Direct Observation of Aryl Gold(I) Carbenes that Undergo Cyclopropanation,C−H Insertion,and Dimerization Reactions

Mesityl gold(I) carbenes lacking heteroatom stabilization or shielding ancillary ligands have been generated and spectroscopically characterized from chloro(mesityl)methylgold(I) carbenoids bearing JohnPhos‐type ligands by chloride abstraction with GaCl₃. The aryl carbenes react with PPh₃ and alkenes to give stable phosphonium ylides and cyclopropanes, respectively. Oxidation with pyridine N‐oxide and intermolecular C?H insertion to cyclohexane have also been observed. In the absence of nucleophiles, a bimolecular reaction, similar to that observed for other metal carbenes, leads to a symmetrical alkene.