“Sandwich” Diimine‐Copper Catalysts for C−H Functionalization by Carbene Insertion

Abstract We report here “sandwich” diimine‐copper(I) catalysts for C(sp 3 )−H bond functionalization. Reactions of alkanes and ethers with trimethylsilyldiazomethane, ethyl diazoacetate, and trifluoromethyl‐diazomethane have been demonstrated. We also report C(sp 3 )−H bond methylation, benzylation, and diphenylmethylation by diazomethane, aryldiazomethanes, and diphenyldiazomethane. These reactions are rare examples of base‐metal catalyzed, intermolecular C(sp 3 )−H functionalizations by employing unactivated diazo compounds. Electrophilicity and unique steric environment of “sandwich”‐copper catalysts are likely reasons for their catalytic efficiency.