The treatment of 4-benzyloxy-1-butyne with PhMe 2 SiMgMe in the presence of a catalytic amount of MnCl 2 gave a monosilylated product,(E)-PhCH 2 OCH 2 CH 2 CH= CHSiMe 2 Ph, selectively after an aqueous workup. Meanwhile, the reaction of isoprene with PhMe 2 SiMgMe under manganese catalysis and the subsequent addition of iodomethane afforded 4-dimethylphenylsilyl-2, 3-dimethyl-1-butene in good yield.
