An Active and Recyclable Polystyrene-Supported N-Heterocyclic CarbenePalladium Catalyst for the Suzuki Reaction of Arylbromides with Arylboronic Acids under Mild Conditions

A novel polymer-supported imidazolium salt has been prepared from a bisimidazolium salt and cross-linked chloromethyl polystyrene. The polymer-supported N-heterocyclic carbene-palladium complex, generated from the supported bisimidazolium salt and Pd(OAc)2, efficiently catalyzed the Suzuki coupling reaction of aryl bromides and arylboronic acids under air in aqueous DMF solution at room temperature, giving biaryls in good to excellent yields. The catalyst could be reused several times still retaining high activity.