B(C6F5)(3)-Catalyzed Hydroboration of Alkenes with N-Heterocyclic Carbene Boranes via B-H Bond Activation
B(C6F5)(3)-Catalyzed Hydroboration of Alkenes with N-Heterocyclic Carbene Boranes via B-H Bond Activation
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B(C6F5)(3)-通过 B-H 键活化催化烯烃与 N-杂环卡宾硼烷的硼氢化反应
DOI：
10.1002/cjoc.202000489
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发表时间：
2021
影响因子：
5.4
通讯作者：
Du Haifeng
中科院分区：
文献类型：
--
作者：
Wang Qiaotian;Meng Wei;Feng Xiangqing;Du Haifeng
本文提出了一种新的活化N-杂环卡宾硼烷（NHC-硼烷）的方法，即通过刘易斯酸B（C6 F5）3以阻挫的刘易斯对方式夺取氢化物生成高活性的两性离子物种。包括均二苯乙烯、β-甲基苯乙烯、苯乙烯和烷基-烯烃的宽范围的烯烃是用于B（C6 F5）3-催化硼氢化的合适底物，以良好至高产率提供所需产物。值得注意的是，在某些情况下获得了优异的区域选择性。机理研究表明，B-H键断裂可能参与了速率决定步骤。此外，NHC-borenium阳离子的亲电加成烯烃和随后形成的碳正离子也被假定。目前的工作提供了一个很有前途的方法活化稳定的硼烷加合物，这可能会导致一些有趣的转变在未来。
In this work, a novel mode for the activation of N-heterocyclic carbene boranes (NHC-boranes) was developed by generating the highly reactive zwitterion species through hydride abstraction with Lewis acid B(C6F5)3 in an frustrated Lewis pairs manner. A broad range of alkenes including stilbenes, β-methylstyrenes, styrenes, and alkyl-alkenes were suitable substrates for the B(C6F5)3-catalyzed hydroboration to furnish the desired products in good to high yields. Significantly, excellent regioselectivities were obtained in some cases. Mechanistic studies indicate that the B—H bond cleavage is likely involved in the rate-determining step. In addition, an electrophilic addition of NHC-borenium cation to alkenes and the subsequent formation of carbocation are also postulated. The current work provides a promising method for the activation of stable borane adducts, which might lead to some interesting transformations in the future.