Studies on fused pyrimidine derivatives. Part 12. Reaction of 6-(alk-2-enylamino)-5-formyl-1,3-dimethylpyrimidine-2,4(1H,3H)-diones with α-amino acid derivatives

The reactions of 6-(alk-2-enylamino)-5-formyl-1,3-dimethylpyrimidine-2,4(1H,3H)-diones 1 with α-amino acid derivatives are described. The reaction of compounds of 1 with N-substituted amino acid derivatives affords azomethine ylides through well known condensation processes. A similar reaction with N-unsubstituted amino acid derivatives gives pyrimido[4,5-b]azepine derivatives via an intramolecular ene reaction of the imines, obtained from diones 1 and N-unsubstituted amino acid derivatives. The reaction profiles depend upon the N-substituent patterns of the amino acid derivatives utilised.