This work was supported by research grant RO1-AI29904 from the National Institute of Allergy and Infectious Diseases (NIAID), U. S. Department of Health and Human Services. The government has certain rights in the invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides new compounds which are active dihydrofolate reductase (DHFR) inhibitors, more particularly, the compounds of the invention selectively inhibit activity of DHFR enzymes from parasitic organisms such as Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma). The present Invention further provides therapeutic methods of treating patients suffering from or susceptible to parasitic infections.

2. Background Piritrexim (A), a lipophilic inhibitor of the key metabolic enzyme dihydrofolate reductase (DHFR) has been studied intensively as an anticancer drug, and more recently was identified as a potent inhibitor of the enzyme from Pneumocystis cariiiii (Pc) and Toxoplasma gondii (Tg), two opportunistic parasites known to be potentially life-threatening in patients with acquired immunodeficiency syndrome (AIDS). See, for example, Grivsky, E. M.; Lee, S.; Sigel, C. W.; Duch, D.

S.; Nichol, C. A. J. Med Chem. 1980; 23,327-329 ; Sigel, C. W.; Macklin, A. W.; Woolley, J. L. , Jr.; Johnson N. W.; Collier, M. A.; Blum, M. R.; Clendeninn, N. J.; Everitt, J. M.; Grebe, G.; Mackars, A.; Foss, R. G.; Duch, D. S.; Bowers, S. W.; Nichol, C. A. NCIMonogr. 1987; 5, 111-120; Laszlo, J.; Brenckman, W. D. , Jr.; Morgan, E.; Clendeninn, N. J.; Williams, T.; Currie, V.; Young, C. NCIMonogr.

1987; 5, 121-125; and Kovacs, J.; Allegra, C. A.; Swan, J. C.; Drake, J. C.; Parrillo, J.

E.; Chabner, B. A.; Masur, H. Antimicrob. Agents Che7nother. 1988; 32,430-433. A notable structural feature of (A) is the short CH2 bridge between the two halves of the molecule. This bridge is also present in trimethoprim (B), another lipophilic DHFR inhibitor widely used to for anti-Pc and anti-Tg prophylaxis and therapy in AIDS patients, usually in combination with a sulfa drug to enhance efficacy. For an excellent historical account of the chemical and pharmaceutical development of the older lipophilic DHFR inhibitors pyrimethamine and trimethoprim, see: Roth, B.; Cheng, C. C. Progr. Med Chem. 1982 ; 19, 269-331 ; Fischl, M. A.; Dickinson, G. M.; La Voie, L. J Am. Med. Assoc. 1988; 259,1185-1189 ; and Medina, I.; Mills, J.; Leoung, G.; Hopewell, P. C.; Lee, B.; Modin, G.; Benowitz, N.; Wofsy, C. B. N.

Engl. J. Med 1990; 323,776-782. Two other members of this class that have been used clinically against these infections are pyrimethamine (C), in which the two halves of the molecule are linked without a CH2 bridge, and trimetrexate (D), which contains a longer CH2NH bridge. In addition to the fact that it contains a longer bridge, (D) differs from (A) in being a quinazoline as opposed to a pyrido [2,3- d] pyrimidine. See for example, Bertino, J. R.; Sawicki, W. L.; Moroson, B. A.; Cashmore, A. R.; Elslager, E. F. Biochem. Pharmacol. 1979; 28, 1983-1987; Elslager, E. F.; Johnson, E. L.; Werbel, L. M. J. Med Chem. 1983 ; 26, 1753-1760; and Sattler, F. R.; Frame, P.; Davis, R.; Nichols, L.; Shelton, B.; Akil, B.; Baugman, R.; Hughlett, C.; Weiss, W.; Boylen, C. T.; van der Horst, C.; Black, J.; Masur, H.; Feinberg, J. J.

Infect. Dis. 1994; 170, 165-172.

There has been reported examples of certain lipophilic DHFR inhibitors in which the fused 2,4-diaminopyrimidine ring system and the aryl side chain are separated by a short O or S bridge, as in (E) and (F). The only quinazoline antifolates reported to date, however, are those in which the bridge is CH2 are the 5,6, 7,8- tetrahydro derivatives (G). See for example Elslager, E. F.; Clarke, J.; Johnson, J.; Werbel, L. M. Davoll, J. J. Heterocycl. Chem. 1972; 9, 759-773; Hynes, J. B.; Ashton, W. T.; Merriman, H. G., III, Walker, F. C. , III. J. Med Chem. 1974; 17, 682- 684; and Rosowsky A; Papoulis, A. T.; Forsch, R. A.; Queener, S. F. J. Med Chem.

1999; 42, 1007-1017.

International application PCT/US02/37155, filed November 19,2002, to Rosowsky et al recites a related class of compounds having a heterocylic ring. structure and a phenyl group linked by a methylene group where the phenyl or naphthyl group may be substituted with a variety of substituents.

It would be desirable to have new methods for synthesis of biologically active DHFR inhibitors such as compounds (A) - (G) and the like.

SUMMARY OF THE INVENTION The present invention provides a new class of compounds possessing selective binding affinities to parasitic dihydrofolate reductase enzymes (DHFR). More particularly, the compounds of the invention selectively bind to at least one parasitic DHFR enzyme with greater binding affinity than mammalian DHFR enzymes such as DHFR from rat, primates or human. Compounds of the invention typically possess at least one lipophilic, e. g. , hydrophobic, substituent which is functionalized with an acidic residue. The acid functionalized hydrophobic substituent is suitable for binding to a hydrophobic channel present in mammalian and parasitic DHFR enzymes.

Although not wishing to be bound by theory, it is believed that a basic residue present in the hydrophobic channel of parasitic DHFR enzymes results in the compounds of the invention which possess an acid functionalized hydrophobic substituent having a higher affinity for parasitic DHFR enzymes relative to other DHFR enzymes including mammalian DHFR enzymes.

The present invention provides compounds of the formula: wherein HET is selected from RA is independently selected at each occurrence of RA from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di- alkylamino, and nitro; or two adjacent RA groups taken in combination from a group of the formula: which may be optionally substituted; R is L- (CR'R2)"-C (O)-X or a group of the formula:

L is a single bond, an optionally substituted 1,2-vinylidene group, or a 1,2 acetylene-diyl group; X is selected from OH, SH, NH2, optionally substituted alkoxy, optionally substituted benzyloxy, or optionally substituted aryloxy and salts thereof; and Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof; Z is a single bond or hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; n is an integer of from 0 to about 12, wherein the sum of n and the number of carbon atoms in the hydrocarbon chain of the Z group is greater than 0; i is an integer from 0 to about 4; j is an integer from 0 to about 5; and Rl, R2, R3 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Preferred compounds of Formula I are DHFR inhibitors and more preferably selectively inhibit DHFR activity in parasitic organisms. Thus preferred compounds of the invention are capable of selectively inhibiting DHFR in parasitic organisms with minimal or no disruption of DHFR activity in the host organism.

The present invention further provides pharmaceutical compositions comprising a pharmaceutically acceptable carrier and at least one compound according to Formula I or any subformula thereof.

Methods of treating a patient, e. g. , a mammalian patient, who is suffering from or is susceptible to a parasitic invention are also provided by the present invention.

Typically a pharmaceutically effective dose of at least one compound according to Formula I or a subformula thereof is administered to the patient in need to prevent or ameliorate the effects of a parasitic infection.

Other aspects of the of the invention are discussed infra.

DETAILED DESCRIPTION OF THE INVENTION Preferred compounds of the invention include those compounds according to one of Formula II or Formula III:

wherein RA is independently selected at each occurrence of RA from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di- alkylamino, and nitro; or two adjacent RA groups taken in combination form a group of the formula: may be optionally substituted; R is L-(CRIR2) n-C (O)-X or a group of the formula:

L is a single bond, an optionally substituted 1, 2-vinylidene group, or a 1,2 acetylene-diyl group;

X is selected from OH, SH, NH2, optionally substituted alkoxy, optionally substituted benzyloxy, or optionally substituted aryloxy and salts thereof; and Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof; Z is a single bond or hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; n is an integer of from 0 to about 12, wherein the sum of n and the number of carbon atoms in the hydrocarbon chain of the Z group is greater than 0; i is an integer from 0 to about 4; j is an integer from 0 to about 5; and R'and R2 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Preferred compounds according to Formula II include those compounds represented by Formula IV: In certain preferred compounds of Formula IV, each occurrence of RA is an optionally substituted alkoxy group, or more preferably, each RA is a methoxy residue.

The invention further provides compounds according to Formula V and according to Formula VI:

wherein RA is independently selected at each occurrence of RA from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di- alkylamino, and nitro; or two adjacent RA groups taken in combination form a group of the formula: which may be optionally substituted; L is a single bond or a 1,2 acetylene-diyl group; X is selected from OH, SH, NH2, optionally substituted alkoxy, optionally substituted benzyloxy, or optionally substituted aryloxy and salts thereof; and n is an integer of from 1 to about 12; or i is an integer from 0 to about 4; j is an integer from 0 to about 5; and R and R2 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

In preferred compounds according to any one of Formula II, III, IV, V, and VI, the L group is either a single bond or a 1, 2-acetylenediyl group, i. e. , a C-C triple bond (-C=C-).

Yet other preferred compounds according to Formula III include those compounds represented by the structure:

Still other preferred compounds according to Formula II and Formula IV include those compounds represented by the structure:

wherein p is an integer of from 1 to 12 or from about 1 to about 10, or more preferably of from about 2 to about 8. In certain particularly preferred compounds, p is 2,3, or 4.

Other preferred compounds according to Formula III include those compounds represented by the structure:

wherein p is an integer from 3 to about 14.

Other preferred compounds of Formula II which are provided by the invention include those compounds represented by one of Formula VII, Formula VIII or Formula IX:

wherein RA is independently selected at each occurrence of RA from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di- alkylamino, and nitro; or two adjacent RA groups taken in combination form a group of the formula: which may be optionally substituted; Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof ; Z is a single bond or hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; n is an integer of from 0 to about 12, wherein the sum of n and the number of carbon atoms in the hydrocarbon chain of the Z group is greater than 0; i is an integer from 0 to about 4; j is an integer from 0 to about 5; and Rl and R2 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Preferred compounds according to Formula IX include those compounds in which: Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof;

Z is a single bond or hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; n is an integer of from 0 to about 12, wherein the sum of n and the number of carbon atoms in the hydrocarbon chain of the Z group is greater than 0; j is an integer from 0 to about 5; and Rl and R2 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Other particularly preferred compounds according to Formula IX include compounds according to the formula :,

wherein at least one Y3 and Y4 is a carboxylic acid residue or a salt thereof.

Other preferred compounds according to Formula II include those compounds according to Formula X:

wherein RA is selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally

substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di-alkylamino, and nitro; Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is CO2H or a salt thereof; Z is a hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; j is an integer from 0 to about 5; and Rl and R2 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Preferred compounds of Formula X provided by the invention include those compounds according to the formula: wherein at least one Y3 and Y4 is a carboxylic acid residue or a salt thereof; and p is an integer of from 1 to about 4.

Still other preferred compounds of Formula X provided by the invention include those compounds according to the formula:

wherein at least one Y3 and Y4 is a carboxylic acid residue or a salt thereof; and p is an integer of from 3 to about 6.

Other preferred compounds of the invention include those compounds according to any one of Formula XI, XII, or XIII:

wherein RA is independently selected at each occurrence of RA from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di- alkylamino, and nitro; or two adjacent RA groups taken in combination form a group of the formula:

which may be optionally substituted; R is L-(CRlR2) n-C (O)-X or a group of the formula: L is a single bond, an optionally substituted 1,2-vinylidene group, or a 1,2 acetylene-diyl group; W is a CH group or N; X is selected from OH, SH, NH2, optionally substituted alkoxy, optionally substituted benzyloxy, or optionally substituted aryloxy and salts thereof; and Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof; Z is a single bond or hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; n is an integer of from 0 to about 12, wherein the sum of n and the number of carbon atoms in the hydrocarbon chain of the Z group is greater than 0; i is an integer from 0 to about 4; j is an integer from 0 to about 5; and Rl, R2, R3 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Preferred compounds according to Formula XI provided by the present invention include those compounds according to any one of Formula XIV or XV:

wherein RA is independently selected at each occurrence of RA from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di- alkylamino, and nitro; or two adjacent RA groups taken in combination form a group of the formula: which may be optionally substituted; L is a single bond or a 1,2 acetylene-diyl group; W is a CH group or N; X is selected from OH, SH, NH2, optionally substituted alkoxy, optionally substituted benzyloxy, or optionally substituted aryloxy and salts thereof ; and n is an integer of from 1 to about 12; or i is an integer from 0 to about 4; j is an integer from 0 to about 5; and

R', R2, R3 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

In preferred compounds according to any one of Formula XII, XIII, XIV or XV, the L group is either a single bond or a 1,2-acetylenediyl group, i. e. , a C-C triple bond (-C=C-).

