Heck arylation of alkenes with aryl bromides by using supported Pd catalysts: a comparative study

Abstract

Supported Pd catalysts were investigated in the Heck coupling reactions: Pd/C; Pd/BaSO4; Pd EnCat. We optimized the experimental conditions of the Heck reaction of bromobenzene and styrene by using various bases in the presence of quaternary ammonium salts. It was found that the examined catalysts work as a reservoir of the catalytically active Pd species during the reaction. However, they have a different activity and recyclability under the investigated reaction conditions. Pd EnCat displayed the highest activity and selectivity in NMP with Na2CO3 as a base and Bu4NCl as an additive. By using this catalytic system, the reactions of para-substituted aryl halides with styrene and methyl methacrylate afforded excellent conversions and selectivities.