Cyclization reactions of 3‐hydrazino[1, 2, 4]triazino[5, 6‐<i>b</i>]indole

Abstract

Abstract The reaction of 3‐hydrazino[1, 2, 4]triazino[5, 6‐ b ]indole I with nitrous acid affords the azide III which could be cyclized with acetic anhydride to 10‐acetyl‐10 H ‐tetrazolo[5′,1′:3, 4][1, 2, 4]triazino[5, 6‐ b ]indole IIb . Cyclization reactions of I with acetic anhydride, ethyl chloroformate, carbon disulphide and aromatic aldehydes to the corresponding fused triazolo derivatives V–VIII are reported. On the other hand cyclization reactions of I with malononitrile, ethyl cyanoacetate, ethyl acetoacetate and acetylacetone to the corresponding condensed pyrazolino derivatives IX–XI are also reported. The reaction of I with α‐dicarbonyl compounds to form mono and dihydrazones are reported. The structure of the compounds prepared and their cyclization mechanisms are reported.