Reaction of 4,5,6-triaminopyrimidine and 2,4,5,6-tetraaminopyrimidine with 3-dimethylaminopropiophenones. Synthesis of new 4-aryl-2,3-dihydropyrimido[4,5-b][1,4]diazepines

Abstract

Several new 6-amino- and 6,8-dinmino-4-aryl-2,3-dihydropyrimido[4,5-b][1,4]diazepines were obtained from the reaction of 4,5,6-triaminopyrimidine 1a and 2,4,5,6-tetraaminopyrimidine 1b with one equivalent of 3-dimethylaminopropiophenones 2 in absolute ethanol. Structure analysis of 6-amino- and 6,8-diamino-4-aryl-2,3-dihydropyrimido[4,5-b][1,4]diazepines 3a-i, determined by detailed nmr measurements, reveals a high regioselectivity of this reaction.