Visible-Light-Promoted Regio- and Stereoselective Oxyalkenyl-Ation of Phosphinyl Allenes

A highly regio- and stereoselective oxyalkenylation of phosphinyl allenes is revealed for the first time. This protocol, merging visible light photoredox and palladium catalysis, provides a direct approach to conjugated tertiary allylic alcohol derivatives with broad functional group tolerance in moderate to excellent yields. Mechanistic studies suggest that, although two possible pathways exist in the transformation, radical oxyalkenylation promoted by visible light photoredox takes over the major pathway.