Amination of the pyridinium cations in betaines. Synthesis of substituted pyrimido[5,6-c]-1′-azaquinolizine and its dihydro analogs

The pyridinium cations within betaines can be aminated under mild conditions with aqueous ammonia, ultimately undergoing cyclization to a new tricyclic system: 4-substituted-3,5-dioxopyrimido5,6-c]-1-azaquinolizine. Intermediates in the reaction are 4-substituted-3,5-dioxo-2,2-dihydropyrimido5,6-c]-6H-1-quinolizines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 677–680, May, 1987.