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 uracilspossessing an electron-withdrawinggroup 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 exchangereactions were influenced by the nature of substituents at the 5- and N1-position. The reaction sequence is explained in terms of addition, ring-opening
The reaction of 6-amino-5-formyl (or acetyl) uracils (4) possessing a phenyl group at the 1-position with caustic alkali resulted in Dimroth rearrangement to give 6-anilino-5-formyl (or acetyl) uracils (5). This is the first example of Dimroth rearrangement observed in the uracil ring system. The presence of both the N1-phenyl group and the 5-formyl (or acetyl) group on the uracil ring is requisite for the occurrence of the rearrangement.