The engineering of molecular catalysts in homogeneous catalysis enables new catalytic modes, which leads to efficient synthetic transformations. In this regard, the design of ligands for transition metal catalysis has played a major role. In transition metal catalysed reactions, olefins can serve as steering ligands by tuning the electronic and steric nature of the metal centre. Here we report unstrained olefin ligands that bear a P or S coordination site for use in the Pd-catalysed Catellani reaction. This olefin ligand shows a covalent catalytic function and enables an efficient ipso,ortho-difunctionalization of iodoarenes. Mechanistic analysis reveals a reversible covalent bonding between the substrate and the cycloolefin unit of the ligand, which forms key organopalladium intermediates to enable a new reactivity. Our results demonstrate a design concept that employs hybrid cycloolefin ligands as a covalent catalytic module, which opens up possibilities for further cooperative catalysis with other transition metal–olefin hybrids.

均相催化中分子催化剂的工程设计使新的催化模式成为可能，从而导致有效的合成转化。在这方面，过渡金属催化配体的设计发挥了重要作用。在过渡金属催化的反应中，烯烃可以通过调节金属中心的电子和空间性质来充当转向配体。在这里，我们报告了带有 P 或 S 配位位点的无应变烯烃配体，用于 Pd 催化的 Catellani 反应。这种烯烃配体显示出共价催化功能，并能实现有效的ipso , ortho-碘芳烃的双官能化。机理分析表明，底物与配体的环烯烃单元之间存在可逆的共价键，从而形成关键的有机钯中间体，从而实现新的反应性。我们的结果证明了一种采用杂化环烯烃配体作为共价催化模块的设计概念，这为与其他过渡金属-烯烃杂化物进一步协同催化开辟了可能性。