美国芝加哥大学董广斌团队的一项最新研究提出了通过非张力C(芳基)–C(芳基)单键的分子间复分解反应实现正交交叉偶联。相关论文于2021年8月2日发表在《自然—化学》杂志上。

该研究团队报告了一个钌催化的可逆C-C单键复分解反应，允许氧化还原和pH中性联芳基合成。在导向基团的辅助下，非应变的同型联芳基化合物在空气稳定的钌(II)配合物的催化下进行芳基交换，生成交叉联芳基产物。

在典型的交叉偶联反应下反应的官能团，如卤素、硅基和硼酸基团，在复分解条件下是相容的。机理研究揭示了一个有趣的“烯烃易位”途径，涉及一个意想不到的七配位、18电子封闭壳层中间体。本研究发现的独特的反应模式，有望启发更普遍的C-C单键复分解和正交交叉偶联反应的发展。

据介绍，虽然涉及碳-碳双键的复分解反应，即烯烃复分解，在有机合成和材料科学中已经建立了广泛的应用，但在动力学上难以接近的碳-碳单键的直接复分解是极其罕见的。

附：英文原文

Title: Orthogonal cross-coupling through intermolecular metathesis of unstrained C(aryl)–C(aryl) single bonds

Author: Zhu, Jun, Zhang, Rui, Dong, Guangbin

Issue&Volume: 2021-08-02

Abstract: While metathesis reactions involving carbon–carbon double bonds, namely olefin metathesis, have been well established with broad utility in organic synthesis and materials science, direct metathesis of kinetically less accessible C–C single bonds is extremely rare. Here we report a ruthenium-catalysed reversible C–C single-bond metathesis reaction that allows redox- and pH-neutral biaryl synthesis. Assisted by directing groups, unstrained homo-biaryl compounds undergo aryl exchanges to generate cross-biaryl products, catalysed by a well-defined air-stable ruthenium(II) complex. Functional groups reactive under typical cross-coupling reactions, such as halogen, silyl and boronate moieties, are compatible under the metathesis conditions. Mechanistic studies disclose an intriguing ‘olefin-metathesis-like’ pathway that involves an unexpected heptacoordinated, 18-electron closed-shell intermediate. The distinct reaction mode discovered here is expected to inspire the development of more general C–C single-bond metathesis and orthogonal cross-coupling reactions.

DOI: 10.1038/s41557-021-00757-4

Source: https://www.nature.com/articles/s41557-021-00757-4