Palladium-Catalyzed Oxidative Cascade Carbonylative Spirolactonization of Enallenols

Abstract

A highly selective palladium-catalyzed oxidative carbonylation/carbocyclization/alkoxycarbonylation of enallenols to afford spirolactones bearing an all-carbon quaternary center was developed. This transformation involves the overall formation of three C-C bonds and one C-O bond through a cascade insertion of carbon monoxide (CO), an olefin, and CO. Preliminary experiments on chiral anion-induced enantioselective carbonylation/carbocyclization of enallenols afforded spirolactones with moderate enantioselectivity.

Keywords: carbocyclization; enallenols; oxidation; palladium; spirolactones.