Vinylogous Reactivity of Enol Diazoacetates with Donor-Acceptor Substituted Hydrazones. Synthesis of Substituted Pyrazole Derivatives

A regiospecific synthesis of multifunctional pyrazoles has been developed from a cascade process triggered by Rh(II)-catalyzed dinitrogen extrusion from enol diazoacetates with vinylogous nucleophilic addition followed by Lewis acid catalyzed cyclization and aromatization.