The cross-metathesis of styrene with various vinylsilanes,H2C=C(H)SiR3, catalyzed by [Cl-2(PC(y)3)(2)Ru=CHPh] (1) to give (E)-silylstyrene, (E)-Ph(H)C=C(H)SiR3, and ethylene is reported. The reaction proceeds even at room temperature and is highly selective. Very high conversions are observed when R = OEt, OSiMe3 (greater than or equal to 95%, 6 h, 2 mol % of 1). The conversion significantly decreases with increasing substitution of Me for OR'. The metathesis is reversible. Therefore, removal of ethylene is critical for achieving high conversions. From the study of stoichiometric reactions of 1 with vinylsilanes it follows that in the series SiR3 = Si(OEt)(3), SiMe(OEt)(2), SiMe2OEt, SiMe3 and SiR3 = Si(OSiMe3)(3), SiMe(OSiMe3)(2), SiMe2(OSiMe3), SiMe3 the conversion rate increases, but simultaneously the selectivity of the metathesis decreases. The decreasing selectivity readily accounts for the decreasing efficiency in the catalytic metathesis. The product distribution of reactions of styrene-d(s) with H2C= C(H)SiR3 (R = OEt, OSiMe3) in the presence of 1 provides evidence for a metallacarbene mechanism involving [Ru]=CHPh and [Ru]=CH2 species.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据