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 GaCl(3). The aryl carbenes react with PPh(3) 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.