and 4-amino com- pounds, it being understood the corresponding and tautomeric keto and imino struc¬ tures, respectively, are fully equivalent; e.g. :

The compounds of Formula I can be employed in the form of the free dicarbox- ylic acid, in which case both R groups are OH (hydroxy). Alternatively, the compounds often can be employed in the form of a pharmaceutically acceptable salt, in which case the hydrogen atom when R is hydroxy is replaced by a pharmaceuti¬ cally acceptable cation. Such salt forms, including hydrates thereof, are often crystal¬ line and advantageous for forming solutions or formulating pharmaceutical composi¬ tions. Pharmaceutically acceptable salts with bases include those formed from the alkali metals, alkaline earth metals, non-toxic metals, ammonium, and mono-, di- and trisubstituted amines, such as for example the sodium, potassium, lithium, calcium, magnesium, aluminum, zinc, ammonium, trimethylammonium, triethanolammonium. pyridinium, and substituted pyridinium salts. The mono and disodium salts, particu¬ larly the disodium salt, are advantageous. In addition to the center of chirality about the carbon atom on the glutamic acid designated *, a second chiral center is present in the 6-position of the 5,6,7.8-tetrahy- dropyrido[2,3-d]pyrimidine ring system. Both the therapeutically active diastereo- meric mixtures and the individual diastereomers are included in the scope of this - 3 -

invention. When both individual diastereomers are formed, they can be separated mechanically as by chromatography or chemically by forming salts with a chiral acid, such as the individual enantiomers of 10-camphorsulfonic acid, camphoric acid, alpha-bromocamphoric acid, tartaric acid, diacetyltartaric acid, malic acid, pyrrolidone-5-carboxylic acid, and the like, and then freeing one or both of the indi¬ vidual diastereomeric bases, optionally repeating the process, so as obtain either or both substantially free of the other; i.e., in a form having an optical purity of >95%.

The protecting groups designated by R and R utilized herein denote groups which generally are not found in the final therapeutic compounds but which are inten- tionally introduced at some stage of the synthesis in order to protect groups which otherwise might be altered in the course of chemical manipulations. Such protecting groups are removed at a later stage of the synthesis and compounds bearing such pro¬ tecting groups thus are of importance primarily as chemical intermediates (although some derivatives also exhibit biological activity). Accordingly the precise structure of the protecting group is not critical. Numerous reactions for the formation and removal of such protecting groups are described in a number of standard works including, for example, "Protective Groups in Organic Chemistry", Plenum Press, London and New York, 1973; Greene, Th. W. "Protective Groups in Organic Synthesis". Wiley, New York, 1981 ; "The Peptides", Vol. I, Schroder and Lubke, Academic Press, London and New York, 1965; "Methoden der organischen Chemie", Houben-Weyl, 4th Edition, Vol.15/1, Georg Thieme Verlag, Stuttgart 1974, the disclosures of which are incorporated herein by reference.

With respect to R²' a carboxy group can be protected as an ester group which is selectively removable under sufficiently mild conditions not to disrupt the desired structure of the molecule, especially a lower alkyl ester of 1 to 12 carbon atoms such as methyl or ethyl and particularly one which is branched at the 1 - or α position such as t-butyl; and such lower alkyl ester substituted in the 1- or 2-position with (/) lower alkoxy, such as for example, methoxymethyl, 1-methoxyethyl, and ethoxymethyl, (//) lower alkylthio, such as for example methylthiomethyl and 1-ethylthioethyl; (Hi) halogen, such as 2,2,2-trichloroethyl, 2-bromoethyl, and 2-iodoethoxycarbonyl; (z^'v) one or two phenyl groups each of which can be unsubstituted or mono-, di- or tri- substituted with, for example lower alkyl such as tert.-butyl, lower alkoxy such as methoxy. hydroxy, halo such as chloro, and nitro, such as for example, benzyl, 4- nitrobenzyl, diphenylmethyl, di-(4-methoxyphenyl)methyl; or (v) aroyl, such as phen- acyl. A carboxy group also can be protected in the form of an organic silyl group such as trimethylsilylethyl or tri-lower alkylsilyl, as for example tri-methylsilyloxy- carbonyl.

With respect to R³, an amino group can be protected as an amide utilizing an acyl group which is selectively removable under mild conditions, especially formyl, a lower alkanoyl group which is branched in 1- or α position to the carbonyl group, particularly tertiary alkanoyl such as pivaloyl, or a lower alkanoyl group which is substituted in the position α to the carbonyl group, as for example trifiuoroacetyl.

In the compounds of Formula I, Z is pyridinediyl. The depicted valence bonds of Z originate from nonadjacent carbon atoms of the ring. Z thus can be, for example, pyridine-2,4-diyl, pyridine-2,5-diyl, pyridine-2,6-diyl, or pyridine-3,5-diyl. It will be appreciated that when the divalent group comprised by Z is asymmetric, as for exam¬ ple pyridine-2,5-diyl (as contrasted with the symmetrical pyridine-2,6-diyl), the single group can be oriented in either of two ways; e.g., (i) with the -C_nH_2n- group depicted in Formula I in the 2-position and the carbonyl group in the 5- position, or (ii) with the carbonyl group in the 2-position and the -C_nH_2n- group in the 5- position

1 7

Particularly preferred compounds are those wherein R and R are both hydroxy, R is hydrogen, and n has a value of 2; e.g., N-{2-f2-(2-amino-4-hydroxy-5,6,7,8- tetrahydropyrido[2,3-dJpyrimidin-6-yl)ethyl]-pyridin-4-ylcarbonyl}-L-glutamic acid; N-{2-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)ethyl]- pyridin-5-ylcarbonyl}-L-glutamic acid; N-{2-[2-(2-amino-4-hydroxy-5,6,7,8-tetra- hydropyrido[2,3-d]pyrimidin-6-yl)ethyl]-pyridin-6-ylcarbonyl } -L-glutamic acid; N- {4-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-dJpyrimidin-6-yl)ethyl]- pyridin-2-ylcarbonyl} -L-glutamic acid; N-{5-^r2-(2-amino-4-hydroxy-5,6,7,8-tetra- hydropyrido[2,3-d]pyrimidin-6-yl)ethyl]-pyridin-2-ylcarbonyl}-L-glutamic acid; and N-{3-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyridof2,3-d]pyrimidin-6-yl)ethyl]- pyridin-5-ylcarbonyl} -L-glutamic acid.

