Superb efficient and recycle polymer-anchored systems for palladium catalyzed Suzuki cross-coupling reactions in water

A set of three new polymer-anchored palladium(II) Schiff base catalysts have been synthesized, characterized and their catalytic activity was investigated in the Suzuki cross-coupling reaction between aryl halides and arylboronic acid in the presence of Cs2CO3 as a base. They show excellent catalytic activity in coupling of aryl bromides or aryl iodide with phenylboronic acid under the optimized reaction conditions in water. Polymer-anchored Pd(II) complexes provided turnover frequency of 29,700 or 58,200 h(-1) in Suzuki coupling reactions of phenylboronic acid with p-bromoacetophenone or p-iodobenzene, respectively, which are the highest values ever reported for the Suzuki coupling reactions in water as sole solvent. The catalyst 1 could be used for 15 reaction cycles in the Suzuki coupling of p-acetobromobenzene at 100 degrees C with no loss of catalytic activity. (C) 2012 Elsevier B.V. All rights reserved.