Cyclization of Substituted 3,4-Diaminopyridines into 1H-[1,2,3]Triazolo[4,5-c]pyridine 2-Oxide Derivatives during the Nitration Process

The nitration of pyridine-3,4-diamine, its N,N'-diacetyl derivative, and N(4)-alkylpyridine-3,4-diamines with excess nitric acid in concentrated sulfuric acid at 60 degrees C was accompanied by cyclization with formation of the corresponding 1-substituted 4-nitro-1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxides. 4-Chloro-1H-[1,2,3] triazolo[4,5-c] pyridine 2-oxide derivatives were obtained under analogous conditions from 2-chloropyridine-3,4-diamine, its N, N'-diacetyl derivative, and 2-chloro-N(4)-methylpyridine-3,4-diamine. The nitration of these compounds at 80-90 degrees C gave 4-chloro-7-nitro-1H-[1,2,3] triazolo[4,5-c] pyridine 2-oxides.