N-(5,6,7,8-tetrahydropyrido(2,3-D)pyrimidin-6-yl-alkanoyl)-glutamic acid derivatives.

The present invention pertains to the individual diastereomers and to the diastereomeric mixture of glu­tamic acid derivatives of the formula: <chemistry id="chem0001" num="0001"><img file="EP0343801A2_D0001.tif" /></chemistry> in which: R¹ is -OH or -NH₂; R² is hydrogen or a carboxy protecting group; R³ is a carbon-carbon bond, alkylene of 1 to 4 car­bon atoms, cyclohexylene, or <chemistry id="chem0002" num="0002"><img file="EP0343801A2_D0002.tif" /></chemistry> R⁴ is hydrogen or an amino protecting group; Q is -S- or -O-; R⁵ is hydrogen, chloro or fluoro; and the configuration about the carbon atom designated * is S.

The compounds of Formula IA and IB have an in­hibitory effect on one or more enzymes which utilize folic acid, and in particular metabolic derivatives of folic acid, as a substrate. The compounds thus can be used, alone or in combination, to inhibit the growth of those neoplasms which otherwise depend upon the enzymes so inhibited.

The invention also pertains to the pharmaceuti­cally acceptable salts of the compounds of Formula IA and IB, to processes for the preparation of these com­pounds and their salts, to a method of combatting neo­plastic growth in a mammal, and to pharmaceutical com­positions containing these compounds or their salts.

The term alkylene as used herein denotes a straight or branched divalent aliphatic group of from 1 to 4 carbon atoms including methylene, ethylene, tri­methylene, tetramethylene, 1,1-propylidene, 2,2-propyl­idene, 1,2-propanediyl, 2,3-butanediyl, etc. Analo­gously, cyclohexylene denotes a divalent cycloalkane group of 6 carbon atoms including 1,2-cyclohexylene, 1,3-cyclohexylene, and 1,4-cyclohexylene.

The protecting groups designated by R² and R⁴ and utilized herein denote groups which generally are not found in the final therapeutic compounds but which are intentionally introduced during a portion of the syn­thesis to protect a group which otherwise might react in the course of chemical manipulations, thereafter being removed at a later stage of the synthesis. Since compounds bearing such protecting groups thus are of importance primarily as chemical intermediates (although some derivatives also exhibit biological activity), their precise structure 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, Schröder and Lubke, Academic Press, London and New York, 1965; "Methoden der organischen Chemie", Houben-Weyl, 4th Edition, Vol.15/I, Georg Thieme Verlag, Stuttgart 1974.

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 such as methyl or ethyl and particularly one which is branched at the 1-position such as t.-butyl; and such lower alkyl ester substituted in the 1- or 2-position with (i) lower alkoxy, such as for example, methoxymethyl, 1-meth­oxyethyl, and ethoxymethyl, (ii) lower alkylthio, such as for example methylthiomethyl and 1-ethylthioethyl; (iii) halogen, such as 2,2,2-trichloroethyl, 2-bromo­ethyl, and 2-iodoethoxycarbonyl; (iv) 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 phenacyl. A carb­oxy group can also be protected in the form of an organic silyl group such as tri-lower alkylsilyl, as for example trimethylsilyloxycarbonyl.

Amino groups similarly 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 at the 1-posi­tion, particularly tertiary alkanoyl such as pivaloyl, or a lower alkanoyl group which is substituted in the 1-position, as for example trifluoroacetyl.

A first group of preferred compounds are those wherein R¹ is -OH and each of R² and R⁴ is hydrogen. A first preferred subgroup within this group are those compounds in which R³ is a carbon-carbon bond, methyl­ene, ethylene, trimethylene, tetramethylene, or 1,4-­cyclohexylene. Preferred species within this subgroup include the (R,S) and (S,S) diastereomers of N-[3-(2-­amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]-­pyrimidin-6-yl)propioyl]-L-glutamic acid; N-[4-(2-­amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]-­pyrimidin-6-yl)butyryl]-L-glutamic acid; N-[5-(2-amino-­4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl)pentanoyl]-L-glutamic acid; N-[6-(2-amino-4-hydroxy-­5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl)hexanoyl]-L-glutamic acid; N-[7-(2-amino-4-hydroxy-­5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl)heptanoyl]-L-glutamic acid; and N-[4-(2-{2-amino-4-­hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl}ethyl)cyclohex-1-ylcarbonyl]-L-glutamic acid.

A second preferred subclass are those compounds in which R³ is: <chemistry id="chem0003" num="0003"><img file="EP0343801A2_D0003.tif" /></chemistry> where R⁵ is hydrogen and Q is -S-. Preferred species within this subgroup include the (R,S) and (S,S) diastereomers of N-[5-(2-{2-amino-4-hydroxy-­5,6,7,8-tetrahydropyrido[2,3-d]-pyrimidin-6-yl)ethyl)­thien-2-ylcarbony]-L-glutamic acid; N-[5-(4-{2-amino-4-­hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}­ethyl)thien-2-ylcarbony]-L-glutamic acid; N-[5-(2-{2-­amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrim­idin-6-yl}ethyl)thien-3-ylcarbony]-L-glutamic acid; N-­[4-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-­d]pyrimidin-6-yl}ethyl)thien-3-ylcarbony]-L-glutamic acid; N-[3-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydro­pyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-ylcarbony]-L-­glutamic acid; N-[2-(2-{2-amino-4-hydroxy-5,6,7,8-­tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-3-­ylcarbony]-L-glutamic acid; and N-[5-(2-{2-amino-4-­hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl}ethyl)fur-2-ylcarbony]-L-glutamic acid.

