Abstract Upon irradiation, 4 (3H)-pyrimidin-4-one (1) afforded a di-imine derivative (2) which, when hydrolyzed in an acidic methanol solution, gave N-methyl acetoacetamide (3). On the other hand, the fused 4 (3H)-pyrimidin-4-ones,(4) and (5), gave medium-ring lactams (6) and (7), which were hydrolyzed in an acidic methanol solution to give (8) and (9), respectively.
