Methoxycarbonylation of Styrene Catalyzed by Palladium Complexes with Ferrocene Derivatives Containing Nitrogen and Phosphine Ligands

Abstract

The catalytic behaviour of different complexes of Palladium(II) containing mono or bidentate phosphorus or nitrogen ligands in the methoxycarbonylation reaction is examined. The pre-catalysts containing either a diphosphine ligand possessing a ferrocenyl backbone or a naphthyridine ligand attached to the same ferrocenyl backbone showed different catalytic activity for the reaction. Complexes containing the 1,1-bis(diphenylphosphino)ferrocene (dppf) ligand showed a better catalytic activity than the complex having the naphthyridine ligand in its structure. Various effects of the addition of triphenylphosphine to these pre-catalysts were observed. More than 99% conversion was achieved in the methoxycarbonylation of styrene using Pd(II) catalysts with ferrocenyl chelate derivatives, mostly with the Pd(dppf)Cl2, [Pd(dppf)(MeCN)2](BF4)2 and [Pd(dppf)PPh3](BF4)2 complexes without the presence of triphenylphosphine as is usual in this reaction. The reactions were carried out under mild pressure and temperature conditions. Complexes of the type Pd(dppf)Cl2, [Pd(dppf)(MeCN)2](BF4)2 and [Pd(dppf)PPh3](BF4)2 were used as catalysts for the Methoxycarbonylation of styrene using mild pressure and temperature condition. The catalysts system showed more than 99% conversion in reactions without the presence of triphenylphosphine.