Direct C–H Alkenylation of Functionalized Pyrazoles

Abstract

We have developed inter- and intramolecular C-H alkenylation reactions of pyrazoles. The catalyst, derived from Pd(OAc)2 and pyridine, enabled the oxidative alkenylation of pyrazoles containing a variety of functional groups at the C4 position. Activated alkenes, including acrylate, acrylamide, and styrene derivatives, and enamides could be installed in this process. The sequential C-H alkenylation and cyclization reactions gave rise to fused bicyclic pyrazoles, providing a new strategy to annulate readily available pyrazole compounds.