The compounds of this invention can be prepared through catalytic hydrogenation of a compound of the formula:

II in which:

Z is as defined above;

R^2" is a carboxylic acid protecting group or HC(COR²)CII₉CH₉COR² in which R is a carboxylic acid protecting group; R 3' is an amino protecting group; and each Y when taken separately is hydrogen or both Y's when taken together are a carbon-carbon bond.

Suitable hydrogenation catalysts include noble metals and noble metal oxides such as palladium or platinum oxide, rhodium oxide, and the foregoing on a support such as carbon or calcium oxide.

The protecting groups encompassed by R , R , R , and R^" can be removed following hydrogenation through acidic or basic hydrolysis, as for example with sodium hydroxide, thereby yielding the compounds of Formula I. Methods of remov¬ ing the various protective groups are described in the standard references noted above and incorporated herein by reference.

Compounds of Formula II can be prepared utilizing procedures analogous to those described in U.S. Patent No. 4,818,819, the disclosure of which is incorporated herein by reference. In one embodiment a 6-vinyl- or 6-ethynylpyrido[2,3- djpyrimidine is allowed to react with a halo-Z-carbonyl compound in the presence of a palladium/trisubstituted phosphine catalyst:

in which each of R , R , Y, and Z is as defined above and X is chloro, bromo, or iodo. The 6-vinyl- and 6-ethynylpyrido[2,3-d]pyrimidine intermediates are known chemical intermediates being described, for example, in U.S. Patent No. 4,818,819, noted supra. Alternatively, a 6-halopyrido[2,3-d]pyrimidine intermediate is allowed to react with a vinyl or ethynyl derivative of the pyridinedinyl comprised by Z, again the pres¬ ence of the same palladium/trisubstituted phosphine catalyst:

^{£ c r}

2" V in which each of R , R^' , Y, X, and Z is as defined above. Both the 6-bromo- or 6- iodopyrido[2,3-d]pyrimidine intermediates and palladium/trisubstituted phosphine catalyst again are described in U.S. Patent No. 4,818,819, noted supra.

When R^2" is -CONHCH(COR^2')CH₂CH₂COR^2', the product of this coupling reaction is hydrogenated as described above, and any protecting group removed, as also described above. If on the other hand R is a carboxylic acid protecting group, the R protecting group can removed following hydrogenation as described above, and the resulting free carboxylic acid then coupled with a protected glutamic acid derivative in the manner described in U.S. Patent No. 4,684,653, the disclosure of which is incorporated herein by reference, using conventional condensation tech- niqucs for forming peptide bonds such as dicyclohexylcarbodiimide or diphenyl- chlorophosphonatc. Following this coupling reaction, any remaining protecting groups are removed as discussed below.

According to the foregoing processes, compounds of Formula II in which R is - hydroxy are obtained. When a compound of Formula 1 in which R is amino is desired, a compound in which R is hydroxy can be treated with 1 ,2,4-triazole and (4- chlorophenyl)dichlorophosphate and the product of this reaction then treated with concentrated ammonia.

The pyridinedinyl intermediates either are known or can be made from the known halopicolinic and halonicotinic acids. For example, a halopicolinic or halonicotinic acid can be treated with thionyl chloride and then reacted with dimethyl glutamate to yield a dimethyl halopyridinylcarboxyglutamate. Reaction with trimethylsilylacet- ylene yields the corresponding dimethyl ethynylpyridinylcarboxyglutamate interme- diate which, after removal of the trimethylsilyl protecting group, can be coupled with a 6- halopyrido[2,3-<i]pyrimidine as described above. Alternatively, the dimethyl halopyridinylcarboxyglutamate is allowed to react with a 6-ethynylpyrido[2,3- tfjpyrimidine or 6-vinylpyrido[2,3-t/|pyrimidine. As noted above, 6-ethynyl-, 6- vinyl-, and 6-halopyrido[2,3-t/)pyrimidine intermediates are known.

The compounds of this invention have an effect on one or more enzymes which utilize folic acid, and in particular metabolic derivatives of folic acid, as a substrate. The action of the compounds appear to be similar in this regard to that of 6(R)-5,10- dideazatetrahydrofolic acid which is described in U.S. Patent No. 4,684,653. Thus the compounds exhibit particularly strong inhibitory activity against the enzyme glyci- namide ribonucleotide formyltransferase. The compounds also exhibit inhibitory activity against folate enzymes such as dihydrofolate reductase and thymidylate synthetase. For example, the IC_™ value against human T-cell derived lymphoblastic leukemia cells (CCRF-CEM), for N-{3-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydro- pyrido[2,3-d]pyrimidin-6-yl)ethyl]-pyridin-5-ylcarbonyl}-L-glutamic acid is 0.1 μ/mL while the glycinamide ribonucleotide formyltransferase/K/ is 0.126 μM.

The compounds can be used, under the supervision of qualified professionals, to inhibit the growth of neoplasms including choriocarcinoma, leukemia, adenocarci- noma of the female breast, epidermic cancers of the head and neck, squamous or small-cell lung cancer, and various lymphosarcomas. The compounds can also be used to treat mycosis fungoides, arthritis, and psoriasis. The compounds can be administered orally but preferably are administered parenterally, alone or in combina¬ tion with other therapeutic agents including other anti-neoplastic agents, steroids, etc., to a mammal suffering from neoplasm and in need of treatment. Parenteral routes of administration include intramuscular, intrathecal, intravenous and intra-arterial. Dosage regimens must be titrated to the particular neoplasm, the condition of the patient, and the response but generally doses will be from about 10 to about 100 mg/day for 5-10 days or single daily administration of 250-500 mg, repeated periodi¬ cally; e.g. every 14 days. While having a low toxicity as compared to other anti- metabolites now in use, a toxic response often can be eliminated by either or both of reducing the daily dosage or administering the compound on alternative days or at longer intervals such as every three days. Concomitant administration of folic acid as a rescue therapy also may be indicated. Oral dosage forms include tablets and cap¬ sules containing from 1-10 mg of drug per unit dosage. Isotonic saline solutions con- taining 20-100 mg/ml can be used for parenteral administration. The following examples will serve to further illustrate the invention. In the NMR data, "s" denotes singlet, "d" denotes doublet, "t" denotes triplet, "q" denotes quartet, "m" denotes multiplet, and "br" denotes a broad peak.

