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

Area of Science:

• Organometallic Chemistry
• Catalysis
• Organic Synthesis

Background:

• C(sp³)-H bond functionalization is crucial for organic synthesis.
• Developing efficient and selective methods using base metals remains a challenge.
• Diazo compounds are versatile reagents but often require precious metal catalysts.

Purpose of the Study:

• To develop novel "sandwich" diimine-copper(I) catalysts for C(sp³)-H bond functionalization.
• To demonstrate the use of unactivated diazo compounds in intermolecular C(sp³)-H functionalization reactions.
• To explore the scope of these reactions with various alkanes, ethers, and diazo reagents.

Main Methods:

• Synthesis and characterization of "sandwich" diimine-copper(I) complexes.
• Catalytic reactions involving alkanes/ethers and diazo compounds (e.g., trimethylsilyldiazomethane, ethyl diazoacetate).
• Analysis of reaction products to determine efficiency and selectivity.

Main Results:

• Demonstrated successful C(sp³)-H functionalization of alkanes and ethers using trimethylsilyldiazomethane, ethyl diazoacetate, and trifluoromethyl-diazomethane.
• Achieved C(sp³)-H bond methylation, benzylation, and diphenylmethylation using various diazo compounds.
• Established rare examples of base-metal catalyzed, intermolecular C(sp³)-H functionalizations with unactivated diazo compounds.

Conclusions:

• "Sandwich" diimine-copper(I) catalysts are effective for C(sp³)-H bond functionalization.
• The electrophilicity and steric properties of the catalysts contribute to their efficiency.
• These findings offer a new pathway for utilizing base metals in C-H activation chemistry.