用硼烷和硼正离子对三甲基硅基取代的炔烃和丙二烯进行碳硼化反应。
The carboboration of Me3Si-substituted alkynes and allenes with boranes and borocations.
作者信息
Lawson James R, Fasano Valerio, Cid Jessica, Vitorica-Yrezabal Inigo, Ingleson Michael J
机构信息
School of Chemistry, University of Manchester, Manchester, M13 9PL, UK.
出版信息
Dalton Trans. 2016 Apr 14;45(14):6060-70. doi: 10.1039/c5dt03003j. Epub 2015 Sep 16.
The 1,1-carboboration of 1-Me3Si-1-alkynes is the dominant reaction observed using [PhBCl(2-DMAP)][AlCl4], 1, and PhBCl2 electrophiles, with highly substituted vinyl pinacol boronate esters isolated post esterification. Other aryl and heteroaryl congeners of both 1 and PhBCl2 have a limited scope in the 1,1-carboboration of 1-Me3Si-1-alkynes, with desilylboration more prevalent. PhBCl2 converts Me3Si-substituted allenes to allylboranes via a formal 1,3-carboboration with Me3Si-migration. [Cl2B(2-DMAP)][AlCl4] reacts with a number of 1-Me3Si-1-alkynes by desilylboration, whilst with Me3Si-ethyne a 1,1-boroamination reaction proceeds, which with excess boron electrophile is followed by an intermolecular desilylboration to form a tricationic-borate. The use of excess 1-Me3Si-1-propyne relative to 1 (and a thienyl congener of 1) formed 2-boradienes in low yields from the reaction with two equivalents of alkyne. Vinyl borocations ligated by 2,6-lutidine of the general formula, [(vinyl)BCl(2,6-lutidine)][AlCl4] formed 1-boradienes with 1-Me3Si-1-alkynes.
使用[PhBCl(2 - DMAP)][AlCl₄]（1）和PhBCl₂亲电试剂时，1 - Me₃Si - 1 - 炔烃的1,1 - 碳硼化反应是主要观察到的反应，酯化后可分离得到高度取代的乙烯基频哪醇硼酸酯。1和PhBCl₂的其他芳基和杂芳基类似物在1 - Me₃Si - 1 - 炔烃的1,1 - 碳硼化反应中的适用范围有限，脱硅硼化反应更为普遍。PhBCl₂通过与Me₃Si迁移的形式1,3 - 碳硼化反应将Me₃Si取代的丙二烯转化为烯丙基硼烷。[Cl₂B(2 - DMAP)][AlCl₄]通过脱硅硼化反应与多种1 - Me₃Si - 1 - 炔烃反应，而与Me₃Si - 乙炔则发生1,1 - 硼胺化反应，在过量硼亲电试剂存在下，随后发生分子间脱硅硼化反应形成三阳离子硼酸酯。相对于1（以及1的噻吩基类似物）使用过量的1 - Me₃Si - 1 - 丙炔，与两当量的炔烃反应以低产率生成2 - 硼二烯。通式为[(乙烯基)BCl(2,6 - 二甲基吡啶)][AlCl₄]的由2,6 - 二甲基吡啶配位的乙烯基硼正离子与1 - Me₃Si - 1 - 炔烃形成1 - 硼二烯。
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