分别从硅烷和二氢硅烷与水的反应中获得对称的硅氧烷和环四硅氧烷的选择性合成,并且该反应由NNN H t Bu钴(II)钳形配合物催化。有趣的是,当苯硅烷用水进行催化时,获得了由12个硅和18个氧中心组成的硅氧烷笼,反应明显进行,释放出3当量的分子氢(36 H 2)在温和的实验条件下。在硅烷与不同的硅烷醇反应后,通过钴催化实现了高选择性和受控的高级单氢硅氧烷和二甲氧基单氢硅烷的合成。释放的分子氢是在所有这些转化中观察到的唯一副产物。机理研究表明,反应是通过均质途径发生的。动力学和独立实验证实了硅烷催化氧化为硅烷醇的过程,并且进一步的脱氢偶联过程还涉及对称硅氧烷,环四硅氧烷和硅氧烷笼型化合物的合成,而硅烷和硅烷醇的不对称一氢硅氧烷则通过脱氢偶联反应进行合成。总体而言,这些钴催化的氧化偶联反应基于Si–H,Si–OH,和硅烷,硅烷醇和水的O–H键活化。建议使用由Co(II)中间体组成的催化循环。
开发了两种新的可回收硅基疏水标签,用于将它们安装在肽的 C 端,以增加在有机溶剂中的溶解度和液相肽合成 (LPPS) 过程中肽的反应性。它们包含含有甲硅烷氧基的标签和含有芳基甲硅烷基的标签。这些标签的疏水性比以前报道的例子要大得多。含有甲硅烷氧基的标签与Fmoc-脱保护条件(Fmoc-化学)和氢化条件(Cbz-化学)相容,而含有芳基甲硅烷基的标记对Fmoc-脱保护条件(Fmoc-化学)和Boc-脱保护条件具有抗性( Boc-化学)。使用含甲硅烷氧基的标签,受保护的 DRGN-1,采用线性合成结合一个收敛合成步骤成功制备了含有14个氨基酸残基的多肽。使用含有芳基甲硅烷基的标签,合成了含有 7 个丙氨酸残基的聚丙氨酸链。含有芳基甲硅烷基的标签也可以安装在 N 端,以将肽从 N 端延伸到 C 端。在这些硅基标签的帮助下,每一步的产率和产品在有机溶剂中的溶解度都非常好。
The arene-supported cationic nickel allylcomplexes serve as good catalysts for olefinhydrosilylation at room temperature. Detailed mechanistic studies based on experiments and DFT calculations support the novel mechanism, which...
SATURATED AND UNSATURATED SILAHYDROCARBONS VIA IRON AND COBALT PYRIDINE DIIMINE CATALYZED OLEFIN SILYLATION
申请人:Lewis Kenrick Martin
公开号:US20140330036A1
公开(公告)日:2014-11-06
The present invention relates to processes for the synthesis of saturated and unsaturated silahydrocarbons using iron-containing or cobalt-containing catalysts. The processes of the invention can produce tetraalkylsilanes, phenyltrialkylsilanes, substituted phenyltrialkylsilanes and their mixtures, which are useful as lubricants and hydraulic fluids, as well as alkyl alkenylsilanes, phenyl alkenylsilanes and substituted phenyl alkenylsilanes and their mixtures, which are useful in the synthesis of saturated silahydrocarbons and other organofunctional silanes.
of β-silyl α-amino acids is reported via the application of visible-light-mediated hydrosilylation. The reaction utilizes readily accessible and structurally diverse hydrosilanes to provide radicals for conjugate addition to dehydroalanine ester and analogues. Notably, the use of chiral methyleneoxazolidinone as the substrate and chiral inducer enabled the highly stereoselective synthesis. Furthermore
Regioselective Hydrosilylation of Olefins Catalyzed by a Molecular Calcium Hydride Cation
作者:Danny Schuhknecht、Thomas P. Spaniol、Laurent Maron、Jun Okuda
DOI:10.1002/anie.201909585
日期:2020.1.2
Chemo- and regioselectivity are often difficult to control during olefin hydrosilylation catalyzed by d- and f-block metal complexes. The cationichydride of calcium [CaH]+ stabilized by an NNNNmacrocycle was found to catalyze the regioselective hydrosilylation of aliphatic olefins to give anti-Markovnikov products, while aryl-substituted olefins were hydrosilyated with Markovnikov regioselectivity
Perfluoro cis-2,3-dialkyloxaziridine 2 is shown to perform the oxyfunctionalization of silanes 1 under very mild conditions to give silanols and silanediols 3 in high chemical yields and complete enantioselectivity.