Non-glutamate Type Pyrrolo[2, 3-d]pyrimidine Antifolates. III. Synthesis and Biological Properties of Nω-Masked Ornithine Analogs

The glutamic acid moiety of N-[4-[3(2, 4-diamino-7H-pyrrolo[2, 3-d]pyrimidin-5-yl)propyl]benzoyl]-L-glutamic acid (1b, TNP-351) and the related compound (1a), was replaced with various Nω-acyl-, sulfonyl-, carbamoyl- and aryl-2, ω-diaminoalkanoic acids, and the inhibitory effects of the resulting products (9, 11, 14, 18, 21, 23, 25, 30, 36) on dihydrofolate reductase (DHFR), the growth of murine fibrosarcoma Meth A cells, and methotrexate-resistant human CCRF-CEM cells, were examined. Compounds (9a-f) acylated with a hemiphthaloyl group were efficiently synthesized by coupling pyrrolo[2, 3-d]pyrimidine carboxylic acids (7a, b) and Nω-phthaloyl 2, ω-diaminoalkanoic acid methyl esters (6a-c) and subsequent hydrolysis. The other Nω-acyl- and sulfonyl-ornithine analogs (21, 23, 25) were synthesized by acylation of free amino intermediates (19a, b) derived from tert-butoxycarbonyl-ornithine analogs (17a, b). A free ornithine analog (18) did not strongly inhibit Meth A cell growth, whereas all Nω-acyl-, sulfonyl-, carbamoyl- and aryl-ornithine analogs (9, 11, 21, 23, 25, 30, 36) exhibited much more potent inhibitory activities against both DHFR and Meth A cell growth. In particular, compounds 9c, 21k and 36a also showed remarkable growth-inhibitory activities against methotrexate-resistant CCRF-CEM cells. These results demonstrate that the potent inhibitory activities of Nω-masked ornithine analogs against the growth of Meth A cells and methotrexate-resistant CCRF-CEM cells, results from effective uptake via reduced folate carrier and their potent DHFR inhibition.