Coupling Reactions of α-Bromoalkenyl Phosphonates with Aryl Boronic Acids and Alkenyl Borates

Transition metal-catalyzed arylation and alkenylation of the α-bromoalkenyl phosphonates were investigated with organoboranes and -borates. Arylation was successful with the aryl boronic acids and a palladium catalyst, while alkenylation was found to proceed with alkenyl borates and a nickel catalyst. In addition, an intramolecular Diels−Alder reaction of the diene prepared by the alkenylation afforded the corresponding adduct.