Wang Zheng, Zhou Yu, Lee Ka-Ho, Lam Wai Han, Dewhurst Rian D, Braunschweig Holger, Marder Todd B, Lin Zhenyang
Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong.
Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Chemistry. 2017 Aug 25;23(48):11587-11597. doi: 10.1002/chem.201701737. Epub 2017 Aug 3.
Boroles undergo dimerization reactions to give Diels-Alder (DA) dimers, bridged-bicyclic (BB) dimers or spiro dimers (SD) depending on the substituents on the borole. We performed DFT calculations to investigate how different substituents at the carbon atoms of the butadiene backbone as well as at the boron atom influence the dimerization reaction pathways. The DFT results show that, in general, both the DA and BB dimers are easily accessible kinetically, and the DA dimers are thermodynamically more stable than the BB dimers. When the substituent-substituent repulsive steric interactions are alleviated to a certain extent, the BB dimers are more stable than the DA dimer, and become accessible. The SD dimers are generally kinetically difficult to obtain. However, we found that aryl substituents promote the formation of the SD dimers.
硼杂环丁二烯会发生二聚反应，根据硼杂环丁二烯上的取代基不同，生成狄尔斯-阿尔德（DA）二聚体、桥连双环（BB）二聚体或螺二聚体（SD）。我们进行了密度泛函理论（DFT）计算，以研究丁二烯主链碳原子以及硼原子上的不同取代基如何影响二聚反应途径。DFT结果表明，一般来说，DA二聚体和BB二聚体在动力学上都易于生成，并且DA二聚体在热力学上比BB二聚体更稳定。当取代基-取代基之间的排斥性空间相互作用在一定程度上得到缓解时，BB二聚体比DA二聚体更稳定，并且易于生成。SD二聚体通常在动力学上难以得到。然而，我们发现芳基取代基会促进SD二聚体的形成。