Particularly preferred compounds of the invention according to Formula XV include those compounds of the formula:

wherein p is an integer from 3 to about 14.

Still other particularly preferred compounds of the invention according to Formula XV include those compounds of the formula:

wherein p is an integer from 1 to about 12.

The invention further provides compounds according to Formula XI according to any one of Formula XVI, XVII, or XVIII:

wherein RA is independently selected at each occurrence of RA from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di- alkylamino, and nitro; or two adjacent RA groups taken in combination form a group of the formula: which may be optionally substituted; W is a CH group or N;

Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof; Z is a single bond or hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; n is an integer of from 0 to about 12, wherein the sum of n and the number of carbon atoms in the hydrocarbon chain of the Z group is greater than 0; i is an integer from 0 to about 4; j is an integer from 0 to about 5; and Ru, R2, R3 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Particularly preferred compounds according to Formula XVIII include those compounds where: W is a CH group or N; Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof; Z is a single bond or hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; n is an integer of from 0 to about 12, wherein the sum of n and the number of carbon atoms in the hydrocarbon chain of the Z group is greater than 0; j is an integer from 0 to about 5; and Rl, R2, R3 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Particularly preferred compounds according to Formula XVIII, which are provided by the invention, include compounds according to formula:

wherein at least one Y3 and Y4 is a carboxylic acid residue or a salt thereof.

In yet another embodiment, the invention provides compounds according to Formula XIX: wherein RA is selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxy, optionally substituted haloalkyl, chloro, fluoro, hydroxy, amino, optionally substituted mono and di-alkylamino, and nitro; W is a CH group or N; Y is independently selected at each occurrence from the group consisting of -C (O)-X, hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy, wherein at least one occurrence of Y is C02H or a salt thereof; Z is a hydrocarbon chain having from 1 to about 6 carbon atoms in the chain and between 0 and about 2 double or triple bonds in the chain; j is an integer from 0 to about 5; and

R', R2, R3 are independently selected at each occurrence from the group consisting of hydrogen, methyl, ethyl, chloro, fluoro, hydroxy, amino, trifluoromethoxy, or methoxy.

Particularly preferred compounds according to Formula XIX, which are provided by the invention, include compounds according to formula:

wherein at least one Y3 and Y4 is a carboxylic acid residue or a salt thereof; and p is an integer of from 1 to about 4.

The invention provides other particularly preferred compounds according to Formula XIX, including compounds according to formula:

wherein at least one Y3 and Y4 is a carboxylic acid residue or a salt thereof; and p is an integer of from 3 to about 6.

Non-limiting examples of preferred compounds include compounds of Formula I selected from the group consisting of : 2, 4-Diamino-5- [5'- (4-carboxy-1-butynyl)-2'-methoxy) benzyl] pyrimidine (Compound 2);

2, 4-Diamino-5- [5'- (4-carboxy-l-pentynyl)-2'-methoxy) benzyl] pyrimidine (Compound 3); 2, 4-Diamino-5- [5'- (6-carboxy-1-hexynyl)-2'-methoxy) benzyl] pyrimidine (Compound 4); 2, 4-Diamino-5- [5'- (4-carboxybutyl)-2'-methoxy) benzyl] pyrimidine (Compound 5); 2, 4-Diamino-5- [5'- (5-carboxypentyl)-2'-methoxy) benzyl] pyrimidine (Compound 6); 2, 4-Diamino-5- [5'- (6-carboxyhexyl)-2'-methoxy) benzyl] pyrimidine (Compound 7); 2, 4-Diamino-5- [2'-methoxy-5'- (3"-carboxybenzyloxy) benzylpyrimidine (Compound 8); 2, 4-Diamino-5- (2'-methoxy-5'- (4"-carboxybenzyloxy) benzylpyrimidine (Compound 9); 2, 4-Diamino-5- [2'-methoxy-5'- [3- (2"-carboxyphenoxy) propyn-l- yl] benzyl] pyrimidine (Compound 10); 2, 4-Diamino-5- [2'-methoxy-5'- [3- (3"-carboxyphenoxy)-1-propynyl] benzyl] pyrimidine (Compound 11); and 6- [5- (2, 4-Diamino-pyrimidin-5-ylmethyl)-2, 3-dimethoxy-phenyl] -hex-5-ynoic acid (Compound 49).

Particularly preferred compounds according to any one of Formula I through XIX including any subformulae thereof which are provided by the present invention are lipophilic inhibitors of dihydrofolate reductase. More preferably, the compounds of the invention are selective inhibitors of parasitic dihydrofolate reductase including, but not limited to, dihydrofolate reductase of one or more parasites selected from a Pneumocystis carinfi (Pc), Toxoplasma gondii (Tg), or a Mycobacterium avina (Ma).

Suitable halogen substituent groups or halide groups of compounds of the invention, including compounds of any one of Formula I through XIX and any subformulae thereof as defined above, include F, Cl, Br and I. Alkyl groups of compounds of the invention preferably have from 1 to about 12 carbon atoms, more preferably 1 to about 8 carbon atoms, still more preferably 1 to about 6 carbon atoms.

As used herein, the term alkyl unless otherwise modified refers to both cyclic and

noncyclic groups, although of course cyclic groups will comprise at least three carbon ring members. Straight or branched chain noncyclic alkyl groups are generally more preferred than cyclic groups, particularly branched chain groups such as isopropyl and t-butyl. Preferred alkenyl groups of compounds of the invention have one or more unsaturated linkages and from 2 to about 12 carbon atoms, more preferably 2 to about 8 carbon atoms, still more preferably 2 to about 6 carbon atoms. The term alkenyl as used herein refer to both cyclic and noncyclic groups, although straight or branched noncyclic groups are generally more preferred, particularly branched chain groups.

Preferred alkoxy groups of compounds of the invention include groups having one or more oxygen linkages and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.

Preferred thioalkyl groups of compounds of the invention include those groups having one or more thioether linkages and from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, and still more preferably 1 to about 6 carbon atoms.

Preferred aminoalkyl groups include those groups having one or more primary, secondary and/or tertiary amine groups, and from 1 to about 12 carbon atoms, more preferably 1 to about 8 carbon atoms, still more preferably 1 to about 6 carbon atoms.

Substituted and unsubstituted mono and dialkylamino groups are particularly preferred, especially where each alkyl chain of the group has from 1 to about 6 carbon atoms. Preferred alkylsulfoxide of compounds of the invention have one or more sulfoxide groups, more typically one sulfoxide group, and from 1 to about 12 carbon atoms, more preferably 1 to about 8 carbon atoms, still more preferably 1 to about 6 carbon atoms. Preferred sulfonoalkyl groups of compounds of the invention have one or more sulfono (SO2) groups, more typically one or two sulfono groups, and from 1 to about 12 carbon atoms, more preferably 1 to about 8 carbon atoms, still more preferably 1 to about 6 carbon atoms. Preferred alkanoyl groups of compounds of the invention include groups having one or more carbonyl groups, more typically one or two carbonyl groups, and from 1 to about 12 carbon atoms, more preferably 1 to about 8 carbon atoms, still more preferably 1 to about 6 carbon atoms. Preferred alkylcarboxyamino groups include those groups of the formula-NHCOOR where R is substituted or unsubstituted alkyl having from 1 to about 10 carbon atoms, more preferably 1 to about 6 carbon atoms. Suitable heteroaromatic groups of compounds of the invention contain one or more N, O or S atoms and include, e. g. , quinolinyl, pyridyl, pyrazinyl, indolyl, carbazoyl, furyl, pyrrolyl, thienyl, thiazolyl,

aminothioazole such as 2-aminothiazole, pyrazole, oxazolyl, imidazolyl, indolyl, benzofuranyl, benzothiazol and pyridonal including 2-pyridonals and 4-pyridonals, particularly pyridonal substituted at one or more ring positions by moieties such as hydroxy, alkanoyl such as acetate, alkylaminocarbonyl having from 1 to about 8 carbon atoms and alkoxycarbonyl having from 1 to about 8 carbon atoms. Suitable heteroalicyclic groups of compounds contain one or more N, O or S atoms and include, e. g. , aziridinyl, azetidinyl, tetrahydrofuranyl, tetrahydropyranyl, pyrrolidino, 1,2, 3,6-tetrahydropyridino, piperazino, piperidinyl, morpholino and thiomorpholino.

Substituted moieties of compounds of the invention, including substituted RA, RI, R2, R3, W, X, Y, and Z groups, may be substituted at one or more available positions by one or more suitable groups such as, e. g. , halogen such as fluoro, chloro, bromo and iodo; cyano; hydroxyl; nitro; alkyl groups including those groups having 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms, preferably noncyclic alkyl groups including branched chain groups such as isopropyl and t-butyl; alkenyl and alkynyl groups including groups having one or more unsaturated linkages and from 2 to about 12 carbon or from 2 to about 6 carbon atoms; alkylthio groups including those moieties having one or more thioether linkages and from 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms; and, in at least preferred aspects of the invention, alkoxy groups having those having one or more oxygen linkages and from 1 to about 12 carbon atoms or 1 to about 6 carbon atoms; and aminoalkyl groups such as groups having one or more N atoms (which can be present as primary, secondary and/or tertiary N groups) and from 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms.

The present invention provides a straightforward and versatile approach that can lend itself to the synthesis of a rich library of previously unknown biologically active DHFR inhibitors in which a substituted aryl group is linked directly to the 2,4- diamino heterocyclic moiety via a CH2 bridge. The present invention also provides a new class of biologically active compounds according to formula I which are active DHFR inhibitors.

Thus the compounds of the present invention, particularly compounds of any one of Formula I through XIX and any subformulae thereof are useful as

pharmaceuticals for the treatment of mammals, including humans, particularly for the treatment of mammals having immunodeficiency disorder and/or HIV positive, particularly a human suffering from or susceptible to AIDS. Compounds of the invention typically combat parasitic infections which are known to inflict HIV- positive or patients suffering from or susceptible to AIDS. Thus, the invention provides a method for the treatment of AIDS, in mammals including humans, the method comprising administration of an effective amount of one or more compounds of the invention in a pharmaceutically useful form, once or several times a day or other appropriate schedule, orally, rectally, parenterally (particularly intravenously), topically, etc.

For such treatment, the compounds of the invention are administered in effective amounts and in appropriate dosage form ultimately at the discretion of the medical or veterinary practitioner. For example, as known to those skilled in the art, the amount of compounds of the invention required to be pharmaceutically effective will vary with a number of factors such as the mammal's weight, age and general health, the efficacy of the particular compound and formulation, route of administration, nature and extent of the condition being treated, and the effect desired.

The total daily dose may be given as a single dose, multiple doses, or intravenously for a selected period. Efficacy and suitable dosage of a particular compound can be determined by known methods including through use of the protocols of Example 14 which follows. More particularly, for treatment of a tumor in a mammal such as a human, particularly when using more potent compounds of the invention, a suitable effective dose of the compound of the invention according to Formula I through XIX or a subformula thereof will be in the range of 0. 01 to 100 milligrams per kilogram body weight of recipient per day, preferably in the range of 1 to 10 milligrams per kilogram body weight of recipient per day. The desired dose is suitably administered once daily, or as several sub-doses, e. g. 2 to 4 sub-doses administered at appropriate intervals through the day, or other appropriate schedule. Such sub-doses may be administered as unit dosage forms, e. g. , containing from 0.2 to 200 milligrams of compound (s) of the invention per unit dosage, preferably from 2 to 20 milligrams per unit dosage.

