Intramolecular oxycyanation of alkenes by cooperative Pd/BPh3 catalysis.

The cooperative catalysis by palladium and triphenylborane effects the intramolecular oxycyanation of alkenes through the cleavage of O–CN bonds and the subsequent insertion of double bonds. The use of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) as a ligand for palladium is essential for allowing the transformation to proceed with high chemo- and regioselectivity. Variously substituted dihydrobenzofurans with both a tetra-substituted carbon and cyano functionality are accessed by the newly developed methodology.