研究了三氯乙酸钠与各种有机硅氢化物在1,2-二甲氧基乙烷中的反应,形成了α-三有机甲硅烷基二氯甲烷,产率为20%至50%。通过竞争反应确定在这些二氯卡宾的插入反应中这些氢硅烷的相对速率常数。一系列烷基取代的氢硅烷的相对反应性与硅上取代基的Taftσ*常数高度相关,ϱ *值为-1.07,一系列芳基取代的氢硅烷也显示出log k rel良好的线性相关性值具有Taftσ*常数,giving *值为-1.18。反应中的氢同位素效应k H / k D1.26±0.02。基于观察到的结果,可以得出结论,Cy 2插入SiH键中是通过三中心协同过程进行的,该过程中过渡态的电荷分离不大,正如塞弗特(Seyferth)对相关的PhHgCCl 2提出的那样。 Br / XC 6 H 4 SiMe 2 H反应。
Synthesis of Silicon-Stereogenic Silanols Involving Iridium-Catalyzed Enantioselective C–H Silylation Leading to a New Ligand Scaffold
作者:Hongpeng Zhang、Dongbing Zhao
DOI:10.1021/acscatal.1c03112
日期:2021.9.3
organosilicon compounds, the enantioselective synthesis of silicon-stereogenic silanols through asymmetric catalysis remains a considerable challenge. Herein, we realized enantioselective construction of silicon-stereogenic diarylsilanols via an Ir-catalyzed C–H silylation of diarylsilanols along with stereospecific substitution or Tamao–Fleming oxidation. This strategy gives rise to a class of chiral diol catalyst
尽管人们越来越关注高度对映体富集的硅-立体异构有机硅化合物的构建,但通过不对称催化对硅-立体异构硅烷醇的对映选择性合成仍然是一个相当大的挑战。在此,我们通过 Ir 催化的二芳基硅烷醇的 C-H 甲硅烷基化以及立体有择取代或 Tamao-Fleming 氧化实现了硅-立体异构二芳基硅烷醇的对映选择性构建。这种策略产生了一类手性二醇催化剂核 (psiols)。psiol 的转化导致配体同时具有 Si 和 P 立体中心,这能够在铑 (I) 催化的芳基硼酸与环己烯酮的共轭 1,4-加成中产生出色的对映选择性。
Yttrium-Catalyzed Regioselective α-C–H Silylation of Methyl Sulfides with Hydrosilanes
The catalytic C–H silylation of sulfides with hydrosilanes is of much interest and importance but has remained unexplored to date. We report here the C–H silylation of methylsulfides with hydrosilanes by an yttrium metallocene catalyst. The reaction took place regioselectively at the α-methyl C–H bond, affording the corresponding silylated sulfide derivatives that are difficult to make by other means
B(C
<sub>6</sub>
F
<sub>5</sub>
)
<sub>3</sub>
/Amine‐Catalyzed C(sp)−H Silylation of Terminal Alkynes with Hydrosilanes: Experimental and Theoretical Studies
C(sp)−H silylation of a wide range of terminalalkynes with hydrosilanes by using a combination of B(C6F5)3 and an organic base such as triethylenediamine (DABCO). This protocol constitutes the first example of boron‐catalyzed C(sp)−H functionalization, offering a convenient route for the synthesis of a variety of alkynylsilanes. Experimental and computational studies have revealed that DABCO plays two
过渡金属催化的有机化合物的CH官能化已被证明是有机合成中有用的原子效率策略。相比之下,迄今为止,对于CHH功能化的基于主族元素的催化过程仍未得到充分研究。本文报道的是通过使用B(C 6 F 5)3的组合,各种末端炔烃与氢硅烷的催化C(sp)-H甲硅烷基化反应和有机碱,例如三乙二胺(DABCO)。该协议构成了硼催化的C(sp)-H功能化的第一个例子,为合成各种炔基硅烷提供了一条便捷的途径。实验和计算研究表明,DABCO在此催化转化中起着两个至关重要的作用(刘易斯碱和布朗斯台德碱)。
Réactions non classiques au cours de l'alkylation de dérivés d'éléments de la colonne IVB par des réactifs de Grignard
The reduction of derivatives of the type RnSiσ4-n (σ = Cl, OCH3) by some organomagnesium compounds RMgX at high temperature (⩾80°) leads to the hydrosilanes RR'SiH2 and RR'2SiH in various ratios according to the considered reagents. The results described in this publication constitute a first approach in the knowledge of the mechanism of these reductions. A deeper study of the mechanism is the subject