Catalytic hydrogenation of 3-benzyloxycarbonylaminoazino[1,2-x]-azin-4-ones.: A facile access to 3-amino-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyridin-4-ones and 3-amino-6,7,8,9-tetrahydro-4H-azino[1,2-x]pyrimidin-4-ones

By catalytic hydrogenation of 3-(benzyloxycarbonyl)amino-4H-pyrido[1,2-a]pyridin-4-ones 28 and 29, and azino[1,2-x]pyrimidin-4-ones 32-35, 41, and 42, partial saturation of the heterocyclic systems and removal of the benzyloxycarbonyl moiety was observed to give 3-amino-6,7,8,9-tetrahydro-4H-pyrido[1,2 a]pyridin-4-ones 30 and 31, and 3-amino-6,7,8,9-tetrahydro-4H-azino[1,2-x]pyrimidin-4-ones 36-39, 43, and 44 in high yields. The methods represent a simple two step synthesis, starting from heterocyclic alpha-amino compounds and methyl (Z)-2-(benzyloxycarbonyl)amino-3-dimethylaminopropenoate followed by catalytic hydrogenation.