Azinotriazines. I. Synthesis and spectral data of pyrido[3,2-e] -as-triazines

A series of pyrido3,2-e]-as-triazines (VI) was prepared via acid-catalyzed cyclization of suitable 2-substituted 3-aminopyridines obtained by reduction of the corresponding 3-nitro-pyridines. Cyclization of 3-amino-2-hydrazinopyridines (III) with triethyl orthoformate and hydrochloric acid, or cyclodehydration of 2-(2-acetylhydrazino)-3-aminopyridines (IV) with alcoholic hydrogen chloride gave 1,2-dihydropyrido3,2-e]-as-triazine hydrochloride (V). Mild dehydrogenation with alkaline potassium ferricyanide yielded heteroaromatic pyrido3,2-e]-as-triazines (VI), for which ultraviolet and nmr spectral data are reported.