Vinylogous reactivity of enol diazoacetates with donor-acceptor substituted hydrazones. Synthesis of substituted pyrazole derivatives.

A regiospecific synthesis of multifunctional pyrazoleshas 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.