Novel reaction of uracil derivatives possessing electron-withdrawing groups at the 5-position with amines: exchange reaction between the N1-portion of uracils and amines

The reaction of 1,3-disubstituted uracils possessing an electron-withdrawing group such as nitro, carbamoyl, and cyano at the 5-position with primary amines resulted in the exchange of the N1-portion of the uracil ring with the amine moiety. The exchange reactions were influenced by the nature of substituents at the 5- and N1-position. The reaction sequence is explained in terms of addition, ring-opening, and ring-closure.