Regioselective multicomponent synthesis of fully substituted pyrazoles and bispyrazoles catalyzed by zinc triflate

Abstract

A variety of fully substituted pyrazoles were easily prepared through a three-component condensation of aldehydes, arylhydrazines, and ethyl acetoacetate in the presence of catalytic amounts of zinc triflate [Zn(OTf) under solvent-free conditions. Selective synthesis of symmetrical and unsymmetrical bispyrazoles from dialdehydes in high yields can be considered as a notable advantage of this method. © Georg Thieme Verlag Stuttgart · New York.