The compounds of the present invention may be suitably administered to a subject as a pharmaceutically acceptable salt. Such salts can be prepared in a number of ways. For example, where the compound comprises a basic group such as an amino group, salts can be formed from an organic or inorganic acid, e. g. hydrochloride, sulfate, hemisulfate, phosphate, nitrate, acetate, oxalate, citrate, maleate, etc.

The therapeutic compound (s) may be administered alone, or as part of a pharmaceutical composition, comprising at least one compound of the invention together with one or more acceptable carriers thereof and optionally other therapeutic ingredients, e. g. , other AIDS agents or part of a cocktail of therapeutic agents. The carrier (s) must be"acceptable"in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

The compositions include those suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal or parenteral (including subcutaneous, intramuscular, intravenous and intradermal) administration. The formulations may conveniently be presented in unit dosage form, e. g. , tablets and sustained release capsules, and in liposomes, and may be prepared by any methods well known in the art of pharmacy.

Such methods include the step of bringing into association the to be administered ingredients with the carrier which constitutes one or more accessory ingredients. In general, the compositions are prepared by uniformly and intimately bringing into association the active ingredients with liquid carriers, liposomes or finely divided solid carriers or both, and then if necessary shaping the product.

Compositions of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion, or packed in liposomes and as a bolus, etc.

A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, preservative, surface-active or dispersing agent. Molded tablets may be made by molding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein.

Compositions suitable for topical administration include lozenges comprising the ingredients in a flavored basis, usually sucrose and acacia or tragacanth; pastilles comprising the active ingredient in an inert basis such as gelatin and glycerin, or sucrose and acacia; and mouthwashes comprising the ingredient to be administered in a suitable liquid carrier.

Compositions suitable for topical administration to the skin may be presented as ointments, creams, gets and pastes comprising one or more compounds of the present invention and a pharmaceutically acceptable carrier. A suitable topical delivery system is a transdermal patch containing the ingredient to be administered.

Compositions suitable for rectal administration may be presented as a suppository with a suitable base comprising, for example, cocoa butter or a salicylate.

Compositions suitable for nasal administration wherein the carrier is a solid include a coarse powder having a particle size, for example, in the range 20 to 500 microns which is administered in the manner in which snuff is taken, i. e. , by rapid inhalation through the nasal passage from a container of the powder held close up to the nose. Suitable formulations wherein the carrier is a liquid, for administration, as for example, a nasal spray or as nasal drops, include aqueous or oily solutions of the active ingredient.

Compositions suitable for vaginal administration may be presented as pessaries, tampons, creams, gels, pastes, foams or spray formulations containing in

addition to the active ingredient such carriers as are known in the art to be appropriate.

Compositions suitable for parenteral administration include aqueous and non- aqueous sterile injection solutions which may contain anti-oxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example, sealed ampules and vials, and may be stored in a freeze dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use.

Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.

It should be understood that in addition to the ingredients particularly mentioned above the formulations of this invention may include other agents conventional in the art having regard to the type of formulation in question, for example, those suitable for oral administration may include flavoring agents.

Chemistry As shown in Scheme 1, the well-known Pd-catalyzed Sonogashira reaction between an aryl halide and a terminal alkyne provided convenient access to the analogs of la and lb with a 5'- (co-carboxy-l-alkynyl) side chain or a 5'- (0)- carboxyalkyl) side chain. See, for example, Sonogashira, K; Tohda, Y.; Hagihara, B.

Tetrahedron Lett. 1975,4467-4470 ; and Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara, N. Synthesis 1980,627-630. The key intermediates needed for the coupling reaction were the terminal acetylenic esters 15-17 and the iodide 19, the latter of which was obtained from 2, 4-diamino-5- (2'-methoxybenzyl) pyrimidine (18) by reaction with iodine monochloride as described by Calas and coworkers (Calas, M.; Barbier, A.; Giral, L.; Balmayer, B.; Despaux, E. Eu7 : J. Med. Chem.--Chim.

Ther. 1982, 17, 497-504). The esters were readily prepared from the Cs salts of the commercially available acids 12-14 with benzyl bromide in dry DMF. Without

purification, 15-17 were condensed with 19 in the presence of Et3N and catalytic amounts of (Ph3P) 2PdCl2 and Cul in dry DMF at 60 °C under N2. Because of their limited solubility in nonpolar solvents, the resulting acetylenic esters 20-22 did not lend themselves easily to column chromatography on silica gel, and therefore were converted directly to the acids 2-4 by brief treatment with NaOH in DMSO at room temperature. The yield of 2 and 4 after purification by preparative HPLC on C 1 g silica gel using an isocratic mixture of MeCN and 0.1 MNH40Ac, pH 7.4, as the eluent was 32% and 36%, respectively. In the case of 3, we did not use HPLC but instead attempted to recrystallize the compound from MeOH. This proved to be a bad choice, inasmuch as heating the acetylenic acid in MeOH led to a sharp drop in final purified yield because of extensive degradation to a resinous, base-insoluble product of unknown composition (the crude yield had been comparable to that of 2 and 4).

Scheme 1 Reactants: a, PhCHBr/CsCOs/DMF ; b, ICI/AcOH ; c, (Ph3P) 2PdCIz, Cul, Et3N, DMF; d, NaOH, DMSO ; e, Hz/10% Pd-C, DMF We had originally chosen benzyl esters in Scheme 1 with the intent of using catalytic hydrogenation (H2/Pd-C) to reductively cleave the benzyl group and simultaneously reduce the triple bond to form the saturated acids 5-7, respectively.

However, when hydrogenation was attempted with 21 in DMF solution, the triple bond was reduced but the ester group survived. When reduction was performed in a 1 : 1 mixture of DMF and glacial AcOH with a view to protonating the diaminopyrimidine moiety, which we suspected might be inactivating the Pd-C catalyst enough to prevent debenzylation, reduction occurred ; however the product proved to be totally insoluble in base, and thus could not be a carboxylic acid.

Fortunately, conversion of the acetylenic esters to the desired saturated acids was

achieved satisfactorily by first cleaving the ester group with NaOH and hydrogenating the Na salt in situ in aqueous solution, or in the case of 7 by isolating the free acid and carrying out the reduction in DMF solution. In contrast to 3 (see above), purification of 5 was achieved satisfactorily by recrystallization from MeOH. Preparative HPLC (C1 g silica gel, 20% MeCN in 0.1 MNH40Ac, pH 7.4) was used in the case of 6; however, analytically pure 7 could be obtained by simply dissolving the product of the hydrogenation reaction in dilute NaOH and acidifying the solution with AcOH.

The overall two-step yields of the purified acids 5-7 was 35%, 46%, and 77%, respectively. The 1H NMR spectra of all three compounds were consistent with reduction of the C=C bond, in that there were four additional CH2 hydrogens and a slight upfield shift for the aromatic protons ortho to the w-carboxyalkyl side chain.

Although we had originally planned to prepare compounds 8 and 9 from the Na salt of 2, 4-diamino-5- (2'-methoxy-4'-hydroxybenzyl) pyrimidine, as we had done earlier to obtain la and other 5'-(6)-carboxyalkoxy) analogs from o-bromoalkanoic acids, efforts to apply this method using methyl 4- (bromomethyl) benzoate were thwarted by several side reactions. To circumvent this problem we chose to reverse the synthetic sequence so that formation of the diaminopyrimidine ring would be the last step. Thus, we carried out the synthesis of analogs 8 and 9 according to Scheme 2. Condensation of 3-hydroxy-6-methoxybenzaldehyde (23) with methyl 3- (bromomethyl) -benzoate (24) in the presence of K2CO3 and a catalytic amount of a crown ether, which procedure is described in Rosowsky, A; Forsch, R. A.; Queener, S. F. J. Med. Chem. 2002, 45, 233-241, unexpectedly gave a 79% yield of the previously unknown acetal 25 after recrystallization from MeOH ; however the latter was readily converted to the desired aldehyde 26 by treatment with dilute HCI. The structure of 25 was deduced from its elemental analysis, the absence of absorbance at 1685 cm' in the infrared spectrum, and the presence, in the 1H NMR spectrum, of characteristic signals at 8 3.35 and 8 5.64 for the CH (OMe) 2 group. That O-alkylation had occurred in the expected manner was also evident from the presence of a peak at 8 5.07 corresponding to the OCH2 protons. The overall two-step yield of 26 from 24 was 69%. Interestingly, when 23 was condensed with t-butyl 4- (bromomethyl) benzoate only the expected aldehyde 28 was obtained even though the product was recrystallized from MeOH. The probable reason for this difference in

behavior between the meta and para esters is that dilute citric acid was used during the workup of the reaction of 24 but not 27. Thus it is possible that some residual citric acid was present during the recrystallization from MeOH. The remaining steps were performed according to one of the standard routes TMP analogs, in which the aldehyde is treated sequentially with 3-morpholinopropionitrile, aniline hydrochloride, and guanidine (Kompis, I. ; Wick, A. Helv. Chim. Acta 1977, 60, 3025- 3034; and Roth, B.; Baccanari, D. P.; Sigel, C. W.; Hubbell, J. P.; Eaddy J.; Kao, J.

C.; Grace, M. E.; Grace, M. E.; Rauckman, R. S. J. Med. Chem. 1988, 31, 122-129), and in this case NaOH to cleave the ester groups to acids. Although none of the intermediates in the four-step sequence from 26 and 28 to the final products 8 and 9, respectively, were isolated in pure state before proceeding to the next step, the final acids were purified by preparative HPLC on C 18 silica gel using 18% MeCN in 0.1 M NH40Ac, pH 7.4, as the eluent. Large amounts of nonpolar impurities were easily removed in this manner, and the identity and purity of the products were confirmed established by microchemical and 1H NMR analysis. As expected, 8 and 9 were soluble in dilute aqueous base, and precipitated at a weakly acidic pH.

Scheme 2 Reactants: a, K2CO3, 18-crown-6 ; b, HCI ; c, 3-morpholinoproplonitrile, NaOEt ; d, PhNH2. HCl ; e, H2NC (=NH) NH2 ; f, NaOH The final two compounds in this series of analogs, 10 and 11, were synthesized according to Scheme 3, starting from ethyl salicylate (29) and ethyl 3- hydroxybenzoate (30), respectively. Condensation of the phenols with propargyl bromide in the presence of K2CO3 and a crown ether catalyst in DMF afforded the O-

propargyl ethers 31 and 32. Further reaction of the ethers with iodide 19 in the presence of (Ph3P) 2PdCl2, CuI, and Et3N, followed by saponification, afforded the desired acids in overall two-step yields of 21% and 24%. Neither 31 and 32 nor the ester intermediates 33 and 34 from the Sonogashira reaction were chromatographed, but the final products were carefully purified by preparative HPLC (C18 silica gel, 20% MeCN in 0.1 MNH40Ac, pH 7.4) and characterized by their 1H NMR spectra in DMSO-d6 solution, which displayed the expected resonance signals at 8 3.50 (benzylic CH2), 3.82 (OMe), 5.04 (CH2O), and 7.40 (pyrimidine 6-H) in addition to appropriate peaks for the various protons of the phenyl rings.

Scheme 3 Reactants: a, HC-CCH2Br, K2CO3, 18-crown-6 ; b, (Ph3P) 2PdCI2, Cul, Et3N ; c, NaOH Scheme 4

Reactants: (a) 3-morpholinoprionitrile, NaOMe, DMSO; (b) PhNH2. HCI, EtOH ; (c) H2NC (=NH) NH2, EtOH ; (d) benzyl hexynoate, (Ph3P) 2PdCI2, (Ph3P) 3CuBr, Et2'PrN, DMF; (e) NaOH, DMSO.

Enzyme Inhibition Assays Compounds 2-11 were tested for the ability to inhibit Pc, Tg, and Ma DHFR according to the standardized spectrophotometric assays used in the Queener laboratory, and their potencies and selectivities were compared with updated values for la. lb, TMP, and PTX. See, for example, Broughton, M. C. ; Queener, S. F.

Antimicrob. Agents Chemother. 1991, 35, 1348-1355; and Chio, L.-C. ; Queener, S. F.

