废止
叶立德
化学
区域选择性
立体选择性
反应性(心理学)
催化作用
亲核细胞
立体化学
脱质子化
药物化学
对映选择合成
有机化学
医学
离子
替代医学
病理
作者
Yan Li,Junjie Xiao,Yanlong Kang,Zhiqiang Zhang
标识
DOI:10.1016/j.mcat.2024.114146
摘要
The catalytic mechanism for dearomatizing annulation of ester with ylide by a chiral NHC catalyst is investigated by density functional theory (M06–2X) computations. After precatalyst activation giving active NHC, the transformation proceeds via five steps: (1) nucleophilic addition of the NHC to ester, (2) α−CH deprotonation to generate acylazolium intermediate, (3) coupling acylazolium intermediate with ylide to form a new C − C bond, (4) ring closure and (5) elimination of the NHC with formation of the annulation product tricyclic dihydroisoquinoline. The regio- and stereoselectivity controlling step is C − C bond formation. For regioselectivity, local reactivity index analysis indicates that the C1-addition is more favorable than either C3 or C4 addition. The stereoselectivity for the formation of SS-configurational product is ascribed to a number of noncovalent interactions (C–H·O, C–H·N and C–H·π). Electron localization function (ELF) analyses reveal the important role of the NHC in Ccarbonyl−Ocarbonyl bond breaking. These results enable both in-depth understanding of NHC catalysis and rational design of catalytic reactions.
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