Syntheses of partially hydrogenated [1,2,4]triazolo[4,5-a]pyrimidine-4-ones through cyclisation of 2-arylidenehydrazino-6-methyl-4-pyrimidones

3-Arylsubstituted derivatives of 2H,3H,4H,7Hand 1H,2H,3H,4H-[1,2,4]triazolo [4,5a]pyrimidin-4-ones were synthesized from 2-arylidenehydrazino-6-methyl-4-pyrimidones by treatment with acetic anhydride.The structures of the starting compounds and of the isomeric di-N-acetylated reaction products were established by NMR.