The compounds of the present invention often can be employed advantageously in the form of a pharmaceu­tically acceptable salt. Such forms, including hy­drates thereof, are often crystalline and advantageous for forming solutions or formulating pharmaceutical compositions. 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, aluminium, zinc, ammonium, trimethylammonium, triethan­ olammonium, pyridinium, and substituted pyridinium salts. The mono and disodium salts, particularly the disodium salt, are advantageous.

The compounds of this invention in whcih R³ is alkylene or <chemistry id="chem0004" num="0004"><img file="EP0343801A2_D0004.tif" /></chemistry> can be prepared through catalytic hydrogenation of a compound of the formula: <chemistry id="chem0005" num="0005"><img file="EP0343801A2_D0005.tif" /></chemistry> in which: Z¹ and Z² taken individually are each hydrogen or taken together are a carbon-carbon bond; R¹ is as herein defined; R^2′ is a carboxy protecting group; R^3′ is a carbon-carbon bond alkylene of 1 to 4 car­bon atoms, or <chemistry id="chem0006" num="0006"><img file="EP0343801A2_D0006.tif" /></chemistry> and R^4′ is an amino protecting group.

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.

There is obtained a mixture of diastereomers of Formulas IA and IB in which R^2′ is a carboxy protecting group, and R^4′ is an amino protecting group. These protecting groups can then be removed through acidic or basic hydrolysis, as for example with sodium hydroxide, to yield the compounds of Formula I in which each of R² and R⁴ is hydrogen.

Compounds of Formula II can be prepared utilizing procedures analogous to those described in European Patent Application 87308921.3. Thus in a first embodi­ment, a compound of the formula: <chemistry id="chem0007" num="0007"><img file="EP0343801A2_D0007.tif" /></chemistry> in which X is bromo or iodo and R^4′ is as herein defined, is allowed to react with an unsaturated com­pound of the formula: <chemistry id="chem0008" num="0008"><img file="EP0343801A2_D0008.tif" /></chemistry> in which Z¹, Z², R^2′, and R^3′ are as herein de­fined, in the presence of a palladium/trisubstituted phosphine catalyst of the type described by Sakamoto, <u style="single">Synthesis</u>, <u style="single">1983</u>, 312 <u style="single">et seq</u>.

The compounds of this invention in which R³ is cyclohexylene can be prepared through initial catalytic hydrogenation of a compound of the formula: <chemistry id="chem0009" num="0009"><img file="EP0343801A2_D0009.tif" /></chemistry> in which R^4′ is an amino protecting group and R¹ is a herein defined. Compounds of Formula V in which R¹ is -OH are prepared analogously to the methods described in European Patent Application 87308921.3 and the corresponding compounds in whcih R¹ is -NH₂ are generated therefrom in the manner described above.

Suitable catalysts for the hydrogenation of com­pounds of Formula V include noble metals and noble metal oxides such as palladium or platinum oxide. Thus obtained is a compound of the formula: <chemistry id="chem0010" num="0010"><img file="EP0343801A2_D0010.tif" /></chemistry>

Compounds of Formula VI then are coupled with a protected glutamic acid derivative of the formula: <chemistry id="chem0011" num="0011"><img file="EP0343801A2_D0011.tif" /></chemistry> in which R^2′ is a carboxy protecting group, in the manner generally described in PCT application WO 86/05181, utilizing conventional condensation tech­niques for forming peptide bonds, such as activation of the carboxy group through formation of a mixed an­hydride, treatment with DCC, or use of diphenyl­chlorophosphonate. Protecting groups designated by R^2′ and R^4′ then are removed in the manner described above.

In a third embodiment, compounds of Formula II can be prepared utilizing procedures analogous to those described in European Patent Application 87308921.3. Thus an unsaturated compound of the formula: <chemistry id="chem0012" num="0012"><img file="EP0343801A2_D0012.tif" /></chemistry> in which Z¹, Z², and R^4′ are as herein defined, is allowed to react with compound of the formula: <chemistry id="chem0013" num="0013"><img file="EP0343801A2_D0013.tif" /></chemistry> in which X is bromo or iodo and R^2′, R⁵, and Q are as herein defined, in the presence of a palla­dium/trisubstituted phosphine catalyst of the type de­scribed by Sakamoto, <u style="single">Synthesis</u>, <u style="single">1983</u>, 312 <u style="single">et seq</u>.

There is obtained according to the foregoing processes a compound of Formula II in which R¹ is -OH. When a compound in which R¹ is -NH₂ is desired, this product can be treated with 1,2,4-triazole and (4-­chlorophenyl)dichlorophosphate and the product of this reaction then treated with concentrated ammonia.

Compounds of Formula IX are prepared by coupling a compound of the formula: <chemistry id="chem0014" num="0014"><img file="EP0343801A2_D0014.tif" /></chemistry> in which X, R⁵, and Q are as herein defined, with a protected glutamic acid derivative of formula VII in the manner described above utilizing conventional con­densation techniques for forming peptide bonds

The mixture of the individual diastereomers depicted by Formulas IA and IB can be used therapeuti­cally as such or can be separated mechanically as by chromatography. Alternatively, the individual dia­stereomers can be separated by forming diastereomeric salts with a chiral acid such as the individual enan­tiomers of 10-camphorsulfonic acid, camphoric acid, alpha-bromocamphoric acid, methoxyacetic acid, tartaric acid, diacetyltartaric acid, malic acid, pyrrolidone-5-­carboxylic acid, and the like, and then freeing one or both of the individual diastereomeric bases, optionally repeating the process, so as obtain either or both sub­stantially free of the other; <u style="single">i</u>.<u style="single">e</u>., in a form having an optical purity of &gt;95%. This separation can be ef­fected before or after removal of any protecting groups.

