Highly Selective Construction of Seven-Membered Carbocycles by Olefin-Assisted Palladium-Catalyzed Oxidative Carbocyclization-Alkoxycarbonylation of Bisallenes

An olefin-assisted palladium-catalyzed oxidative carbocyclization-alkoxycarbonylation of bisallenes to afford seven-membered carbocycles has been established. This dehydrogenative coupling reaction showed excellent substrate scope and functional group compatibility. The reaction exhibited high chemo-and regioselectivity, and ester 3 was the only product obtained. The olefin unit has been proven to be indispensable during the reaction. Moreover, intramolecular oxidative coupling suggests that the reaction proceeds via a (pallyl)palladium intermediate.