Selective synthesis of (E)-triethyl(2-arylethenyl)silane derivatives by reaction of aryl bromides with triethyl vinylsilane catalysed by a palladium–tetraphosphine complex

Cis, cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane / 0.5 [PdCl(C3H5)]2 system catalyses the Heck reaction of vinylsilane derivatives with a range of aryl bromides with high ratio substrate/catalyst in good yields. The formation of mixtures of styrene, (E)-triethyl(2-arylethenyl)silane and triethyl(1-arylethenyl)silane derivatives was observed in some cases. Very high selectivities (up to 100%) in favour of the formation of (E)-triethyl(2-arylethenyl)silane derivatives were obtained in the presence of sodium acetate as base. With other bases such as potassium carbonate, the formation of large amounts of styrene derivatives was observed. The reaction tolerates several functions such as fluoro, trifluoromethyl, methoxy, dimethylamino, acetyl, formyl, benzoyl, carboxylate, nitro or nitrile. Moreover, turnover numbers up to 10,000 can be obtained for this reaction.