As noted, 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 compounds can be used, under the supervision of qualified professionals, to inhibit the growth of neoplasms including choriocarcinoma, leu­kemia, adenocarcinoma of the female breast, epidermid 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 and psori­asis.

The compounds can be administered orally but preferably are administered parenterally, alone or in combination 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 periodically; e.g. every 14 days. While having a low toxicity as compared to other anti­metabolites 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. Oral dosage forms include tablets and capsules contain­ing from 1-10 mg of drug per unit dosage. Isotonic saline solutions containing 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-[6-(2-Pivaloylamino-4-hydroxypyrido[2,3-d]­pyrimidin-6-yl)hex-5-ynoyl]-L-glutamate

A mixture of 1.94g. (6 mmol.) of 2-pivaloylamino-­4-hydroxy-6-bromopyrido[2,3-d]pyrimidine, 1.6g. (6 mmol.) of dimethyl N-(hex-5-ynoyl)-L-glutamate, 0.11g. of palladium chloride, 0.32g. of triphenylphosphine, 0.05g. of cuprous iodide, and 2.6mL. of triethylamine in 150mL. of acetonitrile was heated at reflux for 3 hours and then cooled to ambient temperature. The sol­vent was removed under reduced pressure and the residue chromatographed on silica gel with 1:9 methanol:­methylene chloride to yield dimethyl N-[6-(2-pivaloyl­amino-4-hydroxypyrido[2,3-d]pyrimidin-6-yl))hex-5-yn­oyl]-L-glutamate, m.p. 159-160^oC. Anal. Calc. for C₂₅H₃₁N₅O₇: C, 58.47; H, 6.08; N, 13.64. Found: C, 58.23; H, 5.97; N, 13.43.

In as similar fashion by substituting an equiva­lent amount of dimethyl N-(pent-4-ynoyl)-L-glutamate for dimethyl N-(hex-5-ynoyl)-L-glutamate in the forego­ing procedure, there can be obtained dimethyl N-[5-(2-­pivaloylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-­yl)pent-4-ynoyl]-L-glutamate. In a representative ex­periment, the following physical constants were obtain­ed for this compound: m.p. 162-163^o C. Anal. Calc. for C₂₄H₂₉N₅O₇: C, 57.71; H, 5.84; N, 14.02. Found: C, 57.94; H, 5.72; N, 13.99.

Likewise from dimethyl N-acryloyl-L-glutamate and dimethyl N(but-3-ynoyl)-L-glutamate there are respec­tively obtained dimethyl N-[3-(2-pivaloylamino-4-hydr­oxypyrido[2,3-d]pyrimidin-6-yl)acryloyl]-L-glutamate and dimethyl N-[4-(2-pivaloylamino-4-hydroxypyrido[2,3-­d]pyrimidin-6-yl)but-3-ynoyl]-L-glutamate.

By substituting an equivalent amount of dimethyl N-(hept-6-enoyl)-L-glutamate for dimethyl N-(hex-5-yn­oyl)-L-glutamate in the foregoing procedure, there can be obtained dimethyl N-[7-(2-pivaloylamino-4-hydroxy­pyrido[2,3-d]pyrimidin-6-yl)hept-6-enoyl]-L-glutamate. In a representative experiment, the following physical constants were obtained for this compound: m.p. 79-­82^oC. Anal. Calc. for C₂₆H₃₅N₅O₇: C, 58.01; H, 6.82; N, 13.53. Found: C, 58.47; H, 6.48; N, 12.80.

Dimethyl N-(hex-5-ynoyl)-L-glutamate can be ob­tained by allowing hex-5-ynoic acid chloride (obtained by treating hex-5-ynoic acid with thionyl chloride) to react with dimethyl L-glutamate in the presence of an acid acceptor such as triethylamine. Hex-5-ynoic acid in turn can be prepared, for example, by alkaline hydrolysis of 5-cyanopent-1-yne.

Dimethyl N-acryloyl-L-glutamate, dimethyl N-(pent-­4-ynoyl)-L-glutamate, dimethyl N-(but-3-ynoyl)-L-glu­tamate, and dimethyl N-(hept-6-enoyl)-L-glutamate are obtained similarly from the acid chlorides of acrylic acid, pent-4-ynoic acid, but-3-ynoic acid, and hept-6-­enoic acid, respectively, and dimethyl L-glutamate.

EXAMPLE 2

Dimethyl N-[6-(2-Pivaloylamino-4-hydroxy-5,6,7,8-tetra­hydropyrido[2,3-d]pyrimidin-6-yl)hexanoyl]-L-glutamate

To a solution of 1.0g of dimethyl N-[6-(2-pival­oylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-yl)hex-5-­ynoyl]-L-glutamate in 20mL. of glacial acetic acid were added 300 mg. of platinum oxide. The mixture was hy­drogenated under one atmosphere pressure with agitation for 4 hours, the catalyst removed by filtration, and the filtrate concentrated under reduced pressure. Chromatography on silica gel eluting with 1:19 methanol:chloroform yielded 0.84g. (82.7%) of dimethyl N-[6-(2-pivaloylamino-4-hydroxy-5,6,7,8-tetrahydro­pyrido[2,3-d]pyrimidin-6-yl)hexanoyl]-L-glutamate, m.p. 162-166^oC. Anal. Calc. for C₂₅H₃₉N₅O₇: C, 57.57; H, 7.54; N, 13.43. Found: C, 57.31; H, 7.25; N, 14.15.

