Monomeric triphenylphosphite palladacycles with N-imidazole ligands as catalysts of Suzuki-Miyaura and Sonogashira reactions

Three monomeric triphenylphosphite palladacycles of the formula [PdCl(P-C)(im)], where P-C - P(OC(6)H(4))(OC(6)H(5))(2), im = 1-methylimidazole, 2, 1,2-dimethylimidazole, 3, and 1-butylimidazole, 4, were obtained in reaction of [PdCl(P-C)](2), 1, with the respective imidazoles. These complexes exhibited high catalytic activity in the Suzuki-Miyaura reaction in ethane-1,2-diol and in the Sonogashira reaction in ionic liquids, [bmim]BF(4) and [bmim]PF(6). While the application of two imidazoles per palladium caused improvement of the reaction yield, an inhibiting effect was found in both reactions when 1-methylimidazole or 1-butylimidazole was used in 20-fold excess relative to palladium. (C) 2011 Elsevier B.V. All rights reserved.