Halogeno-o-phenylenediamines and derived heterocycles. Part I. Reductive fission of benzotriazoles to o-phenylenediamines

Abstract

4,5,6,7-Tetrachlorobenzotriazole and its 1-hydroxy-derivative have been reduced with zinc and hydrochloric acid to give 3,4,5,6-tetrachloro-o-phenylenediamine (II; R = Cl) in good yield. The corresponding diamines (II; R = Me or F) were obtained similarly from 4,5,7-trichloro-6-methyl(or fluoro)benzotriazole. Alternative syntheses of the tetrachloro- and methyltrichloro-phenylenediamines are described. Benzimidazoles, quinoxalines, and other heterocycles derived from the diamines, especially from tetrachloro-o-phenylenediamine, are reported.