Regiocontrolled [5,5]-sigmatropic rearrangement reaction of aryl hydrazides for efficient synthesis of benzidines

Abstract

N,N’-Aryl hydrazides with substituents at the ortho- or meta-positions undergo highly regioselective [5,5]-sigmatropic rearrangement reactions to furnish benzidines in good to excellent isolation yields. The presence of single substituent at either ortho- or meta-position provides sufficient bias, effectively suppressing the formation of diphenylene, the major byproduct of the conventional benzidine rearrangement reaction.