Palladium(II)-catalyzed aryl coupling of triarylbismuthines under air

Triarylbismuthines readily reacted with a catalytic amount of palladium(II) acetate in methanol under air to give the corresponding biaryls in high yields. The presence of oxygen was indispensable for this catalytic coupling, biaryl formation being quite slow under nitrogen. Oxygen absorption was observed during the reaction and a Pd-oxygen complex prepared separately worked effectively as a reagent for this coupling even under inert gas.