Heterocyclization of oximes of 3,5-dimethyl(1,3,5-trimethyl)-2,6- diphenylpiperid-4-ones and N-benzylpyrrolid-3-ones with acetylene in a superbasic medium

It has been established that on heterocyclization of 3,5-dimethyl-2,6- diphenylpiperid-4-one oxime with acetylene in a superbasic medium migration of the 3a-CH3 group to the anionic nitrogen atom occurs, leading to the formation of 5,7-dimethyl-4,6-diphenyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine. The formation of the N-anion causes aromatization of the tetrahydropyridine ring. Tetrahydropyrrolo-[1,2-c]pyrimidines are formed in the Trofimov reaction as a result of decomposition of the intermediate 3H-pyrrole in a retro-Mannich reaction.