EXAMPLE 1 Dimethyl N-(2-Chloropyridin-5-yicarbonyl)-L-glutamate

Twelve millimols of 2-chloropyridine-5-carboxylic acid, 50 mmol of thionyl chloride, ten drops of dimethylformamide, and 100 mL of benzene were heated at reflux under nitrogen for 3 hours. Volatile materials were evaporated and 50 mL of chloroform were added to the residue. The mixture was added to a solution of 14 mmols of dimethyl glutamate hydrochloride and 27 mmol of triethylamine in 100 mL of chloroform and the resulting solution was stirred at room temperature for 12 hours. This mixture then was washed with 100 mL of water and 100 mL of brine, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to give dimeth¬ yl N-(2-chloropyridin-5-ylcarbonyl)-L-glutamate which can be further purified by flash column chromatography, using 1 :1 ethyl acetate :hexanes as eluent. mp 100- 102°C; Η NMR (CDC1₃, 300 MHz) δ 2.12-2.22 (m, 1 H), 2.25-2.34 (m, 1 H), 2.49- 2.55 (m, 2 H), 3.69 (s, 3 H), 3.79 (s, 3 H), 4.73-4.80 (m, 1 H), 7.42 (d, 1 II, J = 8.4 Hz), 7.64 (d, 1 H, 7.1 Hz), 8.12 (dd, 1 H, J = 8.4, 2.4 Hz), 8.85 (d, 1 H, J = 2.4 Hz); ¹³C NMR (CDC1₃, 67.9 MHz) δ 26.5, 30.2, 52.0, 52.5i, 52.6, 124.2, 128.2, 137.8, 147.5, 154.5, 164.3, 171.9, 173.9; IR (Nujol) 3300, 1755, 1720, 1630, 1580, 1525, 1210, 1 160, 1 100, 1095, 1015, 975, 850, 770 cm^"1; MS m/e (relative intensity) 314 (0.6%), 257, 255, 142, 140; HRMS Calcd. for C_{] 3}H_{] 5}C1N_?0₅ 314.0670, found 314.0673.

Anal. Calcd. for C^H^CIN^: C, 49.61; H, 4.80; N, 8.90; Cl, 1 1.26. Found: C, 49.79; H, 5.01 ; N, 8.87; Cl, 11.36.

EXAMPLE 2

Dimethyl N-{2-[2-(2-Pivaloylamino-4-hydroxypyrido[2,3-dJpyrimidin-6- yl)ethynyl]pyridin-5-ylcarbonyl}-L-glutamate

A solution of 2-pivaloylamino-4-hydroxy-6-ethynylpyrido[2,3-d]pyrimidine (7.5 mmol.), dimethyl N-(2-chloropyridin-5-ylcarbonyl)-L-glutamate (10 mmol), PdCl₉

(20 mg), PPh3 (60 mg), Cul (45 mg), triethylamino (2 mL) and acetonitrile (100 mL) was heated under reflux under nitrogen for two hours. After evaporation of the solvent under reduced pressure, the residual material was taken up in chloroform (100 mL) and washed with water (2 x 100 mL). The chloroform layer was dried over anhy¬ drous magnesium sulfate and evaporated under reduced pressure to give dimethyl N- {2-[2-(2-pivaloylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-yl)ethynyl]pyridin-5-yl- carbonyl}-L-glutamate as an oil which was further purified by flash column chroma- tography, using 1 :39 methanol :methylene chloride as eluent; mp 220-222°C; Η NMR (CDC1₃, 270 MHz) δ 1.36 (s, 9 H), 2.1 1-2.34 (m, 2 H), 2.61 (t, 2 H, J= 7 Hz), 3.68 (s, 3 II), 3.80 (s. 3 H), 4.88-4.95 (m, 1 H), 7.51 (d, 1 H, J = 8.1 Hz), 8.14 (dd, 1 H, J = 8.1 , 1.6 Hz), 8.27 (d, 1 II, J = 7.7 Hz), 8.54 (d, 1 II, J = 1.6 Hz), 8.80 (d, 1 H, J - 1.7 Hz), 9.04 (br s, 1 ). 9.07 (br s, 1 H), 12.20 (br s, 1 H); ¹³C NMR (CDCI₃, 67.9 MHz) δ 26.5, 26.6, 30.3, 40.4, 51.8, 52.4, 52.5, 86.8, gl.7, 1 14.8, 1 15.8, 126.7, 128.5, 135.5, 139.0, 144.8, 148.9. 150.1 , 158.1 , 158.3, 160.2, 165.0, 172.5, 173.6, 181.0; IR (Nujol) 3180, 2210, 1740, 1670, 1620, 1595, 1545, 1475, 1340, 1265, 1 145, 1015, 970, 925, 865, 815, 775 cm^{' 1} : MS m/e (relative intensity) 548 (19%), 491 (66%), 374 (55%), 316 (20%); HRMS Calcd. for C_7?H₂₉N₆0₇ 548.2019, found 548.2015. Anal. Calcd. for C₂₇II₉₉N₆O₇: C, 59.12 H. 5.15; N, 15.32. Found: C, 59.39; H,

5.24 N, 15.22.

EXAMPLE 3

Dimethyl N-{2-[2-(2-Pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3- djpyrimidin-6-yl)ethyl]pyridin-5-ylcarbonyl}-L-glutamate

