Synthesis of 1-aryl-1H-indazoles via a ligand-free copper-catalyzed intramolecular amination reaction

Abstract

A general synthesis of 1-aryl-1-H-indazoles from o-halogenated aryl aldehydes or ketones and aryl hydrazines was described. This protocol included an intermolecular condensation and a ligand-free copper-catalyzed intramolecular Ullmann-type coupling reaction. This method was applied to a wide range of substrates to produce the indazole products in good yields. Copyright © 2011 SIOC, CAS, Shanghai & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.