Arztinaicrob. Agents Chemother. 1993,37, 1914-1923. The results are presented in Table 1, and discussed for each of enzyme in the following sections.

Table 1. inhibition of P. carinii (Pc), T. gondii (Tg), M. avium (Ma), and rat dihydrofolate reductase by 2,4-diamino-5-(2'-methoxy-5'-<BR> substituted benzyl) pyrimidines. IC50 (µM)a Selectivity Index (Sl)b Cmpd P. carbinii T. gondii M. avium Rat P. carinii T. gondii M. avium 0.25 (0.21- 0.18 (0.15- 0.0048 1a 2.7 (2.502.9) 11 (8.5-13) 16 (12-19) 560 (430-730) 0.30) 0.20) (0.0040-0.0059) 0.054c (0.045- 0.11 (0.066- 0.058c,d 4.6e (3.2- 1b 85 (79-97) 42 (19-72) 79 (19-230) 0.068) 0.17) (0.02-0.16) 6.0) 0.13 0.097 0.0044 4.0 (3.5- 2 31 (24-39) 41 (34-39) 900 (700-1100) (0.12-0.15) (0.093-0.10) (0.0040-0.0049 4.6) 0.028 0.032 0.007 2.2 (1.9- 3 79 (63-100) 69 (52-91) 280 (200-380) (0.025-0.03) (0.027-0.037) (0.0064-0.0095 (2.5 0.87 0.72 0.041 (0.31- 25 (19- 4 28 (19-42) 340 (230-510) 590 (330-1100) (0.77-0.98) (0.064-0.081 0.56) 32) 0.15 0.058 0.35 3.2 (2.5- 5 21 914-31) 54 (39-77) 91 (51-160) (0.13-0.18) (0.052-0.065) (0.025-0.048) 4.0) 0.15 0.0084 0.016 4.1 6 27 (18-41) 490 (340-700) 260 (140-460) (0.13-0.17) (0.075-0.009) (0.011-0.022) (3.1-5.3) 0.53 0.030 0.089 4.6 (4.2- 7 8.6 (6.4-11) 150 (120-190) 52 (38-70) (0.43-0.65) (0.026-0.034) (0.071-0.11) 5.0) 0.89 0.60 (0.53- 0.12 (0.1- 19 (14- 8 21 (13-33) 31 (21-46) 150 (100-230) (0.73-1.1) 0.69) 0.14) 24) 1.2 2.0 (1.7- 0.060 21 (13- 9 17 (9.6-30) 1 (6.4-18) 340 (210-560) (0.098-1.5) 2.2) (0.053-0.069) 29)

Table 1 Continued. 2.3 (2.1- 0.50 (0.44- 0.036 6.2 (5.2- 10 2.7 (2.1-3.5) 13 (9.3-17) 170 (130-230) 2.5) 0.56) (0.032-0.041) 7.4) 5.6e (4.4- 1.6 (1.1- 0.057 14 (11- 11 2.4 (1.6-3.7) 8.3 (4.6-15) 240 (170-250 7.2) 2.4) (0.050-0.065) 16) 0.0010 0.034 0.0024 5000 5000 150 21000 49 (0.00082-0.0012) (0.030-0.039) (0.0021-0.0027) (4300-5800) (3600-7100) (110-190) (2000-2800) 13 (10- 2.8 (2.4- 0.30 (0.26- 180 (160- TMPf 14 (10-20) 65 (48-87) 610 (460-810) 16) 3.3) 0.35) 210) 0.013 0.0043 0.00061 0.0033 PTXf 0.26 (0.17-0.42 0.76 (0.63-0.97 5.4 (4.1-7.2 (0.009-0.017) (0.0040-0.0046) (0.0053-0.0007) (0.0029-0.0039) "Numbers in parentheses are 95% confidence limits. The difference in IC50 between rat liver and each of the parasite enzymes was<BR> determined to be statistically significant at P < 0.01. bSI=IC50 (Pc, Tg, or Ma). Numbers in parenthesis are 95% confidence limits, and<BR> represent a range calculated by dividing the lower end of the 95% confidence interval for rat liver DHFR by the high end of the 95%<BR> confidence interval for Pc, Tg, or Ma DHFR. SI values exceeding 100 are rounded off to two figures. Non-selectivity is denoted by an SI of<BR> <1.0. "Mean of three experiments on different days. "The IC50 of 1b against Ma DHFR was inadvertently recorded as 0.0058 µM in<BR> Rosowsky, A; Forsch, R. A.; Queener, S. F. J. Med. Chem. 2002, 45, 233-241; as result, the SI calculated therein for this compound was off<BR> by a factor of 10. "Mean of two experiments on different days. fTMP = trimethoprim; data taken from Rosowsky, A; Forsch, R. A.;<BR> Queener, S. F. J. Med. Chem. 2002, 45, 233-241. gPTX = piritrexim. Historical IC50 for PTX, obtained with an older sample and cited<BR> previously for 1 were obtained for comparison purposes were the following; Pc DHFR, 0.031 µM; Tg DHFR, 0.017 µM; rat liver, 0.0015<BR> µM. The data in Table 1 were obtained with a newer sample of PTX and the IC50 of PTx against Ma DHFR had not been determined<BR> previously.

Pneumocystis carme DHFR As shown in Table 1, the most potent inhibitor of Pc DHFR among this group was the 5'- (5-carboxy-1-pentynyl) analog 3, with an ICso of 0. 028 gM. Thus, against the enzyme from this organism, 3 was slightly more potent than lb. However, because potency increased by about the same extent against rat DHFR, the selectivity index (SI) as defined in Table 1, footnote b, was not changed significantly. Although there was no substantial improvement in potency or selectivity, this finding was nonetheless of interest because it demonstrated that the oxygen atom at the 5'-position of lb can be safely replaced by a carbon-carbon triple bond where Pc DHFR binding is concerned. It may be noted that the C-C (CH2) 3CO2H side chain in 3 contains the same number of atoms as the O (CH2) 4CO2H side chain in lb, but is less flexible because of the geometric constraints imposed by the triple bond. From the enzyme binding data, it appears that the terminal carboxyl group may nonetheless be adequately positioned in the active site to interact with Arg75 (Pc numbering). Of interest in this regard is that the shorter analog 2 was a slightly weaker inhibitor of both Pc and rat DHFR than 3, a pattern also observed in the previous series of5'- (co- carboxyalkoxy) analogs. See, Rosowsky, A; Forsch, R. A.; Queener, S. F. J. Med.

Chez. 2002, 45, 233-241. However compound 4 displayed a more striking decrease in potency than either 2 or 3 against both the Pc and rat enzymes. Finally, with regard to the potency and selectivity of the alkynes 5-7 versus the alkanes 2-4, a dramatic pattern of structure-activity relationships did not emerge, and we were not able to determine whether a carboxyalkyne or carboxyalkane side chain was superior. With respect to compounds 8-11 as inhibitors of Pc versus rat DHFR, it can be seen from Table 1 that they are all considerably weaker than lb or 3 against the Pc enzyme, and that the potency difference is greater against this enzyme than against the rat enzyme, resulting in an overall decrease in selectivity. At least with these examples, therefore, it appears that the introduction of a bulky second phenyl ring in the side chain, together with replacement of the aliphatic COOH group by an aromatic one, was unfavorable. It may be noted that, when the total number of side-chain atoms is added up, the number of atoms separating the carboxyl group from the 2'- methoxyphenyl ring is five in 8, six in 9 and 10, and seven in 11. The corresponding

number of atoms is four in 2 and 5, five in 3 and 6, and six in 4 and 7. Thus, among the analogs with an extra phenyl ring, 8-10 most closely approximate lb and 2-7 in terms of the total number of atoms (aromatic and aliphatic) separating the carboxyl group from the rest of the molecule, whereas in 11 there is one additional atom.

Toxoplasma gondii DHFR In contrast to Pc DHFR, the most potent inhibitor of the Tg enzyme was 6, with an ICso of 0. 0084, uM (Table 1). Whereas this corresponded to a roughly one- log increase in binding relative to lb, a comparable effect was not observed with rat DHFR. As a result, the selectivity index (SI) of 6 was 490 as compared with a value of only 42 in the case of lb. Thus, replacement of the oxygen atom at the 5'-position of lb by a saturated carbon resulted in a considerable improvement in both potency and selectivity. Interestingly, this was in contrast to the decreased potency and selectivity of 6 relative to lb against Pc DHFR and of 6 relative to la against Ma DHFR.

The published literature on Tg DHFR inhibitors contains a large number of mono-, di-, and tricyclic 2,4-diaminopyrimidines that are much more potent than TMP, but only a handful that are both more potent and more selective against Tg DHFR versus rat DHFR under our standardized assay conditions. As summarized in Table 2, these compounds include 35 (Rosowsky, A; Forsch, R. A.; Queener, S. F. J.

Med. Chem. 2002, 45, 233-241), a two-carbon homolog of 1, the TMP analog 36 (epiroprim) (Gangjee, A.; Vasudevan, A.; Queener, S. F.; Kisliuk, R. L. J. Med.

Chez. 1996, 39, 1438-1446), the 2,4-diamino-5-aryl-6-ethylpyrimidines 37 and 38 (Stevens, M. F. G.; Phillip, K. S.; Rathbone, D. L.; O'Shea, D. M.; Queener, S. F.; Schwalbe, C. H.; Lambert, P. A. JMed. Chem. 1997, 40, 1886-1893), the 2,4- diamino-6-substituted pteridines 39 (Piper, J. R.; Johnson, C. A.; Krauth, C. A.; Carter, R. L.; Hosmer, C. A.; Queener, S. F.; Borotz, S. E.; Pfefferkorn, E. R. JMed Chem. 1996, 39, 1271-1280. ) and 40 (Rosowsky, A.; Cody, G.; Galitsky, N.; Fu, H.; Papoulis, A. T.; Queener, S. F. J. Med. Chem. 1999, 42, 4853-4860. ), the 2,4- diamino-6-benzylaminopyrido [2, 3-d] pyrimidine 41 (albeit only when tested against Tg versus human instead of rat DHF, and under assay conditions different from those

typically used with the other compounds reported; see, Gangjee, A.; Vasudevan, A.; Queener, S. F. ; Kisliuk, R. L. J. Med. Chem. 1996, 39, 1438-1446), and the 2,4- diamino-5-substituted pyrrolo [2, 3-d] pyrimidines 42 and 43 (Gangjee, A.; Mavandadi, F. ; Queener, S. F. ; McGuire, J. J. J. Med. Chem. 1995, 38, 2158-2165). Very surprisingly, three 2,4-diamino-6, 7-disubstituted pteridines (44-46) have also been reported to be among this select group (Chio, L. -C. ; Queener, S. F. Antimicrob.

Agents Chemother. 1993, 37, 1914-1923). Bulky substitution at the 7-position of 2,4- diaminopteridines is generally considered very unfavorable for DHFR binding.

However it is possible that, in the case of the Tg enzyme, the selectivity of these compounds relative to rat DHFR reflects the fact that the Tg enzyme is a larger difunctional protein containing both a thymidylate synthase (TS) and DHFR domain (Roos, D. S. J. Biol. Chem. 1993, 268, 6269-6280). This question will presumably remain unanswered until the 3D structure of the Tg enzyme is fully solved. On the basis of its 330-fold increase in potency and 7. 5-fold increase in selectivity relative to TMP against Tg DHFR, and in light of its very good profile when compared to the inhibitors shown in Table 2, compound 6 may be viewed as a most interesting lead for further structure-activity optimization.