Similarly prepared from dimethyl N-[5-(2-pival­oylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-yl)pent-4-­ynoyl]-L-glutamate is dimethyl N-[5-(2-pivaloylamino-4-­hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl)pentanoyl]-L-glutamate. In a representative experi­ment, the following physical constants were obtained for this compound: m.p. 151-159^oC; Anal. Calc. for C₂₄H₃₇N₅O₇: C, 56.79; H, 7.35; N, 13.80. Found: C, 57.06; H, 7.22; N, 13.86.

Likewise dimethyl N-[3-(2-pivaloylamino-4-hydroxy-­5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)propion­yl]-L-glutamate and dimethyl N-[4-(2-pivaloylamino-4-­hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)­butyryl]-L-glutamate are prepared from N-[3-(2-pival­oylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-yl)acryl­oyl]-L-glutamate and dimethyl N-[4-(2-pivaloylamino-4-­hydroxypyrido[2,3-d]pyrimidin-6-yl)but-3-ynoyl]-L-glu­tamate, respectively.

By utilizing an equivalent amount of dimethyl N-­[7-(2-pivaloylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-­yl)hept-6-enoyl]-L-glutamate, there is obtained di­methyl N-[7-(2-pivaloylamino-4-hydroxy-5,6,7,8-tetra­hydropyrido[2,3-d]pyrimidin-6-yl)heptanoyl]-L-glutamate In a representative experiment, the following physical constants were obtained for this compound: m.p. 152-­160^oC. Anal. Calc. for C₂₆H₄₁N₅O₇: C, 58.30; H, 7.72; N, 13.08. Found: C, 58.51; H, 7.61; N, 12.87.

EXAMPLE 3

Diethyl N-[4-{2-(2-Pivaloylamino-4-hydroxy-5,6,7,8-­tetrahydropyrido[2,3-d]pyrimidin-6-yl)ethyl}cyclohex-­1-yl]-L-glutamate

A. Five grams of 2-pivaloylamino-4-hydroxy-6-(4-­carboxyphenylethynyl)pyrido[2,3-d]pyrimidine (described in European Patent Application 87308921.3) and 1.60g. of platinum oxide in 200mL. of trifluoroacetic acid were hydrogenated in a Parr apparatus at ambient tem­perature and 60 psi for 24 hours. Removal of the cata­lyst by filtration and concentration of the filtrate yielded 2-pivaloylamino-4-hydroxy-6-[2-(4-carboxycyclo­ hex-1-yl)ethyl]-5,6,7,8-tetrahydropyrido[2,3-d]pyrim­idine as a white solid which was further purified by column chromatography (Waters 200) eluting with 1:9 methanol:dichloromethane. m.p. 218-234^oC. Anal. Calc. for C₂₁H₃₂N₄O₄: C, 63.35; H, 7.97; N, 13.85. Found: C, 63.30; H, 7.48; N, 13.57.

B. To a solution of 2.40g. of 2-pivaloylamino-4-­hydroxy-6-[2-(4-carboxycyclohex-1-yl)ethyl]-5,6,7,8-­tetrahydropyrido[2,3-d]pyrimidine in 50mL. of dry N-­methylpyrrolidone and 2.25mL. of N-methylmorpholine were added 2.75g. of phenyl N-phenylphosphoamino­chloridate. This mixture was stirred at 0^oC under nitrogen for 45 minutes and 2.45g. of diethyl L-gluta­mate were then added and stirring at ambient tempera­tures then was continued for 72 hours. The solvent was removed by distillation at 0.2mm/60^oC and the residue chromatographed on silica gel, eluting with 1:19 methanol:chloroform to yield 1.67g. (48%) of diethyl N-­[4-{2-(2-pivaloylamino-4-hydroxy-5,6,7,8-tetrahydro­pyrido[2,3-d]pyrimidin-6-yl)ethyl}cyclohex-1-yl]-L-glu­tamate, m.p. 160-170^oC. Anal. Calc. for C₃₀H₄₇N₅O₇: C, 61.10; H, 8.03; N, 11.87. Found: C, 61.38; H, 7.90; N, 11.84.

EXAMPLE 4

N-[6-(2-Amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-­d]pyrimidin-6-yl)hexanoyl]-L-glutamic Acid

A solution of 0.5g. of dimethyl N-[6-(2-pivaloyl­amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrim­idin-6-yl)hexanoyl]-L-glutamate in 75mL. of 1.0 N aqueous sodium hydroxide is stirred at room temperature for 120 hours and the pH then adjusted to 7.0 through the careful addition of 5.0 N hydrochloric acid. Water was removed under reduced pressure and the concentrated solution then cooled in an ice-bath. The solid which formed was collected by filtration and dried at 80^oC to yield N-[6-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido­[2,3-d]pyrimidin-6-yl)hexanoyl]-L-glutamic acid, m.p. foaming at 135^oC, melting at 180-195^oC. NMR (DMSO-d₆ 300 MHz) delta: 9.80 (s, br, 1H), 7.90 (s, J=8 Hz, 1H), 6.20 (s, 1H), 5.95 (s, 2H), 4.08 (m, 1H), 3.10 (m, 1H), 2.63 (t, J=10 Hz, 1H), 2.40 (m, 1H), 2.20 (t, J=8 Hz, 2H), 2.05 (t, J=8 Hz, 2H), 1.84 (m, 1H), 1.70 (m, 2H), 1.55 (m, 3H), 1.20 (m, 6H).

