.alpha.-Regioselectivity in palladium-catalyzed arylation of acyclic enol ethers

Regioselective α-arylation of acyclic enol ethers by aryl trifluoromethanesulfonates, aryl bromide, aryl iodides, and aroyl chlorides is described. The outcome of the reaction proved to be dependent from the relationship between ligand and counterion in the oxidative addition complex