Table 2. Various compounds of the invention and the literature possessing inhibitory activity against Tg DHFR. NHZ H2 / \ . Rz HZN 6 : R=2'-OMe-5'- 37 : RIR2= 35 : R 38 : R'=R 36 : R = 3', 5t (OMe) 47 pM, SI = 160) Me nez N N NH2 H2 39 : R=CHZSCHS 9 40 : R 043 pM, 41 (IC, o 028 pM, Sl H 2 H2NXNX HZN 42 : R=2', 44 : R'=R=C6H5 43 : R= 46 : R'= = 86 pM, SI =

I \ R/Mycobacterium avium DHFR As indicated in Table 1, compound 2 was a much better inhibitor of Ma DHFR than TMP, and was similar to the previously reported 5'-O- (5-carboxybutyloxy) analog la. Indeed, with its nearly 3-log selectivity for Ma DHFR relative to the rat enzyme and its approximately 70-fold superiority over TMP in terms of potency, 2 ranks among the best inhibitors of Ma DHFR described to date. Although it stands out among the other compounds tested, there were also several analogues with respectable SI values in the 200-600 range. However, it should be noted that high SI value were not always accompanied by high potency. Thus, while the calculated SI of 590 listed for compound 4 had a range (330-1100) that overlapped that of 2 (700- 1100), its potency against both Ma and rat DHFR was considerably lower.

Suling and coworkers recently published data on a library of almost eighty 2,4-diaminopyrido [2, 3-dgpyrimidines with either arylamino or arylthiomethyl groups at the 6-position as inhibitors of Ma versus human DHFR. See, Suling, W. J.; Seitz, L.

E.; Pathak, V.; Westbrook, L.; Barrow, E. W.; Zywno-Van Ginkel, S.; Reynolds, R.

C.; Piper, J. R.; Barrow, W. W. A72timicrob. 4genets Chemotl7er. 2000, 44, 2784-2793.

The most potent member of their series against Ma DHFR was 2, 4-diamino-6- (2'- methyl-4'-chloroanilino) methyl-5-methylpyrido [2, 3-dJpyrimidine (47), with an IC50 of 0.00019 pM. However, because 47 was also a potent inhibitor of a mammalian DHFR (human in this case), its SI value was only 15. A second compound, 2,4- diamino-6- (2', 5'-diethoxy-anilino) methyl-5-methylpyrido [2, 3-dlpyrimidine (48), on the other hand, had ICso values of 0. 00084 and 2. 3, uM against Ma and human DHFR, respectively. Unfortunately an ICso value for 48 against rat DHFR was not reported, and the assay conditions differed in some respects from those used routinely by the Queener laboratory. The binding of inhibitors to DHFR can vary substantially depending on the pH, the temperature, and other variables. Thus, it remains to be determined how 2 and 48 would compare if they were tested under identical assay conditions in the same laboratory. Irrespective of the outcome of such a comparison, the excellent combination of potency reported here over a range of 2, 4-diamino-5- (substituted benzyl) pyrimidines, including some that are not particularly potent or selective against Pc or Tg DHFR, demonstrates that potency and selectivity against Ma DHFR does not require the inhibitor to be a fused-ring 2,4-diamino-pyrimidine.

47: R = 2'-Me-4'-Cl 48: R= 2', 5'-(OEt) 2 The 3D structure of the ternary complex of Ma DHFR with NADPH and TMP has not been reported. However it is noteworthy that, in a recent study of the closely related enzyme from M. tuberculosis by X-ray crystallography, Li and coworkers suggested that TMP analogs with extended hydrophobic substitution on the benzyl ring might be designed to selectively fit into a binding pocket that appears to not be available in the active site of mammalian DHFR enzymes. See, Li, R; Sirawaporn, R.; Chitnumsub, P.; Sirawaporn, W.; Wooden, J.; Athappilly, F. ; Turley, S.; Hol, W.

G. J. Mol. Biol. 1999, 295, 307-323. Although they are 2', 5- rather than 3', 4', 5- trisubstituted benzyl derivatives, it would be of interest to determine whether 2-4 can bind to the Ma enzyme in such a way as to allow the hydrocarbon portion of the 5'- (co-carboxy-1-alkynyl) side chain to make van der Waals contact with this hydrophobic domain.

A variety of small-molecule antifolates of the 2, 4-diamino-5- (substituted benzyl) -pyrimidine family, each more potent and/or more selective than TMP against at least one of three different opportunistic pathogens of AIDS, have been discovered in the development of the present invention. For example, 2, 4-diamino-5- [5'- (4- carboxy-l-pentynyl)-2'-methoxybenzyl] pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 relative to the rat liver enzyme, and was 430 times more potent than TMP. Another compound of the invention, 5- [5'- (5-carboxy-l-butynyl)-2'- methoxybenzyl] pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP.

The third compound, 2, 4-diamino-5- [5'- (5-carboxypentyl)-2'-methoxy- benzyl] pyrimidine (6) had a selectivity index of 490 against Tg DHFR, and was 320 times more potent than TMP. A fourth compound of the invention, 2, 4-diamino-5- [5'-

(6-carboxy-1-hexynyl)-2'-methoxy-benzyl] pyrimidine (4), provides a selectivity index of >300 against both Tg and Ma DHFR notwithstanding the lower potency of compound 4 against all three of the parasite enzymes (Pc, Tg, and Ma) when compared to the level of inhibition for compounds 3 and 6.

The following non-limiting examples are illustrative of the invention. All documents mentioned herein are incorporated herein by reference in their entirety.

GENERAL EXPERIMENTAL COMMENTS IR spectra were obtained on a Perkin-Elmer Model 781 double-beam recording spectrophoto-meter. Only peaks with wave numbers above 1200 cm'1 are reported. 1H NMR spectra were recorded in DMSO-d6 solution at 200 MHz on a Varian VX200 instrument. Each peak is denoted as a singlet (s), broad singlet (br s), doublet (d), doublet of doublets (dd), triplet (t), doublet of triplets (dt), or pentet (p).

Integrated peak areas are not listed when the resonance signal was partly obscured by water or DMSO, or in the case of NH2 groups on the pyrimidine ring. Signals for the aromatic protons in compounds with two phenyl rings are identified according to the numbering in Schemes 2 and 3. TLC analyses were on Whatman MK6F silica gel plates with UV illumination at 254 nm. Column chromatography was on Baker 7024 flash silica gel (40 go particle size). HPLC separations were performed on Cl8 radial compression cartridges (Millipore, Milord, MA; analytical, 5 urn particle size, 5 x 100 mm; preparative, 15, um particle size, 25 x 100 mm). Melting points were measured in Pyrex capillary tubes in a Mel-Temp apparatus (Fisher, Pittsburgh, PA), and are not corrected. 3-Morpholinopropionitrile was prepared by adding acrylonitrile dropwise to an equimolar amount of morpholine in an ice-bath, and stirring the mixture at room temperature for 1 h. The resulting light-yellow oil did not require purification and was used directly. 2, 4-Diamino-5- (2'-methoxybenzyl) pyrimidine (18) and 2, 4-diamino-5- (5'-iodo-2'-methoxybenzyl) pyrimidine (19) were prepared according to the literature: 18,42% yield, mp 160-161°C (lit. 160 OC) ; 19,66% yield, mp 207-208 °C, lit. 205°C). Other chemicals were purchased from Sigma-Aldrich (St.

Louis, MO), Acros Organics (Pittsburgh, PA), or Lancaster Synthesis (Windham, NH). Elemental analyses were performed by Quantitative Technologies, Inc.

(Whitehouse, NJ), and were within t 0.4% of theoretical values. Where

microanalytical results were consistent with residual acetic acid, its presence in the sample was confirmed by the finding of a methyl signal at 8 1.9 in the 1H NMR spectrum.

EXAMPLES: EXAMPLE 1: 2, 4-Diamino-5- [5'- (4-carboxy-l-butynyl)-2'-methoxy) benzyl] pyrimidine (2).

Step 1. Benzyl 4-pentynoate (15) was prepared by stirring a solution of 4- pentynoic acid (12) (1.96 g, 0.02 mol) in dry DMF (25 mL) with Cs2CO3 (3.25 g, 0.01 mol) for 10 min, followed by addition of benzyl bromide (2.38 mL, 3.42 g, 0.02 mol). After 18 h of stirring at room temperature, the solvent was removed by rotary evaporation (vacuum pump) and the residue was partitioned between EtOAc and H20. Evaporation of the organic layer gave 15 as an oil whose NMR spectrum showed that it still contained some DMF and a trace of benzyl bromide but was suitable for use in the next step.

Step 2. A stirred mixture of 15 (1.3 g, estimated by NMR to contain ca. 6.0 mmol), iodide 19 (1.42 g, 4.0 mmol), (Ph3P) 2PdC12 (15 mg), Cul (1 mg), and Et3N (5 mL) in dry DMF (5 mL) was heated at 60 OC for 20 h. A clear solution formed after ca. 1 h. The solvent was removed by rotary evaporation, and the residue was triturated successively with isooctane and H20. Recrystallization from EtOH afforded 20 as a light-yellow powder (1.59 g, mp 208 oc) which was used in the next step without additional purification.

Step 3. A solution of 20 (416 mg, 1.0 mmol) in dry DMSO (4 mL) was treated dropwise with 1 NNaOH with swirling. The mixture was diluted immediately with H20 (40 mL), acidified with 10% AcOH, and chilled in ice. The precipitate was collected and dried to obtain a beige solid; crude yield 239 mg. Analytically pure 2 for bioassay was obtained by preparative HPLC (Clg silica gel, 13% MeCN in 0.1 M NH40Ac, pH 7.4). Appropriately pooled fractions were concentrated and freeze-

dried; yield 123 mg (32% based on the amount of 19 used); mp 162-163 oc (softening without giving a true melt); IR (KBr) v 3500-2800 (broad), 3350,3210, 2930,1665, 1560-1530,1505, 1460,1405, 1295,1115 cm-1 ; 1H NMR (DMSO-d6) 8 2.50 (m, 4H, CH2CH2, partly overlapped by DMSO peak), 3.49 (s, 2H, bridge CH2), 3.87 (s, 3H, OMe), 5.84 (br s, NH2), 6.16 (br s, NH2), 7.00 (m, 2H, aryl 3'-and 6'-H), 7.22 (d, J= 9 Hz, 1H, aryl 4'-H), 7.39 (s, 1H, pyrimidine 6-H). Anal.

(ClgH2oN403-0. 5CH3CO2H-0. 2HZO) Calc. C 61.02, H 6.04, N 14.98 ; Found C 60.93, H 5.93, N 14. 98.

EXAMPLE 2: 2, 4-Diamino-5- [5'- (4-carboxy-1-pentynyl)-2'-methoxy) benzyl] pyrimidine (3).

Step 1. Benzyl 5-hexynoate (16) was prepared by stirring a solution of 5- hexynoic acid (13) (1.12 g, 0.01 mol) in dry DMF (25 mL) with Cs2CO3 (1.63 g, 0.005 mol) for 10 min, followed by addition of benzyl bromide (1.19 mL, 1.71 g, 0.01 mol). After 18 h of stirring at room temperature, the solvent was removed by rotary evaporation (vacuum pump) and the residue was partitioned between EtOAc and H20. Evaporation of the organic layer gave 16 as an oil suitable for use directly in the next step.

Step 2. A stirred mixture of 16 (0.65 g, estimated by NMR to contain ca. 36.0 mmol), iodide 19 (1.42 g, 4.0 mmol), (Ph3P) 2PdCl2 (10 mg), Cul (1 mg), and Et3N (3 mL) in dry DMF (3 mL) was heated at 60 OC for 72 h. The solvent was removed by rotary evaporation, and the residue was triturated successively with isooctane and H20. Attempted recrystallization from EtOH gave only a gum. Therefore the solvent was evaporated, and the residue was re-dissolved in hot THF (40 mL). A small amount of insoluble material was filtered off, the filtrate was concentrated to dryness, and the residue, containing ester 21, was taken up directly in dry DMSO (6 mL). The solution was treated dropwise with 1 NNaOH (6 mL), then diluted with H20 (100 mL) and chilled. A small amount of residual non-saponifiable material was removed by filtration, and the filtrate was acidified with 10% AcOH. The precipitate was collected and dried in a lyophilization apparatus to obtain a beige solid. Attempted

recrystallization from hot MeOH led to separation of a brown insoluble gum suggesting that decomposition was occurring. The methanolic solution was immediately decanted and left to cool passively in the hood at room temperature, producing a first crop of analytically pure 3 as white crystals weighing 32 mg (5%); mp 121-124 OC (softening without giving a true melt); IR (KBr) v 3500-2800 (broad), 3350,3210, 2930,1665, 1560-1530,1505, 1460,1405, 1295,1115 cm~1 ; 1HNMR (DMSO-d6) 8 1.72 (p, J= 7 Hz, 2H, C-CCH2CH2CH2), 2. 37 (two overlapping t, 4H, C=-CCH2CH2CH2), 3.50 (s, 2H, bridge CH2), 3.80 (s, 3H, OMe partly overlapped by H20), 5.86 (br s, NH2), 6.20 (br s, NH2), 6. 95 (m, 2H, aryl 3'-and 6'-H), 7.24 (dd, J = 8 Hz, J= 2 Hz, 1H, aryl 4'-H), 7.39 (s, 1H, pyrimidine 6-H). Another 153 mg (24%) of less pure 3 was obtained from the mother liquor and used for hydrogenation as described below. Anal. (ClgH2oN403-0. 5AcOH-0. 2 H20) Calc. C 54.51, H 6.26, N 14.61 ; Found C 54.67, H 6.01, N 14.65.

