"Sandwich" Diimine-Copper Catalysts for C-H Functionalization by Carbene Insertion.

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.