A dideazatetrahydrofolate analog lacking a chiral center at C-6: N-[4-[2-(2-amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5yl)ethyl[benzoyl]-L-glutamic acid is an inhibitor of thymidylate synthase

N-[4-[2-(2-Amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5- yl)ethyl]benzoyl]-L-glutamic acid (15), prepared in five steps from 2-pivaloyl-7-deazaguanine, has been found to be an antitumor agent with its primary site of action at thymidylate synthase rather than purine synthesis. This compound appears to be a promising candidate for clinical evaluation.