Synthesis of Allylarenes via Catalytic Decarboxylation of Allyl Benzoates

A catalyst system consisting of the palladium(0) complex Pd-2(dba)(3) and tri(p-tolyl)phosphine was found to efficiently promote the decarboxylation of allyl benzoates with formation of allylarenes. This catalytic C-O activation followed by extrusion of carbon dioxide and C-C bond formation represents a sustainable alternative to traditional waste-intensive cross-couplings. The scope of the transformation includes allyl and cinnamyl esters of various ortho-substituted benzoic acids. For particularly activated substrates, the palladium catalyst can optionally be replaced by an inexpensive nickel complex.