EXAMPLE 3: 2, 4-Diamino-5- [5'- (6-carboxy-l-hexynyl)-2'-methoxy) benzyl] pyrimidine (4).

Step 1. Benzyl 6-heptynoate (17) was prepared by stirring a solution of 6- heptynoic acid (14) (1.26 g, 0.01 mol) in dry DMF (15 mL) with Cs2CO3 (1.63 g, 0.005 mol) for 10 min, followed by addition of benzyl bromide (1.19 mL, 1.71 g, 0. 01 mol). After 18 h of stirring at room temperature, the solvent was removed by rotary evaporation (vacuum pump) and the residue was partitioned between EtOAc and H20. Evaporation of the organic layer gave 17 as an oil suitable for use directly in the next step.

Step 2. A stirred mixture of 17 (0.65 g, estimated by NMR to contain ca. 3.0 mmol), iodide 19 (0.71 g, 2.0 mmol), (Ph3P) 2PdC12 (20 mg), Cul (2 mg), and Et3N (5 mL) in dry DMF (5 mL) was heated at 65 OC for 2.5 h. Additional amounts of (Ph3P) 2PdCl2 (10 mg), Cul (1 mg) were added, and heating was continued for 18 h.

The solvent was evaporated under reduced pressure, and the residue was triturated successively with isooctane and H20. The solid was taken up in DMSO (5 mL) and treated with a solution ofNaOH (220 mg, 4.4 mmol) in H20 (1 mL). The solution

was diluted to 80 mL with H2O, then chilled, adjusted to ca. pH 8 with 10% AcOH, and filtered to remove a trace of insoluble material. The filtrate was subjected to preparative HPLC (Clg silica gel, 20% MeCN in 0.1 M NH4OAc, pH 7.4, 10 mL/min) and fractions eluting in the major peak (ca. 12 min on the analytical column at 1.0 mL/min) were pooled and freeze-dried to obtain 4 as a white solid; 292 mg (36%); mp 187-189 oc (softening without giving a true melt); IR (KBr) v 3370,3220, 2950,2880, 2850br, 1690sh, 1670,1565, 1540,1505, 1465,1450sh, 1430,1405, 1375s, 1340,1320, 1295,1350, 1300 cm-1 ; 1H NMR (DMSO-d6) 6 1.63 (m, 4H, CH2CH2CH2CO2H), 2.18 (t, J= 7 Hz, 2H, CH2CO2H), 2.39 (t, J= 7 Hz, C-CCH2, 3.80 (s, OMe, partly overlapped by broad H20 peak), 5.74 (br s, NH2), 6.09 (br s, NH2), 6.93 (d, J= 8 Hz, 1H, 3'-H), 7.02 (d, J = 2 Hz, 1H, 6'-H), 7.22 (dd, J = 8 Hz, J = 2 Hz, 1H, 4'-H), 7.41 (s, 1H, pyrimidine 6-H). The signal for the CH2 bridge was completely obscured by a strong H20 peak. Anal. (ClgH22N403 2. 75H2O) Calc. C 56.49, H 6.86, N 13.87 ; Found C 56.71, H 6.61, N 13.66.

EXAMPLE 4: 2, 4-Diamino-5- [5'- (4-carboxybutyl)-2'-methoxy) benzyl] pyrimidine (5).

A solution of recrystallized 20 (416 mg, 1. 0 mmol) in dry DMF (20 mL) containing 10% % Pd-C (100 mg) was shaken under H2 (50 psi initial pressure) for 18 h. After filtration to remove the catalyst, the solution was evaporated to a solid which was not soluble in NaOH, indicating that the ester group had survived. The solid, assumed to be the benzyl ester of 5, was dissolved directly in hot EtOH (20 mL) and treated with 1 NNaOH (2 mL). The solvent was evaporated under reduced pressure, and the residue was taken up in H2O. A trace of cloudiness, indicating that a trace of ester was still present, was discharged by adding another small portion of 1 NNaOH and some EtOH. The volume was reduced by rotary evaporation, and 10% AcOH was added dropwise until a solid formed, which was filtered, and dried on a lyophilizer to obtain 5 as a white powder (117 mg, 35%); mp 134-137 C (softening without giving a true melt) ; IR (KBr) v 3330, 3180,2930, 2850,1660, 1560,1505, 1455,1400, 1290, 1250 cm-1 ; 1H NMR (DMSO-d6) 8 1.46 (m, 4H, CH2CH2CH2CO2H), 1.77 (m, 4H,

CH2CH2CH2CH2C02H), 3.7 (s, 2H, bridge CH2), 3.75 (s, OMe, partly overlapped by broad H2O peak), 5.66 (br s, NH2), 6.03 (br s, NH2), 6. 89 (m, 3H, 3'-, 4'-, and 6'- H), 7. 34 (s, 1H, pyrimidine 6-H). Anal (C17H22N403-0. 5 AcOH) Calc. C 59.99, H 6. 71, N 15. 55 ; Found C 60.14, H 6. 61, N 15. 35.

EXAMPLE 5: 2, 4-Diamino-5- [5'- (5-carboxypentyl)-2'-methoxy) benzyl] pyrimidine (6).

Benzyl 5-hexynoate (16) (0.65 g of non-purified ester, ca. 3.0 mmol, prepared from 11 as described above) was heated with iodide 19 (0.71 g, 2.0 mmol), (Ph3P) 2PdCl2 (10 mg), CuI (1 mg), and Et3N (3 mL) in dry DMF (3 mL) under N2 at 60 °C for 3.5 h. Solution occurred after ca. 1 h. The solvent was evaporated under reduced pressure, the residue was taken up in warm 95% EtOH (60 mL), and the solution, containing ester 21, was treated with 1 MNaOH (6 mL). The EtOH was evaporated, and replaced with H2O (50 mL). The mixture was chilled and filtered, and the filtrate was transferred directly to a Parr apparatus and subjected to catalytic hydrogenation (42 psi initial pressure) in presence of 10% Pd-C (85 mg). The catalyst was filtered off, and the filtrate was acidified with 10% AcOH. The precipitated solid was collected and dried on a lyophilizer; yield ca. 0.4 g. Analytical HPLC (C 1 g silica gel, 20% MeCN in 0.1 MNH4OAc, pH 7.4, 1 mL/min) showed a major peak eluting at 12 min, along with several unidentified impurities. Preparative HPLC using the same eluent system, pooling of appropriate fractions,, and freeze-drying, afforded 6 as a white powder (334 mg, 46%); mp 96-98 OC (softening without giving a true melt); IR (KBr) v 3350,3200, 2930,2860, 1660,1560, 1505,1460, 1405,1290, 1250 cm-1 ; 1H NMR (DMSO-d6) 8 1.26 (m, 2H, CH2CH2CH2CO2H), 1.45 (p, J= 7 Hz, 4H, CH2CH2CH2CH2CO2H), 2.13 (t, J= 7 Hz, 2H, benzylic CH2), 2.45 (t, CH2C02H, partly overlapped by DMSO peak), 3. 48 (s, bridge CH2, partly overlapped by broad H20 peak), 3.76 (s, OMe, partly overlapped by broad H20 peak), 5.66 (br s, NH2), 6.04 (br s, NH2), 6.90 (m, 2H, aryl 3'-and 6'-H), 7.00 (dd, J= 8 Hz, J= 2 Hz, 1H, aryl 4'-H), 7. 35 (s, 1H, pyrimidine 6-H). Anal. (ClgH24N402-1. 25H20) Calc. C 58. 92, H 7. 28, N 15.27 ; Found C 59.07, H 7.17, N 15.40.

EXAMPLE 6: 2, 4-Diamino-5- [5'- (6-carboxyhexyl)-2'-methoxy) benzyl] pyrimidine (7).

A solution of 4 (120 mg, 0.3 mmol) in DMF (10 mL) was shaken under H2 (initial pressure 3 atm) in the presence of 5% Pd-C in a Parr apparatus for 20 h. The catalyst was removed, and the solvent evaporated under reduced pressure. The residue, consisting of the benzyl ester of 7, was treated with a small volume of dilute NaOH, and a trace of insoluble material was filtered off. The filtrate was acidified with 10% AcOH and chilled, and the precipitate was collected and dried on a lyophilizer to obtain 7 as a white solid; 115 mg (77%); mp 101-105 °C (softening without giving a true melt); IR (KBr) v 2860,3210, 2950,2870, 1670,1565, 1510, 1470,1410, 1295,1260 cm-1 ; 1H NMR (DMSO-d6) 6 1.23 (poorly resolved m, 4H, CH2CH2CH2CH2CO2H), 1.45 (m, 4H, CH2CH2CH2CH2CH2CO2H), 2.14 (t, J = 7 Hz, 2H, CH2C02H), 2.43 (t, J = 7 Hz, benzylic CH2, partly overlapped by DMSO), 3.74 (s, OMe, partly overlapped by broad H20 peak), 5.65 (br s, NH2), 6.03 (br s, NH2), 6.88 (m, 2H, 3'-and 6'-H), 6. 98 (d, J = 8 Hz, 1H, 4'-H), 7.32 (s, 1H, pyrimidine 6-H). The signal for the CH2 bridge was obscured by a strong H20 peak. Anal.

(ClgH26N403 AcOH 1. 3H2O) Calc. C 57.08, H 7.44, N 12. 68 ; Found C 57.22, H 7.16, N 12. 87.

EXAMPLE 7: Methyl 3- (3-Formyl-4-methoxyphenozymethyl) benzoate (26).

Step 1. A stirred mixture of 3-hydroxy-6-methoxybenzaldehyde (23) (456 mg, 3.0 mmol), methyl 3-bromomethylbenzoate (24) (687 mg, 3.0 mmol), K2C03 (1.04 g, 7.5 mmol), and 18-crown-6 (79 mg, 0.3 mmol) in dry DMF (10 mL) was heated at 70 °C for 20 hr. The mixture was cooled to room temperature, the salts were filtered off, and the solvent was removed by rotary evaporation using a vacuum pump. The residue was partitioned between EtOAc and dilute aqueous citric acid. Evaporation of the organic layer gave a tan solid (1.03 g), which on recrystallization from MeOH proved unexpectedly to be the dimethyl acetal 25 ; yield 816 mg (79%); mp 65-66 C ; IR (KBr) v 3010, 2970,2920, 2850,1730, 1690w, 1615,1595, 1505,1470, 1455,

1440,1405, 1380,1370, 1290,1235, 1210 cm-1 ; 1H NMR (CDC13) 6 3. 35 (s, 6H, two OMe groups of acetal), 3.81 (s, 3H, ether OMe), 3.93 (s, 3H, ester OMe), 5.07 (s, 2H, benzylic CH2), 5.64 (s, 1H, acetal CH), 6.82 (d, J= 9H, 1H, aryl 5-H), 6.91 (dd, J = 9 Hz, J = 3 Hz, 1H, aryl 6-H), 7.21 (d, J= 3 Hz, 1H, aryl 4-H), 7.45 (t, J = 8 Hz, 1H, aryl 5'-H), 7.64 (d, J= 7 Hz, 1H, aryl 6'-H), 7.99 (d, J= 7 Hz, 1H, aryl 4'-H), 8.11 (s, 1H, aryl 2'-H). Anal. (C1gH2206) Calc. C 65.88, H 6.40 ; Found C 65.89, H 6.11.

