Pd-Catalyzed Umpolung of η³-Benzylpalladium Enabled the Construction of All-Carbon α-Vinyl Quaternary Aldehydes

A Pd-catalyzed decarboxylative approach for the construction of 2-allyl-2,2-diarylacetaldehydes via dearomative umpolung strategy is reported. The reaction is applicable to a number of cyclic carbonates or allylic acetates featuring with different functional groups. These reactions could be performed in a gram-scale but without loss of the reaction efficiency. The control experiments suggest that the reaction proceeds though a palladium catalyzed dearomative decarboxylation step followed by an umpolung nucleophilic attack. (Figure presented.).