Palladium-catalyzed cross-coupling of aryl and alkenyl boronic acids with alkenes via oxidative addition of a carbonboron bond to palladium(O)

Arylboronic acids react with alkenes in acetic acid at 25°C in the presence of a catalytic amount of palladium(II) acetate together with sodium acetate to give the corresponding aryl-substituted alkenes in high yields. Alkenylboronic acids react with alkenes under similar conditions to give the corresponding conjugated dienes stereospecifically, but the product yields are lower, compared with those from arylboronic acids. Similar treatment of sodium tetraphenylborate (NaBPh₄) with alkenes also affords the corresponding phenylated alkenes in high yields together with biphenyl and benzene as side products. Oxidative addition of a carbonboron bond to palladium(O), formed in situ, to give an organopalladium(II) species is assumed to be the key step of these cross-coupling reactions.