Copper(ii) ionic liquid catalyzed cyclization-aromatization of hydrazones with dimethyl acetylenedicarboxylate: A green synthesis of fully substituted pyrazoles

Abstract

The Lewis acid room temperature ionic liquid, [n-Bu4P][CuBr 3], was found to be an efficient and reusable catalyst for three component synthesis of fully substituted pyrazoles from the reaction of aldehydes, arylhydrazines and dimethyl acetylenedicarboxylate (DMAD). This catalytic system is simple and chemoselective with high yields. © 2013 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.