A four-step cascade reaction involving O[1,3] sigmatropic shift and Smiles rearrangements as key steps

Abstract

A new cascade aromatic nucleophilic substitution-O[1,3] sigmatropic shift-Smiles rearrangement-amide and ester exchange reaction of 2/4-nitroaryl halides and N-acyl-N-arylhydroxylamines was observed and investigated in the presence of sodium hydride in THF, affording 2-((2/4-nitroaryl)amino)aryl carboxylate derivatives in low to excellent yields depending upon the electrophilicity of 2/4-nitroaryl halides. Generally, aryl halides with strong electron-withdrawing 2,4,6-trisubstituents gave the rearranged products in satisfactory to excellent yields. The current reaction provides not only an unprecedented cascade four-step reaction, but also a new strategy for the synthesis of 2-hydroxydiarylamine derivatives under transition metal-free conditions.