Itami Kenichiro, Mitsudo Koichi, Nishino Akira, Yoshida Jun-ichi
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Yoshida, Kyoto 606-8501, Japan.
J Org Chem. 2002 Apr 19;67(8):2645-52. doi: 10.1021/jo0163389.
Metal-catalyzed hydrosilylation of alkenes and alkynes using dimethyl(pyridyl)silane is described. The hydrosilylation of alkenes using dimethyl(2-pyridyl)silane (2-PyMe(2)SiH) proceeded well in the presence of a catalytic amount of RhCl(PPh(3))(3) with virtually complete regioselectivity. By taking advantage of the phase tag property of the 2-PyMe(2)Si group, hydrosilylation products were isolated in greater than 95% purity by simple acid-base extraction. Strategic catalyst recovery was also demonstrated. The hydrosilylation of alkynes using 2-PyMe(2)SiH proceeded with a Pt(CH(2)=CHSiMe(2))(2)O/P(t-Bu)(3) catalyst to give alkenyldimethyl(2-pyridyl)silanes in good yield with high regioselectivity. A reactivity comparison of 2-PyMe(2)SiH with other related hydrosilanes (3-PyMe(2)SiH, 4-PyMe(2)SiH, and PhMe(2)SiH) was also performed. In the rhodium-catalyzed reaction, the reactivity order of hydrosilane was 2-PyMe(2)SiH >> 3-PyMe(2)SiH, 4-PyMe(2)SiH, PhMe(2)SiH, indicating a huge rate acceleration with 2-PyMe(2)SiH. In the platinum-catalyzed reaction, the reactivity order of hydrosilane was PhMe(2)SiH, 3-PyMe(2)SiH >> 4-PyMe(2)SiH > 2-PyMe(2)SiH, indicating a rate deceleration with 2-PyMe(2)SiH and 4-PyMe(2)SiH. It seems that these reactivity differences stem primarily from the governance of two different mechanisms (Chalk-Harrod and modified Chalk-Harrod mechanisms). From the observed reactivity order, coordination and electronic effects of dimethyl(pyridyl)silanes have been implicated.
描述了使用二甲基（吡啶基）硅烷对烯烃和炔烃进行金属催化的硅氢化反应。在催化量的RhCl(PPh₃)₃存在下，使用二甲基（2 - 吡啶基）硅烷（2 - PyMe₂SiH）对烯烃进行的硅氢化反应进行顺利，区域选择性几乎完全。利用2 - PyMe₂Si基团的相标签性质，通过简单的酸碱萃取可分离出纯度大于95%的硅氢化产物。还展示了策略性的催化剂回收。使用2 - PyMe₂SiH对炔烃进行的硅氢化反应在Pt(CH₂=CHSiMe₂)₂O/P(t - Bu)₃催化剂作用下进行，以良好的产率和高区域选择性得到烯基二甲基（2 - 吡啶基）硅烷。还对2 - PyMe₂SiH与其他相关硅烷（3 - PyMe₂SiH、4 - PyMe₂SiH和PhMe₂SiH）进行了反应活性比较。在铑催化的反应中，硅烷的反应活性顺序为2 - PyMe₂SiH >> 3 - PyMe₂SiH、4 - PyMe₂SiH、PhMe₂SiH，表明2 - PyMe₂SiH的反应速率大幅加快。在铂催化的反应中，硅烷的反应活性顺序为PhMe₂SiH、3 - PyMe₂SiH >> 4 - PyMe₂SiH > 2 - PyMe₂SiH，表明2 - PyMe₂SiH和4 - PyMe₂SiH的反应速率减慢。这些反应活性差异似乎主要源于两种不同机理（Chalk - Harrod和改进的Chalk - Harrod机理）的作用。从观察到的反应活性顺序来看，二甲基（吡啶基）硅烷的配位和电子效应已被涉及。
