Design Synthesis and Biological Evaluation of Classical and Nonclassical 2-Amino-4-oxo-5-substituted-6-methylpyrrolo32-dpyrimidines as Dual Thymidylate Synthase and Dihydrofolate Reductase Inhibitors

摘要

We designed and synthesized a classical antifolate N-{4-[(2-amino-6-methyl-4-oxo-3,4-dihydro-5H-pyrrolo[3,2-d]pyrimidin-5-yl)methyl]benzoyl}-l-glutamic acid >4 and 11 nonclassical analogues >5–>15 as potential dual thymidylate synthase (TS) and dihydrofolate reductase (DHFR) inhibitors. The key intermediate in the synthesis was N-(4-chloro-6-methyl-5H-pyrrolo[3,2-d]pyrimidin-2-yl)-2,2-dimethylpropanamide, >29, to which various 5-benzyl substituents were attached. For the classical analogue >4, the ester obtained from the N-benzylation reaction was deprotected and coupled with diethyl l-glutamate followed by saponification. Compound >4 was a potent dual inhibitor of human TS (IC50 = 46 nM, about 206-fold more potent than pemetrexed) and DHFR (IC50 = 120 nM, about 55-fold more potent than pemetrexed). The nonclassical analogues were marginal inhibitors of human TS, but four analogues showed potent T. gondii DHFR inhibition along with >100-fold selectivity compared to human DHFR.