Similarly prepared from dimethyl N-[5-(2-pival­oylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]­pyrimidin-6-yl)pentanoyl]-L-glutamate is N-[5-(2-amino-­4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl)pentanoyl]-L-glutamic acid. In a representative ex­periment, the following physical constants were ob­tained for this compound: m.p. 144^oC (softening and foaming); NMR (DMSO-d₆ 300 MHz) delta: 9.70 (s, br, 1H), 8.01 (d, J=6 Hz, 1H), 6.17 (s, 1H), 5.88 (s, 2H), 4.13 (m, 1H), 3.17 (m, 1H), 2.68 (t, J=6 Hz, 1H), 2.42 (m, 1H), 2.22 (t, J=5 Hz, 2H), 2.07 (t, J=5 Hz, 2H), 1.88 (m, 1H), 1.70 (m, 2H), 1.44 (m, 3H), 1.24 (m, 4H);

N-[3-(2-Amino-4-hydroxy-5,6,7,8-tetrahydropyrido­[2,3-d]pyrimidin-6-yl)propionyl]-L-glutamic acid and N-­[4-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]­pyrimidin-6-yl)butyryl]-L-glutamic acid are prepared analogously from dimethyl N-[3-(2-pivaloylamino-4-­hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-­yl)propionyl]-L-glutamate and dimethyl N-[4-(2-­pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-­d]pyrimidin-6-yl)butyryl]-L-glutamate, respectively.

In a similar fashion, N-[7-(2-Amino-4-hydroxy-­5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)heptan­oyl]-L-glutamic acid is prepared from dimethyl N-[7-(2-­pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyrido­[2,3-d]pyrimidin-6-yl)heptanoyl]-L-glutamate. In a representative experiment, the following physical con­stants were obtained for this compound: m.p. 185-195^oC (foaming); NMR (DMSO-d₆ 300 MHz) delta: 9.68 (s, br, 1H), 8.01 (d, J=10 Hz, 1H), 6.20 (s, 1H), 5.88 (s, 2H), 4.14 (m, 1H), 3.10 (m, 1H), 2.66 (t, J=9 Hz, 1H), 2.35 (m, 1H), 2.20 (t, J=5 Hz, 2H), 2.05 (t, J=5 Hz, 2H), 1.89 (m, 1H), 1.67 (m, 2H), 1.45 (m, 3H), 1.20 (m, 8H).

Analogously by employing diethyl N-[4-{2-(2-pival­oylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]­pyrimidin-6-yl)ethyl}cyclohex-1-yl]-L-glutamate, there is obtained N-[4-{2-(2-amino-4-hydroxy-5,6,7,8-tetra­hydropyrido[2,3-d]pyrimidin-6-yl)ethyl}cyclohex-1-yl]-­L-glutamic acid. In a representative experiment, the following physical constants were obtained for this compound: m.p. 210-225^oC. NMR (DMSO-d₆ 300 MHz) delta: 9.70 (s, br, 1H), 7.90 (m, 1H), 6.23 (s, 1H), 5.92 (s, 2H), 4.17 (m, 1H), 3.18 (m, 1H), 2.72 (t, J=9 Hz, 1H), 2.45 (m, 1H), 2.27 (t, J=6 Hz, 2H), 2.09 (m, 1H), 1.96 (m, 1H), 1.74 (m, 3H), 1.45 (m, 5H), 1.27 (m, 8H).

EXAMPLE 5

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

A. A solution of 1.50g. (7.25 mmol.) of 5-bromo-2-­thiophenecarboxylic acid, several drops of dimethyl­formamide, and 2.21mL. of thionyl chloride was heated at reflux for 2.5 hours. The solvent was removed under reduced pressure and the residue redissolved in 10mL. of dry methylene chloride. This solution was added dropwise to an ice-cooled solution of 1.62g. of di­methyl L-glutamate hydrochloride, 10 mg. of dimethyl­aminopyridine, and 2.11mL. of triethylamine in 25mL. of dry methylene chloride. When the addition was complete, the mixture was stirring at ambient tempera­tures for 12 hours and then diluted with water and ex­tracted with methylene chloride. The organic extracts were washed with 1.0 N hydrochloric acid and saturated sodium bicarbonate solution and then evaporated to yield 2.71g. (100%) of dimethyl N-[5-bromothien-2-yl-­carbonyl]-L-glutamate as a viscous oil which can be used in the following procedure without further purifi­cation.

Dimethyl N-[5-bromofur-2-ylcarbonyl]-L-glutamate, also a viscous oil, is prepared analogiusly from 5-­bromo-2-furancarboxylic acid.

Dimethyl N-(5-bromothien-3-ylcarbonyl)-L-glutamate can be prepared in a similar fashion from 5-bromo-3-­thienylcarboxylic acid.

B. A mixture of 1.70g. (6.32 mmol.) of 2-pivaloyl­amino-4-hydroxy-6-ethynylpyrido[2,3-d]pyrimidine, 2.30g. (6.32 mmol.) of dimethyl N-(5-bromothien-2-yl-­carbonyl)-L-glutamate, 44mg. of palla-dium chloride, 130mg. of triphenylphosphine, 25mg. of cuprous iodide, and 1.13mL. of triethylamine in 30mL. of acetonitrile was heated at reflux for 3 hours and then cooled to am­bient temperature. The solvent was removed under re­duced pressure and the residue column chromatographed (Waters 500) eluting with 1:19 methanol:methylene chlo­ride to yield dimethyl N-[5-(2-pival-oylamino-4-­hydroxypyrido[2,3-d]pyrimidin-6-yl}ethynyl)thien-2yl-­carbonyl]-L-glutamate, m.p. 228-230^oC. Anal. Calc. for C₂₆H₂₇N₅O₇S: C, 56.41; H, 4.92; N, 12.65; S, 5.79. Found: C, 56.64; H, 4.77; N, 12.88; S, 5.58.

