A green one-pot process for the synthesis of 1,2,4-triazole-fused heterocycles using FeBr3 catalyst and hydrogen peroxide

Abstract

An environmentally benign oxidative cyclization utilizing FeBr3 catalyst and hydrogen peroxide as terminal oxidant is devised for one-pot synthesis of 1,2,4-triazole-fused heterocycles from commercially available aliphatic or (hetero)aromatic aldehydes and 2-hydrazinopyridine derivatives. The protocol features mild conditions, simple operation, air/water tolerance, short reaction time, and waste prevention, and has been demonstrated by the synthesis of 32 examples of 1,2,4-triazole-fused heterocycles bearing different substituents in moderate to excellent yields.