cis, cis, cis-1, 2, 3, 4-Tetrakis (diphenylphosphinomethyl) cyclopentane/[PdCl (C3H5)] 2 efficiently catalyses the Heck reaction of β-substituted enol ethers with aryl bromides. Employing β-methoxystyrene, 3-ethoxyacrylonitrile or methyl 3-methoxyacrylate, the regioselective α-arylation of these enol ethers was observed in all cases, and mixtures of Z and E isomers were generally obtained, which in many cases yielded a single ketone ...