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.

虽然涉及碳-碳双键的复分解反应，即烯烃复分解，已经在有机合成和材料科学中广泛应用，但动力学上不易接近的 C-C 单键的直接复分解极为罕见。在这里，我们报告了一种钌催化的可逆 C-C 单键复分解反应，该反应允许合成氧化还原和 pH 中性的联芳基。在定向基团的帮助下，无应变的同联芳基化合物经过芳基交换生成交叉联芳基产物，由明确定义的空气稳定的钌 (II) 配合物催化。在典型的交叉偶联反应下反应的官能团，例如卤素、甲硅烷基和硼酸酯部分，在复分解条件下是相容的。机理研究揭示了一种有趣的“类烯烃复分解”途径，该途径涉及一种意想不到的七配位、18 电子闭壳中间体。这里发现的独特反应模式有望激发更通用的 C-C 单键复分解和正交交叉偶联反应的发展。