Step 2. The acetal 25 from the preceding step was dissolved in THF (10 mL), and the solution was cooled in an ice bath and stirred while cold 1 N ICI (10 mL) was added dropwise, After 25 min at 0 OC, the mixture was diluted with isooctane. Partial precipitation occurred, but when TLC showed that both the solid and the solution contained an identical single spot (Rf0. 5, silica gel, 1: 1 EtOAc-isooctane) they were re-combined in EtOAc, and the solution washed with 5% NaHCO3. Evaporation of the organic layer afforded a solid (0.7 g crude yield), which on recrystallization from MeOH with 3 drops of added Et3N afforded aldehyde 26 as off-white flakes (617 mg, 69%); mp 102-103 C ; IR (KBr) v 2960w, 2880w, 1730,1685, 1615,1640w, 1500, 1475,1455, 1430,1405, 1385,1320, 1295,1280, 1265,1225, 1210 cm-1 ; IH NMR (CDC13) 8 3.91 (s, 3H, ether OMe), 3.93 (s, 3H, ester OMe), 5.09 (s, 2H, CH2O), 6.96 (d, J= 9 Hz, 1H aryl 5-H), 7.21 (dd, J= 9 Hz, J= 3 Hz, 1H, aryl 6-H), 7.43 (d, J = 3 Hz, 1H, aryl 4-H), 7.48 (d, J= 7 Hz, 1H, aryl 6'-H), 7.63 (d, J= 8 Hz, 1H, aryl 5'- H), 8. 01 (d, J= 8 Hz, 1H, aryl 4'-H), 8.11 (s, 1H, aryl 2'-H), 10.45 (s, 1H, CH=O).

Anal. (C17Hl6Os-0. 1H2O) Calc. C 67.59, H 5.40 ; Found C 67.42, H 5.22.

EXAMPLE 8: 2, 4-Diamino-5- [2'-methoxy-5'- (3"-carboxybenzyloxy) benzyl] pyrimidine (8).

Step 1. Metallic Na (23 mg, 1.0 mmol) was dissolved in absolute EtOH (30 mL), and the solvent was removed by rotary evaporation and the residue re-dissolved in dry DMSO (2 mL). 3-Morpholinopropionitrile (280 mg, 2.0 mmol) was added, the reaction mixture was placed in an oil bath pre-heated to 100 OC. A solution of 26 (600 mg, 2.0 mmol) in DMSO (3 mL, with slight warming as needed) was added all at once, and heating was continued for 20 min. A second portion of NaOMe (1.0 mmol

in DMSO) was added, and heating was resumed for another 20 min. The reaction mixture was cooled and partitioned between EtOAc and dilute aqueous citric acid.

The EtOAc layer was evaporated and the residue was dissolved in absolute EtOH (20 mL), aniline hydrochloride (389 mg, 3.0 mmol) was added, and the mixture was heated under reflux for 30 min and set aside until the next step.

Step 2. Metallic Na (184 mg, 8.0 mmol) was dissolved in absolute EtOH (25 mL), and guanidine hydrochloride (382 mg, 4.0 mmol) was added. The resulting mixture, containing some precipitated NaCl, was combined with the ethanolic solution from the preceding step. The reaction mixture was heated under reflux for 18 h, then chilled and filtered. The filter cake was taken up in H20, and the pH neutralized with 10% AcOH. A trace of solid precipitate, and was collected and redissolved in a small volume of 1 NNaOH. This solution was added back to the filtrate, which was then basified with 1 NNaOH (5 mL) and concentrated to dryness by rotary evaporation. The residue was taken up in H2O (40 mL), the solution acidified with 10% AcOH and chilled, and the precipitate was collected, dried on a lyophilizer, and purified for elemental analysis and bioassay by preparative HPLC (Clg silica gel, 18% MeCN in 0.1 MNH40Ac, pH 7.4). Appropriately pooled fractions were freeze-dried, the solid was re-dissolved in 1 NNaOH. A trace of solid was filtered off, the filtrate was re-acidified with 10% AcOH and chilled, and the precipitate was collected and dried in a lyophilizer to obtain 8 as a white solid (66 mg, 9% overall yield from 26); mp ca. 140 C (softening without giving a true melt); IR (KBr) v 3325-3380, 2920w, 1655,1535br, 1495, 1380, 1275 cm-1; 1H NMR (DMSO- d6) 8 3.50 (s, bridge benzylic CH2, partially overlapped by broad H20 peak), 3.74 (s, OMe, partially overlapped by broad H20 peak), 5.06 (s, 2H, CH20), 6.18 (br s, NH2), 6.37 (br s, NH2), 6.83 (m, 3H, aryl 3'-, 4'-, and 6'-H), 7.32 (s, 1H pyrimidine 6- H), 7.47 (t, J= 8 Hz, 1H, aryl 5"-H), 7.61 (d, J= 7 Hz, aryl 4"-H), 7. 87 (d, J= 7 Hz, 1H, aryl 6"-H), 7.99 (s, 1H, aryl 2"-H). Anal. (C20H20N404-0. 1 AcOH-2H2O) Calc.

C 57.43, H 5.82, N 13.26 ; Found C 57.79, H 5.44, N 12.93.

EXAMPLE 9: ter-butyl 4- (3-formyl-4-methoxyphenoxymethyl) benzoate (28).

To a 4: 1 THF-DMF mixture (10 mL) were sequentially added tert-butyl 4- bromomethylbenzoate (27) (1.08 g, 4.0 mmol), 3-hydroxy-6-methoxybenzaldehyde (23) (496 mg, 3.25 mmol), 2 K2C03 (1. 38 g, 4.0 mmol), and 18-crown-6 (106 mg, 0.4 mmol). The mixture was heated at 70 °C for 40 min, after which the THF was blown off with a stream of air. TLC (silica gel, 1: 1 EtOAc-isooctane) showed some unchanged bromide (Rf 0. 6) and phenol (Rf 0. 3), along with a small new spot at Rf 0.5 (blue-fluorescent) corresponding to the desired product. Replacement of the THF and heating for another 66 h led to complete disappearance of the phenol (Rf0. 3). The reaction mixture was diluted with EtOAc, and the combined organic solvents were decanted from the salts, washed with H20, and evaporated to dryness under reduced pressure to obtain a solid (1.3 g). Recrystallization from MeOH afforded 28 as a light- yellow powder (0.85 g, 76%); mp 91-92 C ; IR (KBr) v 3000,2980, 1860,1700, 1675,1615, 1585, 1575,1495, 1470,1455, 1435,1425, 1410,1395, 1365,1315, 1300,1280, 1255,1220, 1200 cm-1 ; 1HNMR (CDC13) 6 1.60 (s, 9H, t-Bu), 3.90 (s, 3H, OMe), 5.11 (s, 2H benzylic CH2), 6.94 (d, J= 9 Hz, 1H, 5-H), 7.21 (dd, J= 9 Hz, J= 3 Hz, 6-H), 7.41 (d, J= 3 Hz, 1H, 4-H), 7.46 (d, J= 8 Hz, 2H, 2'-and 6'-H), 8.00 (d, J= 8 Hz, 2H, 3'-and 5'-H). Anal. (C20H22os) Calc. C 70.16, H 6. 48 ; Found C 69. 86 ; H 6.35.

EXAMPLE 10: 2, 4-Diamino-5- (2'-methoxy-5'- (4"-carboxybenzyloxy) benzyl] pyrimidine (9).

Metallic Na (12 mg, 0.5 mmol) was dissolved in absolute EtOH (3 mL), and the solvent was evaporated under reduced pressure and replaced by dry DMSO (2 mL). 3-Morpholinopropionitrile (280 mg, 2.0 mmol) was added, and the mixture was placed in a bath pre-heated to 100 °C, and slowly treated with a solution of 28 (684 mg, 2.0 mmol) in dry DMSO (3 mL). After another 20 min at 100 oc, he reaction mixture was cooled and partitioned between EtOAc and dilute citric acid. The EtOAc layer was concentrated to dryness by rotary evaporation, and the residue was taken up in absolute EtOH (10 mL). Aniline hydrochloride (260 mg, 2.0 mmol) was added, and the reaction mixture was refluxed for 30 min. Separately, guanidine hydrochloride

(478 mg, 5.0 mmol) was added to a solution of metallic Na (161 g, 7.0 mmol) in absolute EtOH (20 mL), and the mixture was swirled for 5 min and added to the foregoing ethanolic solution containing the anilino nitrile adduct. The mixture was refluxed for 18h, then chilled and filtered. The filter cake, which was completely soluble in H2O, was discarded, and the filtrate was evaporated under reduced pressure. The residue was taken up in trifluoroacetic acid (5 mL), the solution was evaporated to dryness, and the residue was suspended in H2O (30 mL) and dissolved by adding 1 NNaOH and stirring for several minutes until the pH was 10. Re- acidification with 10% AcOH produced a solid, which was collected, dried in a lyophilization apparatus (crude yield 720 mg), and purified for elemental analysis and bioassay by preparative HPLC (C 18 silica gel, 18% MeCN in 0.1 M NH4OAc, pH 7.4). Appropriately pooled fractions were concentrated and freeze-dried, and the solid was redissolved in dilute NH40H, and filtered. The filtrate was acidified with 10% AcOH, and the precipitate collected and freeze-dried to obtain 9 as a white solid (60 mg, 8% overall yield from 28); mp 250-251 C ; IR (KBr) v 3330,3170, 1660, 1615sh, 1595sh, 1535,1500, 1460,1380, 1295, 1220 cm-1 ; IH NMR (DMSO)-d6) 8 3.49 (s, bridge CH2 partially overlapped by broad H20 peak), 3.74 (s, OMe, partially overlapped by broad H20 peak), 5.08 (s, 2H benzylic CH2), 5.90 (br s, NH2), 6.20 (br s, NH2), 6.83 (m, 3H, 3'-, 4'-, and 6'-H), 7.37 (s, 1H, pyrimidine 6-H), 7.50 (d, J= 8 Hz, 2H, 2"-and 6"-H), 7.93 (d, J= 8 Hz, 3"-and 5"-H). Anal.

(C2oH2oN404-0. 7AcOH) Calc. C 60.85, H 5.44, N 13.26 ; Found C 60.96, H 5.30, N 12.86.

EXAMPLE 11: 2, 4-Diamino-5- [2'-methoxy-5'- [3- (2"- carboxyphenoxy) propyn-l-yl] benzyl] pyrimidine (10).

Step 1. A mixture of ethyl salicylate (29) (1.66 g, 0.01 mol), K2C03 (2.07 g, 0.015 mol), a catalytic amount of 18-crown-6 (26 mg), and propargyl bromide (1.12 mL, of 80% solution in toluene, calculated to contain 1.19 g, 0. 01 mol) in dry DMF (10 mL) was stirred at room temperature for 20 h. The salts were filtered off, and the solvent was evaporated under reduced pressure in a bath maintained at 50 °C. The

residue was partitioned between EtOAc and H20, and the organic layer evaporated to obtain the propargyl ether 31 (2.1 g) as an oil suitable for use directly in the next step; 1H NMR (CDC13) 8 1.38 (t, J= 7 Hz, 3H, CH2CH3), 2.53 (t, J= 2 Hz), 1H, C=CH), 4.36 (q, J= 7Hz, 2H, CH2CH3), 4.79 (d, J= 2 Hz, 2H, =CCH20), 7.05 (dt, J= 8 Hz, J= 2 Hz, 1H, aryl 4-H), 7.12 (d, J= 8 Hz, 1H, aryl 3-H), 7.47 (dt, J= 8 Hz, J= 2 Hz, 1H, aryl 5-H), 7. 80 (dd, J= 8 Hz, J= 2 Hz, 1H, aryl 6-H).

Step 2. A mixture of propargyl ether 31 (306 mg, 1.5 mmol), iodide 19 (356 mg, 1.0 mmol), (Ph3P) 2PdCl2 (10 mg), Cul (1 mg), and Et3N (3 mL) in dry DMF (3 mL) was heated under N2 at 65 °C for 3 h. The solvent was evaporated under reduced pressure, and the residue triturated with alternating portions of isooctane and H2O.