In as similar fashion by substituting an equiva­lent amount of dimethyl N-(5-bromofur-2-ylcarbonyl)-L-­glutamate for dimethyl N-(5-bromothien-2-ylcarbonyl)-L-­glutamate in the foregoing procedure, there can be ob­tained dimethyl N-[5-(2-pivaloylamino-4-hydroxypyrido­[2,3-d]pyrimidin-6-yl}ethynyl)fur-2ylcarbonyl]-L-glu­tamate. In a representative experiment, the following physical constants were obtained for this compound: m.p. 135^oC (darkens), 181^oC (decomposition). Anal. Calc. for C₂₆H₂₅N₅O₈: C, 58.32; H, 4.71; N, 13.08. Found: C, 58.58; H, 4.92; N, 13.11.

Likewise by substituting an equivalent amount of dimethyl N-(5-bromothien-3-ylcarbonyl)-L-glutamate for dimethyl N-(5-bromothien-2-ylcarbonyl)-L-glutamate in the foregoing procedure, there can be obtained dimethyl N-[5-(2-pivaloylamino-4-hydroxypyrido[2,3-d]pyrimidin-­6-yl}ethynyl)thien-3-ylcarbonyl]-L-glutamate.

EXAMPLE 6

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

To a solution of 0.5g. of dimethyl N-[5-(2-pival­oylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-yl}ethyn­yl)thien-2ylcarbonyl]-L-glutamate in 30mL. of glacial acetic acid were added 1.5g. of 5% palladium on carbon. The mixture was hydrogenated under one atmosphere pres­sure with agitation for 18 hours, the catalyst removed by filtration, and the filtrate concentrated under re­duced pressure. Chromatography on silica gel eluting with 1:19 methanol:chloroform yielded 100mg. (19.7%) of dimethyl N-[5-(2-{2-pivaloylamino-4-hydroxypyrido[2,3-­d]pyrimidin-6-yl}ethyl)thien-2-ylcarbonyl]-L-glutamate, and 204mg. (40.2%) of the desired dimethyl N-[5-(2-{2-­pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-­d]pyrimidin-6-yl}ethyl)thien-2-ylcarbonyl]-L-glutamate, m.p. 152-160^oC. Anal. Calc. for C₂₆H₃₅N₅O₇S: C, 55.60; H, 6.28; N, 12.47. Found: C, 55.76; H, 6.23; N, 12.26. The partially hydrogenated by-product can be rehydro­genated to yield additional final product.

Similarly prepared from dimethyl N-[5-(2-pival­oylamino-4-hydroxypyrido[2,3-d]pyrimidin-6-yl}ethynyl)­fur-2ylcarbonyl]-L-glutamate is dimethyl N-[5-(2-{2-­pivaloylamino-4-hydroxy-5,6,7,8-tetrahydropyrido­[2,3-d]pyrimidin-6-yl}ethyl)fur-2-ylcarbonyl]-L-gluta­mate. In a representative experiment, the following physical constants were obtained for this compound: m.p. 155-162^oC; Anal. Calc. for C₂₆H₃₃N₅O8: C, 57.45; H, 6.12; N, 12.88. Found: C, 57.22; H, 6.08; N, 12.66.

Likewise dimethyl N-[5-(2-{2-pivaloylamino-4-hydr­oxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}­ethyl)thien-3-ylcarbonyl]-L-glutamate can be prepared from dimethyl N-[5-(2-pivaloylamino-4-hydroxypyrido­[2,3-d]pyrimidin-6-ylethynyl)thien-3-ylcarbonyl]-L-glu­tamate.

EXAMPLE 7

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

A solution of 100mg. of dimethyl N-[5-(2-{2-pival­oylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]­pyrimidin-6-yl}ethyl)thien-2-ylcarbonyl]-L-glutamate in 15mL. of 1.0 N aqueous sodium hydroxide is stirred at room temperature for 120 hours and the pH then adjusted to 7.0 through the careful addition of 5.0 N hydro­chloric acid. The solid which formed was collected by filtration and dried at 80^oC to yield 61.5mg (76.8%) of N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido­[2,3-d]pyrimidin-6-yl}ethyl)thien-2-ylcarbonyl]-L-glu­tamic acid, m.p. 226-240^oC. (foaming and decomposi­tion). NMR (DMSO-d₆ 300 MHz) delta: 9.80 (s, br, 1H), 8.45 (d, J=9 Hz, 1H), 7.62 (d, J=3 Hz, 1H), 6.87 (d, J=3 Hz, 1H), 6.30 (s, 1H), 6.04 (s, 2H), 4.28 (m, 1H), 3.12 (m, 1H), 2.84 (m, 3H), 2.36 (m, 1H), 2.02 (m, 1H), 1.83 (m, 2H), 1.57 (m, 3H).

