Synthesis of 6-nitroderivatives of oxazolo[3,2-a]-pyridines and their reactions with nucleophiles

Abstract

5-Nitro-2-pyridone can be selectively N-phenacylated, and the resulting phenacylpyridones I undergo cyclization to 6-nitrooxazolo[3,2-a]pyridinium salts II. These salts II readily react with ammonia and aliphatic amines leading to the products of pyridine ring opening - previously unknown 1-amino-2-nitro-4- (oxazole-2-yl)butadienes-1,3. Reaction of salts II with water lead to hydrolytic cleavage of the oxazole fragment.