Pyrimidine derivatives and related compounds. Part 50. Photochemical reaction of 5-substituted 6-azido-1,3-dimethyluracils with nucleophiles. Ring transformation of pyrimidine to 1,3,5-triazepine and hydantoin ring systems
Abstract
Photolysis of 5-substituted 6-azidouracil derivatives in the presence of nucleophiles has been studied. Irradiation of 5-alkyl-6-azidouracils (3) in the presence of amines caused a ring expansion to give 1,3,5-triazepine derivatives (7). Photolysis of 6-azido-1,3,5-trimethyluracil (3a) in alcohols gave the corresponding 6,6-dialkoxy-5-amino-5,6-dihydrouracils (8). When compound (3a) was irradiated in water, a ring contraction occurred to afford 3,5-dimethylhydantoin (9). On the other hand, 6-azido-5-cyano-1,3-dimethyluracil (4) was converted into 1,3,5-triazepines (13) only in the presence of alcohols.