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A density functional theory study of the stereoselectivity of Cu(OTf)2‐catalyzed [3+2] cycloaddition of trifluoromethylated N‐acylhydrazones and isoprene: A concerted asynchronous mechanism
International Journal of Quantum Chemistry ( IF 2.2 ) Pub Date : 2020-04-08 , DOI: 10.1002/qua.26236
Jing Tang 1, 2 , Dong‐Hui Xu 1 , Xin Wang 1 , Laicai Li 1 , Xiang‐Yang Liu 1 , Xin‐Tong Su 3 , Jianmin Guo 2 , Bin Zhai 4
Affiliation  

Here we employ density functional theory calculations to systematically investigate the underlying mechanism of Cu(OTf)2‐catalyzed [3+2] cycloaddition reactions in the synthesis of CF3‐substituted pyrazolidines. About eight possible initial configurations of the [3+2] reaction is considered, and all relevant reactants, transition states, and products are optimized. Based on these structures, internal reaction coordinate paths, and wavefunction analysis results, we conclude that the Cu(OTf)2‐catalyzed [3+2] cycloaddition follows a concerted asynchronous mechanism. The CN bond forms immediately after the formation of the CC bond. Among the eight reaction paths, the energy barrier for the [3+2] reaction that leads to the CF3‐substituted syn ‐pyrazolidine is the lowest, ∼5.4 kcal/mol, which might result in the diastereoselectivity that is observed in the experiment. This work not only gives the detailed mechanism of the Cu(OTf)2‐catalyzed [3+2] cycloaddition but can also be helpful for the future designation of Cu(OTf)2‐based cycloaddition processes.

中文翻译:

密度泛函理论研究Cu(OTf)2催化的三氟甲基化N-酰基hydr和异戊二烯的[3 + 2]环加成反应的立体协同机理

在这里,我们采用密度泛函理论计算系统地研究了在CF 3取代的吡唑烷的合成中Cu(OTf)2催化的[3 + 2]环加成反应的潜在机理。考虑了[3 + 2]反应的大约八种可能的初始构型,并对所有相关的反应物,过渡态和产物进行了优化。基于这些结构,内部反应坐标路径和波函数分析结果,我们得出结论,Cu(OTf)2催化的[3 + 2]环加成反应遵循协调的异步机制。与c N键形成后,立即C的形成C键。在八种反应路径中,导致CF 3取代的顺式吡唑烷的[3 + 2]反应的能垒最低,约为5.4 kcal / mol,这可能导致实验中观察到的非对映选择性。这项工作不仅给出了Cu(OTf)2催化的[3 + 2]环加成反应的详细机理,而且还为将来基于Cu(OTf)2的环加成反应过程的设计提供了帮助。
更新日期:2020-04-08
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