Novel ring transformations of 5-cyanouracils into 2-thiocytosines, 2,4-diaminopyrimidines, and pyrimido[4,5-d]pyrimidines by the reaction with thioureas and guanidines
Abstract
The reaction of 5-cyanouracils with thioureas and guanidines causes novel pyrimidine-to-pyrimidine ring transformations. Thus, 1,3-disubstituted 5-cyanouracils (1) react with thiourea and guanidines to give the corresponding 5-carbamoyl-2-thiocytosines (2) and 2,4-diamino-5-carbamoylpyrimidines (5), respectively. On the other hand, 5-cyanouracils (8) possessing a phenyl group at the 1-position react with thioureas to give 7-aminopyrimido[4,5-d]pyrimidine-2,4-diones (9).