A suspension of dimethyl N-{2-[2-(2-pivaloylamino-4-hydroxypyrido[2,3-d]- pyrimidin-6-yl)ethynyl]pyridin-5-ylcarbonyl}-L-glutamate (1.6 mmol) and 10% palladium on carbon (1.50 g) in trifluoroacetic acid (20 mL) was shaken on a Parr shaker at 50 psi of hydrogen for 84 hours. The suspension was diluted with chloro¬ form (200 mL) and filtered through Celite. After evaporation of the solvents under reduced pressure, the residue was purified by flash column chromatography, using 1 :9 methanokmethylene chloride as the eluent to yield dimethyl N-{2-[2-(2-pivalo- ylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)ethyl]pyridin-5- ylcarbonyl}-L-glutamate in 73% yield, mp (dec.) 190-193°C; Η NMR (CD₃OD/CDCl₃, 270 MHz) δ 1.35 (S, 9 H), 1.81-1.90 (m, 3 H), 2.15-2.25 (m, 1 H), 2.30-2.38 (m, 1 H), 2.59 (t, 2 H, J = 7.3 Hz), 2.75-2.88 (m, 1 H), 3.03-3.13 (m, 3 H), 3.42-3.50 (m, 1 H), 3.75 (S, 3 H), 3.84 (S, 3 H), 4.74-4.80 (m, 1 H), 7.45 (d, 1 II, J = 8.0 Hz), 7.64 (S, 1 H), 8.23 (dd, 1 II, J = 8.0, 2.1 Hz), 9.00 (d, 1 H, J = 2 Hz); IR (KBr) 3385, 3240, 3180, 3055, 2915. 2845, 1745, 1640. 1600, 1570. 1540, 1455. 1200, 1020, 765 cm^{" 1}; MS m/s (relative intensity) 556 (9%), 397 (10%). 353 (16%), 263 (40%), 249 (100%); HRMS Calcd. for G,₇H₃₆N₆0₇ 556.2645, Found 556.2631 Anal. Calcd. for C^H^N^: C, 58.26; H, 6.52; N, 15.10. Found: C, 58.43; H, 6.32; N, 15.31.

EXAMPLE 4

N-{2-[2-(2-Amino-4-hydroxy-5,6,7,8-tetrahydropyridof2,3-d]pyrimidin-6- yl)ethyI]pyridin-5-ylcarbonyI}-L-glutamic Acid

A solution of dimethyl N-{2-[2-(2-pivaloylamino-4-hydroxy-5,6,7,8-tetrahydro- pyrido[2,3-d]pyrimidin-6-yl)ethyl]pyridin-5-ylcarbonyl}-L-glutamate (0.75 mmol) in 1 M sodium hydroxide solution (50 mL) was stirred at room temperature for 96 h. The pH was adjusted to 4 by the addition of 1 M hydrochloric acid and the solid collected by filtration, washed with ether, and dried in vacuo to yield N-{2-[2-(2- amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)ethyljpyridin-5-y]- carbonyl} -L-glutamic acid, 51% yield, mp (dec.) 230-233°C; Η NMR (DMSO-^, 270 MHz) δ 1.69-1.85 (m, 2 H), 1.95-2.10 (m, 2 H), 2.38-2.46 (m, 4 H), 2.83-294 (m, 3 H), 3.26-3.30 (m, 2 H), 4.40-4.45 (m, 1 H), 6.16 (br s, 2 H), 6.34 (br s, 1 H), 7.42- 7A6 (m, 1 H), 8.18-8.22 (m, 1 H), 8.64 (d,l II, J = 7.3 Hz), 8.99 (d, 1 1 1 , .1 = 2 Hz), 10.08 (br s, 1 H); IR (KBr) 3500-2500, 2915, 2850, 1630, 1540. 1475, 1385, 1350, 1295, 765, 640 cm^{' 1}, HRMS Calcd. for 2_Q ^U25^6°6 ⁴⁴⁵-¹⁸³⁶- ^found 445.1849.

EXAMPLE 5 Dimethyl N-(3-Bromopyridin-5-ylcarbonyl)-L-glutamate

In a similar fashion to that described in Example 1 , there is obtained from 3- bromopyridine-5-carboxylic acid (alternatively known as 5-bromonicotinic acid) in an 84% yield dimethyl N-(3-bromopyridin-5-ylcarbonyl)-L-glutamate as an oil; Η NMR (CDC1₃, 300 MHz) δ 2.14-2.24 (m, 1 H), 2.26-2.33 (m, 1 II), 2.49-2.56 (m. 2 H), 3.70 (s, 3 H), 3.80 (s, 3 H), 4.76-4.80 (m, 1 H), 7.45 (d, 1 H, J= 6.9 Hz), 8.30 (t, 1 H, J= 2 Hz), 8.81 (d, 1 H, J = 2 Hz), 8.95 (d, 1 H, J = 2 Hz); ^πC NMR (CDC1₃, 67.9 MHz) δ 26.6, 30.2, 51.9, 52.5, 52.6, 120.7, 130.6, 137.7, 146.2, 153.4. 164.0, 171.8, 173.7; IR (Neat) 3330, 3060, 2950, 2850, 1740, 1670, 1650, 1580, 1535, 1435, 1240, 1215. 1 170, 1095, 1045, 1020, 895, 695 cm-1; MS 360, 358 (19%), 301 , 299 (62%), 186. 184 (100%, M+); HRMS Calcd. for C₁₃H_{] 5}BrN₂0₅ 358.0164, found 358.0170. Anal. Calcd. for C^H^BrN^; C, 43.47; H, 4.21 ; N, 7.80; Br, 22.25. Found:

C, 43.47; H. 4.40; N, 8.05; Br, 22.25. EXAMPLE 6

Dimethyl N-{3-[2-(2-PivaIoylamino-4-hydroxypyrido[2,3-d]pyrimidin-6- yl)ethynyl]pyridin-5-ylcarbonyl}-L-glutamate

By subjecting dimethyl N-(3-bromopyridin-5-ylcarbonyl)-L-glutamate to the pro- cedure of Example 2 but utilizing Pd(PPh₃)₄ (2%) as the catalyst and dimethyl- formamide as the solvent, there is obtained dimethyl N-{3-[2-(2-pivaloylamino-4- hydroxypyrido[2,3-d]pyrimidin-6-yl)ethynyl]pyridin-5-ylcarbonyl}-L-glutamate in a 46% yield; mp 220-222°C; Η NMR (CDC1₃, 270 MHz) δ 1.34 (s, 9 H), 2.10-2.40 (PI, 2 H), 2.64-2.70 (m, 2 H), 3.69 (s, 3 H), 3.83 (s, 3 H), 4.88-4.94 (m, 1 H), 8.28 (s, 1 II), 8.35 (br d, 1 H), 8.51 (d, 1 H, J= 2 Hz), 8.78 (d, 1 H, J= 1.7 Hz), 8.94 (d, 1 H, J = 1 .7 FIz), 9.02 (d, 1 H, J = 2 Hz), 9.15 (brs, 1 H), 12.26 (br s, 1 H); ¹³C NMR (CDC1₃, 67.9 MHz) δ 26.6, 30.3, 40.6, 51.9, 52.5, 52.8, 88.7, 89.0, 1 14.9, 116.2, 1 19.0, 129.2, 137.6, 138.8, 148.1, 150.2, 154.2, 157.9, 158.1 , 160.1, 165.4, 173.1 , 173.4, 181.2; IR (nujol) 3275, 1735, 1705, 1665, 1615, 1600, 1580, 1545, 1325, 1270, 1210, 1 145, 805 cm^"1; MS m/e (relative intensity) 548 (52%), 491 (100%), 374 (52%), 316 (65%); HRMS Calcd. for C₂₇H_2gN₆O₇ 548.2019, found 549.2024.