The residue, consisting of ester 33, was dissolved in 50% EtOH (200 mL) at 50 oc, and treated with Ba (OH) 2-8H20 (947 mg, 3.0 mmol). The mixture was stirred at room temperature for 20 h, whereupon a solution a solution of (NH4) 2CO3 (500 mg, 5 mmol) in H20 (10 mL) was added. After 10 min of vigorous stirring, the solid was removed by filtration and the filtrate was concentrated to a small volume under reduced pressure. Pure product for elemental analysis and bioassay was isolated by preparative HPLC (Clg silica gel, 20% MeCN in 0.1 MNH40Ac, pH 7.4, 280 nm).

The major peak (eluting at 13 min on an analytical C 18 column using the same elution system) was concentrated and freeze-dried, and the residue dissolved in small volume of dilute NH40H. A small amount of insoluble material was filtered off, and the filtrate was chilled and acidified with 10% AcOH. The precipitate was collected and freeze-dried to obtain pure 10 as a white solid (104 mg, 24%); mp 147-153 C (softening rather than giving a true melt); IR (KBr) v 3360,3210, 2960br, 2230,1665, 1605,1595, 1560,1505, 1355, 1385, 1295,1275sh, 1250 cm-1 ; 1H NMR (DMSO-d6) 8 3.51 (s, bridge CH2, partly overlapped by broad H2O peak), 3.82 (s, OMe, partly overlapped by broad H20 peak), 5.05 (s, 2H, CH20), 5.94 (br s, NH2), 6.23 (br s, NH2), 6.95-7. 55 (complex m, 7H, aryl and pyrimidine protons), 7.62 (d, J= 7H, 1H 3"-H). Anal. (C22H20N404-1. 5H20) Calc. C 61.25, H 5. 37, N 12.99 ; Found C 61.23, H 5.25, N 12. 81.

EXAMPLE 12: 2, 4-Diamino-5- [2'-methoxy-5'- [3- (3"-carboxyphenoxy)-l- propynyl] benzyl] pyrimidine (11).

Step 1. A mixture of ethyl 3-hydroxybenzoate (30) (1.66 g, 0.01 mol), K2C03 (2.07 g, 0.015 mol), a catalytic amount ofl8-crown-6 (26 mg), and propargyl bromide (1.12 mL 1.49 g of 80% solution in toluene, calculated to contain 0. 01 mol) in dry DMF (10 mL) was stirred at room temperature for 20 h. The salts were filtered off, and the solvent was evaporated under reduced pressure in a bath maintained at 50 OC.

The residue was partitioned between EtOAc and H20, and the organic layer evaporated to obtain the propargyl ether 32 (2.3 g) as an oil suitable for use directly in the next step; 1H NMR (CDC13) 8 1.39 (t, J= 7 Hz, 3H, CH3CH2), 2.53 (d, J= 1 Hz, 1H, C=CH), 4.38 (q, J= 7 Hz, 2H, CH3CH2), 4.74 (s, 2H, =CCH2O), 7.17 (d, J= 8 Hz, 1H, aryl 4-H), 7.36 (t, J= 8 Hz, 1H, aryl 5-H), 7.65 (m, 2H, aryl 2-and 6-H).

Step 2. A mixture of propargyl ether 32 (306 mg, 1. 5 mmol), iodide 19 (356 mg, 1.0 mmol), (Ph3P) 2PdCl2 (10 mg), CuI (1 mg), and Et3N (3 mL) in dry DMF (3 mL) was heated under N2 at 65 OC for 3.5 h. The solvent was evaporated under reduced pressure, and the residue was triturated with alternating portions of isooctane and H20. The solid, consisting of ester 34, was collected and dissolved in DMSO (5 mL) with slight warming as needed. This solution was then swirled and treated dropwise with a solution of NaOH (120 mg, 3.0 mmol) in H20 (1 mL). The mixture was diluted to 90 mL with H20, then brought to approximately pH 8 with 10% AcOH. Pure 9 for microchemical analysis and bioassay was isolated by preparative HPLC (Clg silica gel, 20% MeCN in 0.1 MNH40Ac, pH 7.4, 280 nm).

Appropriately pooled eluates were concentrated and freeze-dried, the residue was re- dissolved in 0.1 NNaOH, and the solution was filtered. Acidification with 10% AcOH, followed by freeze-drying, yielded pure 9 as a white powder (100 mg, 21%); mp 149-153 OC (softening without giving a true melt); IR (KBr) v 3360,3200, 2960 (broad), 1670,1610, 1560,1505, 1460,1445, 1390,1275, 1245 cm-1 ; 1H NMR (DMSO-d6) 8 3.51 (s, benzylic CH2, partly overlapped by broad H20 peak), 3.82 (s,

OMe, partly overlapped by broad H20 peak), 5.04 (s, 2H, CH20), 5.94 (br s, NH2), 6.21 (br s, NH2), 6.99 (d, J= 8 Hz, 1H, 3'-H), 7.11 (d, J= 2 Hz, 1H, 6'-H), 7.21 (dd, J = 8 Hz, J= 2 Hz, 1H, 4'-H), 7. 28-7. 45 (m, 3H, 5"-and 6"-H, pyrimidine 6-H), 7.54 (m, 2H, 2"and 4"-H). Anal. (C22H20N404 AcOH 1. 25H2O) Calc. C 59.19, H 5.48, N 11.50 ; Found C 58.96, H 5.21, N 11.52.

EXAMPLE 13: 6- [5- (2, 4-Diamino-pyrimidin-5-ylmethyl)-2, 3-dimethoxy- phenyl]-hex-5-ynoic acid (Compound 35).

2, 4-Diamino-5- (3'-iodo-4', 5'-dimethoxy-benzyl) pyrimidine (51). A solution of sodium methoxide was prepared by dissolving 46 mg (2.0 mmol) of sodium metal in 3 mL of absolute methanol. The solvent was evaporated under reduced pressure, the residue was dissolved in 5 mL of dimethylsulfoxide, 1.40 g (0.01 mol) of 3- morpholinopropionitrile was added. The mixture was placed in a 100 °C oil bath, a solution of 2.92 g (0.01 mol) of 2, 4-dimethoxy-6-iodobenzaldehyde in 5 mL of dimethylsulfoxide was added slowly, and heating was continued for 20 min. After cooling, the mixture was partitioned between ethyl acetate and water containing 200 mg of citric acid. The organic layer was evaporated, the residue, consisting of morpholinonitrile 50, was then dissolved in 20 mL of absolute ethanol, solid aniline hydrochloride was added, and the solution was refluxed for 20 min.

Separately, a solution of sodium ethoxide was prepared by dissolving 0.69 g (0.03 mol) of sodium metal in 50 mL of absolute ethanol. Then 1.43 g (0.015 mol) of guanidine hydrochloride was added, and the mixture was swirled for 5 min and combined with the solution of 50 prepared above. The mixture was refluxed for 6.5 h, then chilled to-30 °C until a copious solid formed, which was collected and stirred with 40 mL of water to remove sodium chloride. The washed solid was then freeze- dried to obtain 0.65 g of crude 51. Recrystallization from 95% EtOH gave 541 mg of off-white solid, mp 219-220 °C ; NMR (DMSO-d6) 8 1.01 (t, J= 8 Hz, 2H, CH3, ca.

0.67 EtOH of crystallization), 3.41 (p, J= 8 Hz, <2H, CH3, ca 0.67 EtOH of crystallization), 3.48 (s, 2H, bridge CH2), 3.62 (s, 3H, MeO), 3.74 (s, 3H, MeO), 4.29 (t, J= 5Hz, OH of EtOH), 5.66 (br s, 2H, NH2), 6.06 (br s, 2H, NH2), 6.94 (s, 1H, phenyl), 7.10 (s, 1H, phenyl), 7.52 (s, lH, pyrimidine).

2, 4-Diamino-5- [3', 4'-dimethoxy-5'- (5-carboxy-1-pentynyl) benzyl]-pyrimidine (49).

Step 1. A solution of 1.96 g (0.02 mol) of 5-pentynoic acid in 25 mL of dimethylformamide was stirred with 3.25 g (0.01 mol) cesium carbonate for 10 min, followed by addition of 3.42 g (2.38 mLO, 0.02 mol) of benzyl bromide. After 18 h at room temperature, the solvent was evaporated and the residue partitioned between ethyl acetate and water. Evaporation of the organic layer afforded 4.29 g of impure benzyl 5-pentynoate which was used directly in the next step (the NMR spectrum indicate that the impurity was unreacted benzyl bromide).

Step 2. A mixture of 240 mg (0.62 mmol) of 51 (dried at 75 °C in vacuo over phosphorous pentoxide) 202 mg (1.0 mmol) of benzyl 5-hexynoate from the preceding step, 10 mg of dichlorobis (triphenylphosphine) palladium (II) and 10 mg of bromotris (triphenylphosphine) copper (II) in 3 mL of dimethylformamide and 3 mL of triethylamine was heated at 65 °C for 18 h under nitrogen. The solvent was evaporated and the residue was swirled with isooctane, which was then decanted. The residue was dissolved in 3 mL of dimethylsulfoxide and treated dropwise with 2 mL of 2M sodium hydroxide. The solution was then diluted to 40 mL with water and a small amount of undissolved solid was filtered off. The filtrate was adjusted to pH 9.4 with 10% acetic acid. HPLC (Luna Clg silica gel, 15% MeCN in 0.1 M NH40H, H 7.4, 1.0 ml/min 280 nm) showed 49 as the major peak Rf 13 min. Preparative HPLC was performed with the same eluent system except that the acetonitrile concentration was gradually increased from 12% initially to 15% at the end. The pooled eluates were concentrated and freeze-dried. The residue was dissolved in dilute NaOH, filtered, and acidified with 10% acetic acid. Although the product did not precipitate immediately, a solid finally formed after 15 min when the solution was chilled. The mixture was frozen and thawed in order to improve the granularity of the precipitate, and the resulting solid was collected and freeze-dried, affording 146 mg (58%) of 49 as a white solid, mp 222-224 oc dec ; IR (KBr) 3580, 3340, 3160, 2930, 2830w, 1680,1655, 1575,1505, 1485,1460, 1420,1400, 1335,1265, 1230,1180, 1140, 1120, 1030, 1000, 945, 805, 770,690, 650 cm~l, NMR (DMSO-d6) 6 1. 68 (p, J = 7 Hz, 2H, C-3 CH2), 1.84 (s, <1H, CH3COOH), 2.39 (m overlapping DMSO, C-2 and C-4 CH2), 3.49 (s overlapping H20, bridge CH2), 3.64 (s, 3H, MeO), 3.69 (s, 3H,

MeO), 5.66 (s, 2H, NH2), 6.03 (s, 2H, NH2), 6.03 (s, 1H, phenyl), 6.61 (s, 1H, phenyl), 7.48 (s, 1H, pyrimidine).

Anal : Calcd for ClgH22N404 0. 25CH3COOH 1. 75H20: C, 56.17 ; H, 6.41 ; N, 13.44. Found: C, 56.22 ; H, 6.13 ; N, 13.40.

EXAMPLE 14: Enzyme assays and data analysis.

Standardized spectrophotometric determination of Pc, Tg, Ma, and rat liver DHFR inhibition was performed as described previously. ICI values were obtained with the aid of the curve-fitting program Prism 3.0. The data were transformed to % of uninhibited control for enzyme activity (y-axis) and the log of the molar drug concentration (x-axis). The analyses for individual curves had degrees of freedom ranging from 6 (2 curves) to 42 (1 curve); the mode for degrees of freedom was 12 (14 curves). The r2 value for individual curves, determined using the program InStat 2.03, ranged from 0.71 (1 curve) to >0.99 (24 curves); all but two curves had r2 values of >0. 93. The range of SI values for each compound was calculated from the 95% confidence intervals for the individual ICso values for that compound; all were referenced to rat liver DHFR. As an example of the reproducibility of these methods, when lb was assayed against Pc DHFR on three independent occasions, the mean E SEM (standard error of the mean) was found to be 0.054 i 0.0023 uM (i. e., the SEM was 4. 3% of the mean). In quality control assays using TMP against the same enzyme, the SEM was 6.3% of the mean.