Highly Regioselective Synthesis of Indene Derivatives Including an Allene Functional Group via Pd/C-Catalyzed Cyclization Reaction in Air

Indene derivatives including an allene functional group are readily prepared in moderate to excellent yields with high regioselectivity under very mild reaction conditions by the Pd/C-catalyzed reaction of propargylic compounds. The resulting products can be further elaborated using Pd-catalyzed annulation reactions.