Similarly prepared from dimethyl N-[5-(2-{2-pival­oylamino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyri­midin-6-yl}ethyl)fur-2-ylcarbonyl]-L-glutamate is N-[5-­(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]­pyrimidin-6-yl}ethyl)fur-2-ylcarbonyl-L-glutamic acid. In a representative experiment, the fol-lowing physical constants were obtained for this compound: m.p. 204-­230^oC. (foaming). NMR (DMSO-d₆ 300 MHz) delta: 9.80 (s, br, 1H), 8.27 (d, J=9 Hz, 1H), 7.03 (d, J=4 Hz, 1H), 6.30 (s, 1H), 6.25 (d, J=4 Hz, 1H), 6.04 (s, 2H), 4.30 (m, 1H), 3.16 (m, 1H), 2.65 (m, 3H), 2.42 (m, 1H), 2.16 (t, J=7Hz, 2H), 2.01 (m, 1H), 1.84 (m, 2H), 1.57 (m, 3H).

N-[5-(2-{2-Amino-4-hydroxy-5,6,7,8-tetrahydro­pyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-3-ylcarbonyl]-­L-glutamic acid can be prepared similarly from dimethyl N-[5-(2-{2-pivaloylamino-4-hydroxy-5,6,7,8-tetrahydro­pyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-3-ylcarbonyl]-­L-glutamate.

EXAMPLE 8

The IC₅₀ in whole cell human leukemia cell lines, CCRF-CEM, of N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetra­hydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-ylcarbo­nyl]-L-glutamic acid is 0.0015 ug/mL. The IC₅₀ of N-­[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-­d]pyrimidin-6-yl}ethyl)fur-2-ylcarbonyl]-L-glutamic acid is 0.010 ug/mL. The IC₅₀ of N-[4-(2-{2-amino-4-­hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}­ethyl)thien-2-ylcarbonyl]-L-glutamic acid is 0.0756 ug/mL.

The IC₅₀ in whole cell human leukemia cell lines, CCRF-CEM, of other compounds of this invention are as follows: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="5" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="31.50mm" /><colspec colnum="2" colname="col2" colwidth="31.50mm" /><colspec colnum="3" colname="col3" colwidth="31.50mm" /><colspec colnum="4" colname="col4" colwidth="31.50mm" /><colspec colnum="5" colname="col5" colwidth="31.50mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col1" align="center">R¹</entry><entry namest="col2" nameend="col2" align="center">R²</entry><entry namest="col3" nameend="col3" align="left">R³</entry><entry namest="col4" nameend="col4" align="center">R⁴</entry><entry namest="col5" nameend="col5" align="center">ug/mL</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">OH</entry><entry namest="col2" nameend="col2" align="left">H</entry><entry namest="col3" nameend="col3" align="left">-(CH₂)₂-</entry><entry namest="col4" nameend="col4" align="left">H</entry><entry namest="col5" nameend="col5" align="char" char=".">0.023</entry></row><row><entry namest="col1" nameend="col1" align="left">OH</entry><entry namest="col2" nameend="col2" align="left">H</entry><entry namest="col3" nameend="col3" align="left">-(CH₂)₃-</entry><entry namest="col4" nameend="col4" align="left">H</entry><entry namest="col5" nameend="col5" align="char" char=".">0.0075</entry></row><row><entry namest="col1" nameend="col1" align="left">OH</entry><entry namest="col2" nameend="col2" align="left">H</entry><entry namest="col3" nameend="col3" align="left">-(CH₂)₄- CH₂-CH₂</entry><entry namest="col4" nameend="col4" align="left">H</entry><entry namest="col5" nameend="col5" align="char" char=".">0.034</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">OH</entry><entry namest="col2" nameend="col2" align="left">H</entry><entry namest="col3" nameend="col3" align="left">-CH CH- CH₂-CH₂</entry><entry namest="col4" nameend="col4" align="left">H</entry><entry namest="col5" nameend="col5" align="char" char=".">0.007</entry></row></tbody></tgroup></table></tables>

