立体选择性
化学
位阻效应
羧化
立体化学
密度泛函理论
计算化学
反应机理
催化作用
机制(生物学)
有机化学
哲学
认识论
作者
Abing Duan,Yali Yu,Fengqin Wang,Xue-Qiang Wang,Dongbo Wang
标识
DOI:10.1021/acs.joc.2c00161
摘要
Bromoalkynes play important roles in coupling reactions because they can show obvious stereoselectivity to form E- and Z-isomers when substituents are different. However, the origin of the stereoselectivity in the bromoalkynes reaction is still unclear. Density functional theory (DFT) calculations were performed to provide an in-depth study of the reaction mechanism, clarifying the mechanistic details of the main reaction and the origin of the stereoselectivity. By comparing the syn-insertion mechanism of alkynes and the radical pathway, it is indicated that the electrostatic effect caused by the different charge distributions of the reactants is the main reason that Ni(I) species are more prone to syn-insertion of alkynes than Ni(II) species. In addition, the lower reaction energy barrier in the radical pathway suggests that it is more advantageous in terms of kinetics. The bond between Ni(I) species and alkenylation products has two directions to generate products of different configurations, which are the direct stereoselectivity-determining stages. The distortion/interaction analysis shows that the distortion energy mainly affects the product configuration, and the steric hindrance is the main factor controlling the stereoselectivity.
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