School of Chemistry, University of Manchester, Oxford Road, Manchester, UK M13 9PL.
Dalton Trans. 2011 Feb 7;40(5):1061-72. doi: 10.1039/c0dt01314e. Epub 2010 Dec 15.
The potential energy surfaces for ring-closing metathesis reactions of a series of simple α,ω-dienes which lead to 5-10 membered ring products, have been explored using density functional theory methods. We have investigated both the conformational aspects of the hydrocarbon chain during the course of the reactions, as well as the stationary structures on the corresponding potential energy surfaces. Extensive conformational searches reveal that the reaction proceeds via the conformation that would be expected for the cycloalkene product, though most unexpectedly, cyclohexene forms via complexes in boat-like conformations. The M06-L density functional has been used to map out the potential energy surfaces, and has identified metallocyclobutane fragmentation as being generally the highest barrier along the pathway. The structural variations along the pathway have been discussed for the reactant hydrocarbons of differing chain length to identify points at which cyclisation events may begin to affect reaction rates. Our study provides an excellent starting point from which to begin to learn about the way RCM reaction outcomes are controlled by diene structure.
使用密度泛函理论方法探索了一系列简单的α,ω-二烯的闭环复分解反应的势能面，这些二烯可以生成 5-10 元环产物。我们研究了反应过程中烃链的构象方面，以及相应势能面上的稳定结构。广泛的构象搜索表明，反应是通过预期的环烯烃产物的构象进行的，尽管最出乎意料的是，环己烯通过船形构象的配合物形成。M06-L 密度泛函被用于绘制势能面，并确定金属环丁烷的碎片化通常是沿反应途径的最高势垒。讨论了沿途径的结构变化，以确定不同链长的反应物烃中可能开始影响反应速率的环化事件的位置。我们的研究为开始了解 RCM 反应结果如何受二烯结构控制提供了一个很好的起点。
