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Updated: Aug 19, 2025

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双模双循环 [6 + 4] / [4 + 6] 过渡状态在循环二元化中与二极形途径竞争:热二元体的动态和实验性表征

Qingyang Zhou¹, Mathias K Thøgersen², Nomaan M Rezayee²

¹The College of Chemistry, Nankai University, Tianjin 300071, China.

Journal of the American Chemical Society

|November 28, 2022

概括

循环二聚化通过协同 [6 + 4] 或阶段性二基路径进行,形成四环产物. 温度影响主要的反应机制和产品分布.

科学领域:

有机化学
计算化学

背景情况:

环合是一种具有独特反应性的非类芳香化合物.
了解其热二元化对于预测反应途径和产品形成至关重要.

研究的目的:

阐明热环二聚化机制.
研究过渡状态和激进中间体的作用.
将计算预测与实验观察相关联.

主要方法:

使用 DFT 函数 (ωB97X-D,M06-2X) 和 HF 后方法 (DLPNO-CCSD,NEVPT2,PWPB95-D,BJ) 的量子力学研究.
准经典的分子动力学模拟.
试验分离和分离产品的表征.

主要成果:

预测了一种协同的 [6 + 4] 循环加法通过一个双模态的 [6 + 4]/ [4 + 6] 过渡状态和一个相竞争的阶段性二极性 (6 + 2) 循环加法.
与环二烯相比,确定了环二烯二元化中的高扭曲能量是相对较高的能量屏障的原因.
观察到温度依赖的产物形成:在较低的温度下呈现出 exo- [6 + 4]/ [4 + 6] 循环载荷管和在较高的温度下呈现出 diradical (6 + 2) 循环载荷管.

结论:

循环二烯的热二元化涉及复杂的双循环路径.
通过随后的分子内 [4 + 2] 循环添加,计算和实验数据证实了稳定的四环产品的形成.
温度是控制环合二元化选择性的关键因素.

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