Non-Metal-Catalyzed Heterodehydrocoupling of Phosphines and Hydrosilanes: Mechanistic Studies of B(C6F5)3-Mediated Formation of P–Si Bonds,Journal of the American Chemical Society

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Non-Metal-Catalyzed Heterodehydrocoupling of Phosphines and Hydrosilanes: Mechanistic Studies of B(C6F5)3-Mediated Formation of P–Si Bonds
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-11-14 , DOI: 10.1021/jacs.7b09175
Lipeng Wu ₁ , Saurabh S. Chitnis ₁ , Haijun Jiao ₂ , Vincent T. Annibale ₁ , Ian Manners ₁

Affiliation

Non-metal-catalyzed heterodehydrocoupling of primary and secondary phosphines (R1R2PH, R2 = H or R1) with hydrosilanes (R3R4R5SiH, R4, R5 = H or R3) to produce synthetically useful silylphosphines (R1R2P-SiR3R4R5) has been achieved using B(C6F5)3 as the catalyst (10 mol %, 100 °C). Kinetic studies demonstrated that the reaction is first-order in hydrosilane and B(C6F5)3 but zero-order in phosphine. Control experiments, DFT calculations, and DOSY NMR studies suggest that a R1R2HP·B(C6F5)3 adduct is initially formed and undergoes partial dissociation to form an "encounter complex". The latter mediates frustrated Lewis pair type Si-H bond activation of the silane substrates. We also found that B(C6F5)3 catalyzes the homodehydrocoupling of primary phosphines to form cyclic phosphine rings and the first example of a non-metal-catalyzed hydrosilylation of P-P bonds to produce silylphosphines (R1R2P-SiR3R4R5). Moreover, the introduction of PhCN to the reactions involving secondary phosphines with hydrosilanes allowed the heterodehydrocoupling reaction to proceed efficiently under much milder conditions (1.0 mol % B(C6F5)3 at 25 °C). Mechanistic studies, as well as DFT calculations, revealed that PhCN plays a key mechanistic role in facilitating the dehydrocoupling reactions rather than simply functioning as H2-acceptor.

中文翻译：

膦和氢硅烷的非金属催化杂脱氢偶联：B(C6F5)3 介导的 P-Si 键形成的机理研究

伯膦和仲膦（R1R2PH，R2 = H 或 R1）与氢硅烷（R3R4R5SiH，R4，R5 = H 或 R3）的非金属催化杂脱氢偶联，以生产合成有用的甲硅烷基膦（R1R2P-SiR3R4R5）已使用 B(C6F5) 实现)3 作为催化剂 (10 mol%, 100 °C)。动力学研究表明该反应在氢硅烷和 B(C6F5)3 中是一级反应，而在膦中是零级反应。对照实验、DFT 计算和 DOSY NMR 研究表明，R1R2HP·B(C6F5)3 加合物最初形成并经过部分解离以形成“相遇复合物”。后者介导了硅烷基材的受挫路易斯对型 Si-H 键活化。我们还发现 B(C6F5)3 催化初级膦的同型氢偶联形成环膦环，这是非金属催化的 PP 键氢化硅烷化生成甲硅烷基膦 (R1R2P-SiR3R4R5) 的第一个例子。此外，在涉及二级膦与氢硅烷的反应中引入 PhCN 允许杂脱氢偶联反应在更温和的条件下（1.0 mol% B(C6F5)3，25°C）有效进行。机理研究以及 DFT 计算表明，PhCN 在促进脱氢偶联反应中起着关键的机械作用，而不仅仅是作为 H2 受体。将 PhCN 引入涉及二级膦与氢硅烷的反应中，允许杂脱氢偶联反应在更温和的条件下（1.0 mol% B(C6F5)3，25°C）有效进行。机理研究以及 DFT 计算表明，PhCN 在促进脱氢偶联反应中起着关键的机械作用，而不仅仅是作为 H2 受体。将 PhCN 引入涉及二级膦与氢硅烷的反应中，允许杂脱氢偶联反应在更温和的条件下（1.0 mol% B(C6F5)3，25°C）有效进行。机理研究以及 DFT 计算表明，PhCN 在促进脱氢偶联反应中起着关键的机械作用，而不仅仅是作为 H2 受体。

更新日期：2017-11-14

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