Synthesis of 1-Aryl-1<i>H</i>-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.