<u style="single">In vivo</u> evaluation against various neoplasms pro­duced the following values: <tables id="tabl0002" num="0002"><img file="EP0343801A2_D0015.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP0343801A2_D0016.tif" /></tables><tables id="tabl0004" num="0004"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(b.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">6C3HED lymphosarcoma tumors in mice: (IP, daily administration, 10 days)</entry></row><row><entry namest="col1" nameend="col1" align="left">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="char" char=".">6.25</entry><entry namest="col2" nameend="col2" align="left">toxic</entry><entry namest="col3" nameend="col3" align="right">10/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">3.12</entry><entry namest="col2" nameend="col2" align="right">100</entry><entry namest="col3" nameend="col3" align="right">6/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">1.56</entry><entry namest="col2" nameend="col2" align="right">100</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="char" char=".">0.78</entry><entry namest="col2" nameend="col2" align="right">93</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0005" num="0005"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(c.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">B-16 Melanoma tumors in mice: (IP, daily administration, days 1, 7)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">200</entry><entry namest="col2" nameend="col2" align="right">93</entry><entry namest="col3" nameend="col3" align="right">4/10</entry></row><row><entry namest="col1" nameend="col1" align="right">100</entry><entry namest="col2" nameend="col2" align="right">73</entry><entry namest="col3" nameend="col3" align="right">3/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">50</entry><entry namest="col2" nameend="col2" align="right">38</entry><entry namest="col3" nameend="col3" align="right">0/9</entry></row></tbody></tgroup></table></tables><tables id="tabl0006" num="0006"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(d.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">C3H Mammary Adenocarcinoma tumors in mice: (IP, daily administration, days 1, 4, 7, 10)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="char" char=".">40</entry><entry namest="col2" nameend="col2" align="right">100</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">20</entry><entry namest="col2" nameend="col2" align="right">100</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">10</entry><entry namest="col2" nameend="col2" align="right">94</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">5</entry><entry namest="col2" nameend="col2" align="right">90</entry><entry namest="col3" nameend="col3" align="right">1/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="char" char=".">2.5</entry><entry namest="col2" nameend="col2" align="right">71</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0007" num="0007"><table frame="all"><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(e.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">CA-755 Adenocarcinoma tumors in mice: (IP, daily administration, days 1, 4, 7, 10)</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row rowsep="1"><entry namest="col1" nameend="col1" align="right">40</entry><entry namest="col2" nameend="col2" align="right">83</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">20</entry><entry namest="col2" nameend="col2" align="right">78</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0008" num="0008"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(f.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">CX-1 Colon Xenography in mice: (IP, daily administration, days 1, 4, 7, 10)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">40</entry><entry namest="col2" nameend="col2" align="left">toxic</entry><entry namest="col3" nameend="col3" align="right">10/10</entry></row><row><entry namest="col1" nameend="col1" align="right">20</entry><entry namest="col2" nameend="col2" align="right">91</entry><entry namest="col3" nameend="col3" align="right">9/10</entry></row><row><entry namest="col1" nameend="col1" align="right">10</entry><entry namest="col2" nameend="col2" align="right">94</entry><entry namest="col3" nameend="col3" align="right">6/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">5</entry><entry namest="col2" nameend="col2" align="right">90</entry><entry namest="col3" nameend="col3" align="right">3/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0009" num="0009"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(g.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">LX-1 Lung Xenography in mice: (IP, daily administration, days 1, 4, 7, 10)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">40</entry><entry namest="col2" nameend="col2" align="left">toxic</entry><entry namest="col3" nameend="col3" align="right">8/8</entry></row><row><entry namest="col1" nameend="col1" align="right">20</entry><entry namest="col2" nameend="col2" align="right">100</entry><entry namest="col3" nameend="col3" align="right">4/8</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">10</entry><entry namest="col2" nameend="col2" align="right">98</entry><entry namest="col3" nameend="col3" align="right">0/8</entry></row></tbody></tgroup></table></tables><tables id="tabl0010" num="0010"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(h.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)thien-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">MX-1 Mammary Xenography in mice: (IP, daily administration, days 1, 4, 7, 10)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">40</entry><entry namest="col2" nameend="col2" align="left">toxic</entry><entry namest="col3" nameend="col3" align="right">10/10</entry></row><row><entry namest="col1" nameend="col1" align="right">20</entry><entry namest="col2" nameend="col2" align="left">toxic</entry><entry namest="col3" nameend="col3" align="right">9/9</entry></row><row><entry namest="col1" nameend="col1" align="right">10</entry><entry namest="col2" nameend="col2" align="right">96</entry><entry namest="col3" nameend="col3" align="right">5/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">5</entry><entry namest="col2" nameend="col2" align="right">84</entry><entry namest="col3" nameend="col3" align="right">3/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0011" num="0011"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(i.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)fur-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">6C3HED lymphosarcoma tumors in mice: (IP, daily administration, eight days)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">100</entry><entry namest="col2" nameend="col2" align="right">89</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="right">50</entry><entry namest="col2" nameend="col2" align="right">69</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="right">25</entry><entry namest="col2" nameend="col2" align="right">59</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0012" num="0012"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(j.) N-[5-(2-{2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl}ethyl)fur-2-yl-carbonyl]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">6C3HED lymphosarcoma tumors in mice: (IP, daily administration, days 1, 4, 7)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="char" char=".">20</entry><entry namest="col2" nameend="col2" align="right">100</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">10</entry><entry namest="col2" nameend="col2" align="right">100</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">5</entry><entry namest="col2" nameend="col2" align="right">97</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">2.5</entry><entry namest="col2" nameend="col2" align="right">98</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">1.25</entry><entry namest="col2" nameend="col2" align="right">29</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="char" char=".">0.625</entry><entry namest="col2" nameend="col2" align="right">1</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0013" num="0013"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(k.) N-[4-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)butyryll]-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">6C3HED lymphosarcoma tumors in mice: (IP, daily administration, eight days)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="char" char=".">50</entry><entry namest="col2" nameend="col2" align="right">98</entry><entry namest="col3" nameend="col3" align="right">1/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">25</entry><entry namest="col2" nameend="col2" align="right">88</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">12.5</entry><entry namest="col2" nameend="col2" align="right">62</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">6.25</entry><entry namest="col2" nameend="col2" align="right">11</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="char" char=".">3.12</entry><entry namest="col2" nameend="col2" align="right">0</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row></tbody></tgroup></table></tables><tables id="tabl0014" num="0014"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="0"><entry namest="col1" nameend="col3" align="left">(l.) N-{4-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)ethyl]cyclohexylcarbonyl}-L-glutamic acid</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">6C3HED lymphosarcoma tumors in mice: (IP, daily administration, eight days)</entry></row><row><entry namest="col1" nameend="col1" align="center">Dose mg/kg</entry><entry namest="col2" nameend="col2" align="center">% Inhibition</entry><entry namest="col3" nameend="col3" align="center">Toxicity</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="char" char=".">100</entry><entry namest="col2" nameend="col2" align="right">22</entry><entry namest="col3" nameend="col3" align="right">0/9</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">50</entry><entry namest="col2" nameend="col2" align="right">5</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row><entry namest="col1" nameend="col1" align="char" char=".">25</entry><entry namest="col2" nameend="col2" align="right">4</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="char" char=".">12.5</entry><entry namest="col2" nameend="col2" align="right">18</entry><entry namest="col3" nameend="col3" align="right">0/10</entry></row></tbody></tgroup></table></tables>