Benallou Abdelilah, El Alaoui El Abdallaoui Habib, Garmes Hocine
Team of Chemoinformatics Research and Spectroscopy and Quantum Chemistry, Physical and Chemistry Lab, Faculty of Science, El Jadida, Morocco.
Laboratory of Bio-organic Chemistry, Department of Chemistry, Faculty of Science, El Jadida, Morocco.
Heliyon. 2018 Feb 6;4(2):e00504. doi: 10.1016/j.heliyon.2018.e00504. eCollection 2018 Feb.
The mechanism nature of the intramolecular Diels-Alder reaction has been performed; and thus, the changes of C-C bond forming/breaking along IRC are characterized in this study. Conceptual DFT analyses of the most favorable adduct fused/exo shows that the flux electronic will take place from diene to dienophile moiety. Moreover, ELF topological analysis based on the electron density predicts that C-C bond is formed by the coupling of two pseudoradical centers generated at the most significant atoms of the molecules. However, C2 vs C3, also C1 and C4 interaction comes mainly from the global electron density transfer which takes place along the reaction. Two- stage one-step is the proposed mechanism of this reaction, the first stage aims for the formation of C2-C3 σ bond while the second stage aims for C1-C4 σ bond formation. Interestingly, the observed asynchronicity of this IMDA reaction due principally to the asymmetric reorganization of electron density at the most attractive centers.
分子内狄尔斯-阿尔德反应的机理本质已得到研究；因此，本研究对沿反应路径的碳-碳键形成/断裂变化进行了表征。对最有利的加合物稠合/外向型进行的概念性密度泛函理论分析表明，电子通量将从双烯体部分转移到亲双烯体部分。此外，基于电子密度的电子定域函数拓扑分析预测，碳-碳键是由分子中最重要原子处产生的两个准自由基中心耦合形成的。然而，C2与C3以及C1和C4之间的相互作用主要来自沿反应发生的整体电子密度转移。两步一步法是该反应提出的机理，第一阶段旨在形成C2-C3 σ键，而第二阶段旨在形成C1-C4 σ键。有趣的是，观察到的这种分子内狄尔斯-阿尔德反应的异步性主要归因于最具吸引力中心处电子密度的不对称重新排列。