EXAMPLE 7

Dimethyl N-{3-[2-(2-Pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3- d]pyrimidin-6-yl)ethyl]pyridin-5-ylcarbonyl}-L-glutamate

By subjecting dimethyl N-{3-[2-(2-pivaloylamino-4-hydroxypyrido[2,3-d]- pyrimidin-6-yl)ethynyl]pyridin-5-ylcarbonyl}-L-glutamate to the procedure of Example 3, there is obtained dimethyl N-{3-[2(2-pivaloylamino-4-hydroxy-5,6,7,8- tetrahydropyrido[2,3-d]pyrimidin-6-yl)ethyl]pyridin-5-ylcarbonyl}-L-glutamate in 41% yield; mp 191-195°C; 1H NMR (DMSO d_& 300 MHz) δ 1.16 (s, 9 H), 1.50-1 ,65 (m. 3 H), 1.90-2.02 (m, 1 H), 2.05-2.16 (m, 1 H), 2.44 (t, 2 H, J = 7.3 Hz), 2.54-2.6) (m, 1 H), 2.64-2.78 (m, 2 H), 2.83-2.90 (m, 1 H), 3.23-3.30 (m, 1 H), 3.54 (s, 3 H), 3.62 (s, 3 FI), 4.42-4.49 (m, 1 H), 6.56 (br s, 1 H), 8.09 (br s, 1 H), 8.60 (d, 1 H, J = 1.1 Hz), 8.84 (d, 1 H, J = 1.3 Hz), 8.96 (d, 1 H, J = 7.4 Hz), 10.60 (br s, 1 H), 1 1.25 (br S, 1 H); IR (KBr) 3450-3200, 2960, 2930, 1730, 1675, 1650, 1570. 1480, 1460, 1205, 1 140, 800, 720 cm^{" 1} ; MS m/e (relative intensity) 556 (12%). 525 (1 1 %), 397 (94%), 382 (23%). 354 (72%), 298 (27%), 250 (100%); HRMS Calcd. for C^II^NgO.- 556.2645, found 556.2634. EXAMPLE 8

N-{3-[2-(2-Amino-4-hydroxy-5,6,7,8-tetrahydropyridof2,3-d]pyrimidin-6- yl)ethyl]pyridin-5-ylcarbonyl}-L-glutamic Acid

By subjecting dimethyl N-{3-[2(2-pivaloylamino-4-hydroxy-5,6,7,8-tetrahydro- pyrido[2,3-d]pyrimidin-6-yl)ethyl]pyridin-5-ylcarbonyl}-L-glutamate to the proce¬ dure of Example 4, there is obtained N-{3-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydro- pyrido[2,3-d]pyrimidin-6-yl)ethyl]pyridin-5-ylcarbonyl} -L-glutamic acid in 33%> yield, mp 210-214°C; Η NMR (DMSO-^, 300 MHz) δ 1.52-1.58 (m, 4 FI), 1.75- 1.85 (m, 2 H), 1.88-1.96 (m, 1 H), 2.00-2.10 (m, 1 H), 2.34 (t, 2 H, J = 7.4 Hz), 3.16- 3.22 (m, 2 H), 4.37-4.40 (m, 1 H), 6.1 1 (br s, 2 H), 6.28 (br s, 1 H), 8.07 (s, 1 H), 8.62 (d, 1 H, J = 1.8 Hz), 8.828.86 (m, 2 H), 9.90 (br s, 1 H), 12.50 (br s, 2 H); IR (KBr) 3500-3150, 2915, 2850, 1710, 1650, 1545, 1390, 1350, 1310 cm^"1; FABMS Calcd. for C₂₀H₂₅N₆O₆ 445.1836, found 445.1852.

EXAMPLE 9 Dimethyl N-(5-Bromopyridin-2-ylcarbonyl)-L-glutamatc

In a similar fashion to that described in Example 1 , there is obtained from 5- bromopyridine-2-carboxylic acid (alternatively known as 5-bromopicolinic acid) in 59% yield dimethyl N-(5-bromopyridin-2-ylcarbonyl)-L-glutamate as an oil; H NMR (CDC1₃, 300 MHz) δ 2.09-2,19 (m, 1 H), 2.30-2.38 (m, 1H), 2.41-2.48 (m. 2H), 3.63 (s, 3H)^', 3.77 (s. 3 H), 4.77-4.84 (m, 1 H), 7.96 (dd, 1 H. J = 8.4, 2.0 Hz), 8.04 (d, 1 II, J = 8 4 Hz), 8.38 (d, 1 H, J = 8.2), 8.62 (d, 1 H, J = 2.0 Hz); ¹³C NMR (CDC1₃, 75.6 MHz) δ 27.5, 30.0, 51.6, 51.8, 52.6, 123.7, 124.3, 139.9, 147.5, 149.4, 163.5, 171.8, 172.9; IR (Neat) 3380, 2955, 1740, 1680, IS75, 1520, 14S5, 1440, 1260. 1210, 1 170, 1085, 1010, 855 cm-1; MS m/e (relative intensity) 360 (3%), 358 (3%), 329 (10%), 328 (9%), 327 (1 1%), 326 (8%), 301 (97%), 299 (100%), 269 (38%)7 267 (38%), 241 (27%), 239 (28%), 186 (84%), 185 (845), 158 (66%), 156 (66%); HRMS Calcd. for C_{] 3}H₁₅BrN₂O₅ 358.0164, found 358.0154. Anal. Calcd. for C_{] 3}H_{] 5}BrN₉0₅: C, 43.47; H, 4.21 ; N, 7.00; Br, 22.25. Found: C, 43.19; I I, 4.22; N, 7.75; Br, 22. ^"

