Formation of branched silanes via regiospecific hydrosilylation of vinylsilanes

Metallocene complexes of type Cp′2Cp′2MCH(TMS)2 (Cp′ = η5-Me5C5, M = Y, Sm), Me2SiCp″2Cp″2SmCH(TMS)2 (Cp″ = η5-Me4C5) catalyze rapid and clean hydrosilylation of CH2CHSiMe2R (R = Me, Ph, NMe2, OtBu) with PhSiH3. The distribution of 1,2-addition product versus 2,1-addition product was found to be sensitive to both catalysts and substrates. Generation of 2,1-addition product can best be achieved by use of more sterically accessible catalysts as well as substrates containing tethering functional groups. A four-centered transition state is invoked to explain these effects.Figure optionsDownload as PowerPoint slide

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