Hydrosilylation of 1-methylcyclopentene

Hydrosilylation of 1-methylcyclopentene with chloromethylsilanes Me3-nSiHCl n (n = 2, 3) yields dichloro(cyclopentylmethyl)methyl- and trichloro(cyclop entylmethyl)silanes, respectively. Chlorodimethyl-silane (n = 1) adds to 1- methylcyclopentene to give a mixture of cis- and trans-chloro(methyl)(2-met hylcyclopentyl)silanes, as well as chloro(cyclopentylmethyl)methylsilane. T he hydrosilylation products were reacted with ethynylmagnesium bromide to p repare the corresponding ethynyl derivatives. Reaction of (cyclopentylmethy l)triethynylsilane with ethylmagnesium bromide and chlorotrimethylsilane ga ve (cyclopentylmethyl)tris(trimethylsilylethynyl)silane.