The starting material can be obtained as follows: 5-Bromo-2-ethynylpyridine (3.20 g, 17.58 mmol) was added to a solution of potassium permanganate (5.60 g, 35.40 mmol) in water (500 mL). The solution was heated under reflux for 5 hours. Part of the 5-bromo-2-ethynylpyridine (450 mg, 2.47 mmol, 14%) was recovered from the condenser where it had sublimed. The solution was filtered through Celite to remove manganese dioxide, and the solvent was evaporated from the filtrate. Dilute hydrochloric acid (50 mL, 0.5 M) was added to the residue and the solid was filtered off and dried in the vacuum oven to give 2.18 g (10.79 mmol, 71% yield based on recovered starting material) of the product. This was recrystallized from water to give white crystals, mp 173-174°C; Η NMR (DMSO^, 300 MHz) δ 7.91 (d, 1 H, J = 8.5), 8.17 (d, 1 H, J = 8.5 Hz), 8.77 (s, 1 H); IR (KBr) 3500-3300, 1700, 1320, 1235, 1085, 1015, 1005, 790, 690; MS m/e (relative intensity) 203 (12%), 201 (13%), 159 (99%), 157 (100%), 78 (86%); HRMS Calcd. for C₆H₄BrNO₂ 200.9425, found 200.9426.

EXAMPLE 10 Dimethyl N-{5-[2-(2-Pivaloylamino-4-hydroxypyrido|2,3-d] pyrimidin-6- yl)ethynyl]pyridin-2-ylcarbonyl}-L-glutamate

Following the procedure of Example 2, there is obtained from dimethyl N-(5- bromopyridin-2-y lcarbonyl)-L-glutamate, dimethyl N- { 5-[2-(2-pivaloylamino-4- hydroxypyrido[2.3-d]pyrimidin-6-yl)ethynyl]pyridin-2-ylcarbonyl}-L-glutamate; mp 223-225°C; Η NMR (CDCL_j, 300 MHz) δ 1.35 (s, 9 H), 2.14-2.22 (m, 1 II), 2.35- 2.44 (m, 1 H), 2.46-2.53 (m, 2 H), 3.67 (s, 3 H), 3.80 (s, 3 H), 4.83-4.90 (m, 1 H). 7.99 (dd, 1 H, J = 8.1, 1.9 Hz), 8.19 (d, 1 H, J = 8.1 Hz), 8.50 (d, 1 H, J = 8.6 Hz), 8.66 (d, 1 H, J= 1.6 Hz), 8.73 (d, 1 H, J= 1.6 Hz), 9.00 (d, 1 H, J= 1.9 Hz), 12.18 (br s, 1 FI); ¹³C NMR (CDC1_3> 67.9 MHz) δ 26.5, 27.2, 30.0, 40.3, 51.5, 51.6, 52.4, 89.1 , 90.4. 1 14.6, 1 15.9, 121.7, 122.0, 128.2, 138.5, 139.6, 147.9, 149.8, 150.3, 157.9, 160.3, 163.4, 171.8, 172.9, 180.8; IR (KBr) 3380, 3180, 2955, 1740, 1670, 1620,

1600, 1545, 1510. 1475, 1435, 1370, 1265, 1220, 1 135 cm^"1; MS m/e (relative inten¬ sity) 548 (34%), 491 (98%), 374 (35%), 347 (100%), 288 (42%), 262 (44%). 174 (36%), 91 (39%): HRMS Calcd. for C₂₇H₂₈N₆O_? 548.2019, found 548.2029. Anal. Calcd. for C₂₇H_2gN₆O₇: C, 59.12; H, 5.15; N, 15.32. Found C,58.85; H,

4.91 ; N, 15.07.

EXAMPLE 11

Dimethyl N-{5-[2-(2-PivaloyIamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3- d]pyrimidin-6-yl)ethyllpyridin-2-ylcarbonyl}-L-glutamate

Upon subjecting dimethyl N-{5-[2-(2-pivaloylamino-4-hydroxypyrido[2.3-d]- pyrimidin-6-yl)ethynyl]pyridin-2-ylcarbonyl}-L-glutarnate to the procedure of Example 3, there is obtained dimethyl N-{5-[2-(2-pivaloylamino-4-hydroxy-5.6,7,8- tetrahydropyrido[2,3-dJpyrimidin-6-yl)ethyl]pyridin-2-ylcarbonyl}-L-glutamate in 71% yield, mp 178-180°C; Η NMR (CDC1₃, 300 MHz) δ 1.30 (s, 9 H), 1.63-1.74 (m, 2 H), 1.77-1.85 (m, 1 FI), 2.10-2.20 (m, 2 H), 2.32-2.40 (m, 1 H), 2.42-2.51 (m, 2 H), 2.71-2.88 (m, 3 H), 2.98-3.06 (m, 1 H), 3.35-3.40 (m, 1 H), 3.65 (s, 3 H), 3.78 (s, 3 H), 4.83-4.90 (m, 1 H), 5.40 (br s, 1 H), 7.66 (dd, 1 H, J= 8.0, 1.4 Hz), 8.07 (d, 1 H, J = 8.0 Hz), 8.41 (d, 1 H, J= 1.5 Hz), 8.50 (d, 1 H, J = 8.6 Hz), 9.10 (br s, 1 H); ¹³C NMR (CDC1₃, 67.9 MHz) δ 25.0, 26.7, 27.6, 30.0, 30.2, 30.3, 34.3, 40.2, 45.9, 51.5, 51.7, 52.5, 89,2, 122.1, 136.9, 140.7, 147.2, 148.3, 148.5, 157.8, 160.3, 164.4, 172.0, 172.9, 180.3: IR (KBr) 3415, 3240, 2945, 1740, 1640, 1570, 1510, 1455, 1200, 1 160, 765 cm^"1; MS m/e (relative intensity) 556 (18%), 499 (51%), 439 (38%), 397 (83%), 356 (61%), 353 (60%), 296 (41%), 270 (40%), 250 (100%), 165 (71 %); HRMS Calcd. for C₂₇II₃₆N₆O₇ 556.2645, found 556.2656.

EXAMPLE 12

N-{5-[2-(2-Amino-4-hydroxy-5,6,7,8-tctrahydropyrido[2,3-d]pyrimidin-6- yI)ethyI]pyridin-2-ylcarbonyI}-L-glutamic Acid

Upon subjecting dimethyl N-{5-[2-(2-pivaloylamino-4-hydroxy-5,6,7.8-tetrahy- dropyridof 2,3-dJpyrimidin-6-yl)ethyl]pyridin-2-ylcarbonyl } -L-glutamate to the procedure of Example 4, there is obtained N-{5-[2-(2-amino-4-hydroxy-5,6,7,8-tetra- hydropyrido[2,3-d]pyrimidin-6-yl)ethyl]pyridin-2-ylcarbonyl} -L-glutamic acid in 63% yield, mp (dec.) 222-225°C: Η NMR (DMSO-J^, 270 MHz) δ 1.55-1.60 (m, 4 H),1.78-1.87 (m, 1 H), 1.97-2.12 (m, 2 H), 2.27 (t,2 H, J = 7.1 Hz), 2.73-2.80 (m, 3 H), 3.16-3.20) (m, 1 H), 4.39-4.46 (m, 1 H), 6.20 (br s, 2 H), 6.29 (br s,l H), 7.84 (dd. 1 FI, J = 8.0, 1.4 Hz), 7.93 (d, 1 H, J = 8.0 Hz), 8.52 (s,l H), 8.75 (d, 1 H, J - 7.9 Hz), 9.95 (br s, 1 H); IR (KBr) 3500-3200, 2925, 2855, 1710, 1655, 1570, 1475. 1465, 1385 FABMS Calcd. for C-₂₀H₂₅N₆O₆ 445.1836, found 445.1852.

EXAMPLE 13

Dimethyl N-(2-TrimethyIsilylcthynylpyridin-5-yl- carbonyl)-L-glutamate

A solution of dimethyl N-(2-chloropyridin-5-ylcarbonyl)-L-glutamate (1.92 g, 6.10 mmol), trimethylsilylacetylene (1.00 g, 10.18 mmol), PdCl₂ (25 mg, 0.14 mmol, 2%), Cul (50 mg, 0.26 mmol), PPh₃ (60 mg, 0.23 mmol), triethylamine (2 mL) and acetonitrile (100 mL) was heated at reflux under nitrogen for 12 hours. The solvent was evaporated and the residue taken up in 100 mL of chloroform, washed with water (2 x 100 mL), and dried over magnesium sulfate. The solvent was evaporated and the residue purified by flash column chromatography, using 2:3 ethyl acetate.hexanes as the eluent to yield dimethyl N-(2-trimethylsilylethynylpyridin-5-ylcarbonyl)-L-gluta- mate as a clear oil. (39%); 1H NMR (CDC1₃, 300 MHz) δ 0.17 (s, 9 H), 2.00-2.08 (m, 1 H), 2.13-2.24 (m, 1 H), 2.35-2.44 (m, 2 H), 3.56 (s, 3 H), 3.67 (s, 3 H), 4.64-4.71 (m, 1 H), 7.41 (d, 1 H, J= 8.1 Hz), 7.44 (d, 1 H, J = 7.4 Hz), 8.04 (dd, 1 H, J = 8.1, 2 Hz), 8.94 (d, 1 H, J = 2 Hz); ¹³C NMR (CDC1₃, 67.9 MHz) δ 0.6, 26.4, 30.1, 51.7, 52.3, 52.4, 97.6, 102.8, 126.6, 127.8, 135.2, 145.3, 148.4, 164.7, 171.8, 173.5; IR (Neat) 3320, 2950, 2155, 1730, 1660, 1580, 1530, 1470, 1430, 1360, 1250, 1205, 1 160, 1095, 1005, 865, 835, 765, 750 cm^"'; MS m/e (relative intensity) 376 (20%), 344 (10%), 317 (65%), 202 (100%); HRMS Calcd. for C_{] g}H₂₄N₉O₅Si 376.1455, found 376.1455. Anal. Calcd. for C_{l g}H₂₄N₂O₅Si: C, 57.43; H~ 6.43; N, 7.44. Found: C, 57.24; II, 6.64; N, 7.39.

EXAMPLE 14

Dimethyl N-(2-Ethynylpyridin-5-ylcarbonyl)-L-glutamate

Potassium carbonate (220 mg, 1.59 mmol) was added to a solution of dimethyl N-(2-trimethylsilylethynylpyridin-5-ylcarbonyl)-L-glutamate (870 mg, 2.31 mmol) in methanol (100 mL). After stirring for 2 hours at room temperature under nitrogen, the solvent was evaporated under reduced pressure and the residue was taken up in chlor¬ oform (50 mL). This solution was washed with water (2 x 50 mL), dried over magnesium sulfate and evaporated. The residue was further purified by flash column chromatography using ethyl acetate as the eluent to yield give dimethyl N-(2-ethy- nylpyridin-5-ylcarbonyl)-L-glutamate (71%) as a liquid; Η NMR (CDC1₃, 300 MHz) δ 2.04-2.12 (m, 1 H), 2.17-2.26 (m, 1 H), 2.40-2.49 (m. 2 H), 3.27 (s. 1 H), 3.57 (s, 3 II), 3.68 (s, 3 H), 4.65-4.72 (m, 1 H), 7.45 (d, 1 H, J = 8.1 Hz), 7.77 (d, 1 H, J = 7.4 Hz), 8.07 (dd, 1 H, J = 8.1, 2 Hz), 8.96 (d, 1 H, J = 2 Hz); ¹³C NMR (CDC1₃, 67.9 MHz) δ 26.4, 30.1, 51.7, 52.3, 52.4, 79.5, 82.0, 126.9, 128.4, 135.3, 144.6, 148.5, 164.7, 171.8, 173.S; IR (Neat) 3260, 2990, 2950, 2840. 2105, 1735, 1655, 1590, 1535, 1465, 1435, 1365, 1205, 1170, 1100, 1020, 850, 775 cm-1; MS m/e (relative intensity) 304 (13%), 273 (15%), 245 (78%), 174 (54%), 130 (100%); HRMS Calcd. for C_{1 5}H₁₆N₇O₅: 304.1059, found 304.1037. Anal. Calcd. for C_{] 5}H₁₆N₂O₅: C, 59.19; PI, 5.30~ N, 9.21. Found: C, 59.19; H, 5.55; N, 9.10.

By following the procedures of U.S. Patent No. 4,818,819, dimethyl N-(2-ethyn- ylpyridin-5-ylcarbonyl)-L-glutamate and 2-pivaloylamino-4-hydroxy-6-bromopyrido- [2,3-d]pyrimidine are coupled to yield dimethyl N-{2-[2-(2-pivaloylamino-4-hydroxy- pyrido[2,3-d]pyrimidin-6-yl)ethynyl]pyridin-5-ylcarbonyl}-L-glutamate; mp 220- 222°C, which then can be subjected as previously described to the procedure of Example 2.

EXAMPLE 15

Hard gelatin capsules are prepared using the following ingredients: Quantity

(mg/capsule)

N- { 2- [2-(2-amino-4-hydroxy- 5,6,7,8-tetrahydropyrido [2,3-d]pyrimidin-6-yl)ethyl]- 250 pyridin-5-ylcarbonyl}-

L-glutamic acid

Starch, dried 200

Magnesium stearatc 10

460 mg

EXAMPLE 16

A tablet is prepared using the ingredients below:

Quantity rmg/capsule)

N-{3-[2-(2-amino-4-hydroxy- 5,6,7,8-tetrahydropyrido-

[2,3-d]pyrimidin-6-yl)ethyl]- 250 pyridin-5-ylcarbonyl }- L-glutamic acid

Cellulose, microcrystalline 400 Silicon dioxide, fumed 10

Stearic acid _5_

665 mg

The components arc blended and compressed to form tablets each weighing 665 mg. EXAMPLE 17

nous formulation may be prepared as follows:

Quantity

N- { 5-[2-(2-amino-4-hydroxy-

5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidin-6-yl)ethyl]pyridin-2- ylcarbonyl } -L-glutamic acid 100 mg

Isotonic saline 1 ,000 mL

Claims

What is claimed is:

1. A compound selected from the group consisting of (0 a fused pyrimidine of the formula:

in which R¹ is -OH or -NH₂, R is -OH or a carboxylic acid protecting group, R is -H or an amino protecting group, Z is pyridinediyl in which the valence bonds originate from nonadjacent carbon atoms of the ring; and n has a value of 2 or 3, and the configuration about the carbon atom designated * is L, and (//) a pharmaceutically acceptable salt thereof.

2. A compound according to claim 1 in which Z is pyridine-2,4-diyl.

3. A compound according to claim 1 in which Z is pyridine-2,5-diyl.

4. A compound according to claim 1 in which Z is pyridine-2,6-diyl.

5. A compound according to claim 1 in which Z is pyridine-3,5-diyl.

6. A compound according to claim 1 in which in said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine R¹ is -OH, R² is -OH, R³ is -H, and n has a value of 2.

7. A compound according to claim 6 in which said 5,6,7, 8-tetrahydropyrido[2, 3-d]- pyrimidine is N-{2-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-dJpyrirnidin- 6-yl)ethylJ-pyridin-4-ylcarbonyl} -L-glutamic acid.

8. A compound according to claim 6 in which said 5,6,7,8-tetrahydropyrido[2.3-dJ- pyrimidine is N-{2-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyridof2,3-d]pyrimidin- 6-yl)ethyl]-pyridin-5-ylcarbonyl} -L-glutamic acid.

9. A compound according to claim 6 in which said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine is N-{2-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin- 6-yl)ethyl]-pyridin-6-ylcarbonyl} -L-glutamic acid.

10. A compound according to claim 6 in which said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine is N-{4-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin- 6-yl)ethyl]-pyridin-2-ylcarbonyl}-L-glutamic acid.

1 1. A compound according to claim 6 in which said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine is N-{5-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin- 6-yl)ethyl]-pyridin-2-ylcarbonyI} -L-glutamic acid.

12. A compound according to claim 6 in which said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine is N-{3-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin- 6-yl)ethyl]-pyridin-5-ylcarbonyl} -L-glutamic acid.

13. A compound according to claim 1 in which in said 5,6,7,8-tetrahydropyrido[2,3- djpyrimidine R is -NH₂, R is -OFI, R^" is -II, and n has a value of 2.

14. A compound according to claim 13 in which said 5,6,7, 8-tetrahydropyrido[2, 3-d]- pyrimidine is N-{2-[2-(2,4-diamino-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)- ethyl]-pyridin-4-ylcarbonyl} -L-glutamic acid.

15. A compound according to claim 13 in which said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine is N-{2-[2-(2,4-diamino-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6- yl)ethyl]-pyridin-5-ylcarbonyl} -L-glutamic acid.

16. A compound according to claim 13 in which said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine is N-{2-[2-(2,4-diamino-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6- yl)ethyl]-pyridin-6-ylcarbonyl}-L-glutamic acid.

17. A compound according to claim 13 in which said 5,6,7,8-tetrahydropyrido[2,3-d|- pyrimidine is N-{4-[2-(2,4-diamino-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6- yl)ethyl]-pyridin-2-ylcarbonyl} -L-glutamic acid.

18. A compound according to claim 13 in which said 5,6,7,8-tetrahydropyrido[2,3-d]- pyrimidine is N-{5-[2-(2,4-diamino-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6- yl)ethyl]-pyridin-2-ylcarbonyl} -L-glutamic acid.

19. A compound according to claim 13 in which said 5,6,7,8-tetrahydropyrido[2,3-dj- pyrimidine is N-{3-f2-(2,4-diamino-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6- yl)ethyl]-pyridin-5-ylcarbonyl} -L-glutamic acid.

20. The method of inhibiting neoplastic growth in a mammal which growth is dependent on folic acid or a metabolic derivative of folic acid as a substrate, which comprises administering to the mammal in a single or multiple dose regimen an effective amount of a compound according to claim 1.

21. A pharmaceutical composition for inhibiting neoplastic growth in a mammal which growth is dependent on folic acid or a metabolic derivative of folic acid as a substrate, which comprises an amount of a compound according to claim 1 which upon administration to the mammal in a single or multiple dose regimen is effective to inhibit said growth, in combination with a pharmaceutically acceptable carrier.