Csp³-Csp³ Bond-Forming Reductive Elimination from Well-Defined Copper(III) Complexes.

Area of Science:

• Organometallic Chemistry
• Catalysis
• Synthetic Chemistry

Background:

• Copper-catalyzed reactions are vital in organic synthesis.
• Organocopper(III) complexes are key intermediates but are rarely isolated.
• Formation of Csp3-Csp3 bonds via reductive elimination from these species is particularly challenging.

Purpose of the Study:

• To develop a general method for synthesizing stable organocopper(III) complexes.
• To investigate the reductive elimination of these complexes for Csp3-CF3 bond formation.
• To elucidate the mechanism of this reductive elimination process.

Main Methods:

• Synthesis of [alkyl-CuIII-(CF3)3]- complexes.
• Structural characterization using NMR spectroscopy, mass spectrometry, and X-ray crystallography.
• Kinetic studies and Density Functional Theory (DFT) calculations.

Main Results:

• A series of well-defined [alkyl-CuIII-(CF3)3]- complexes were successfully synthesized and characterized.
• These complexes undergo first-order reductive elimination at elevated temperatures, yielding alkyl-CF3 products in up to 91% yield.
• Kinetic and DFT studies revealed a concerted transition state for Csp3-CF3 bond formation with a barrier of 20 kcal/mol.

Conclusions:

• Stable organocopper(III) complexes can be synthesized and serve as effective precursors for Csp3-CF3 bond formation.
• The reductive elimination proceeds via a concerted mechanism, providing valuable insights into copper-catalyzed cross-coupling reactions.
• This work offers a new pathway for synthesizing trifluoromethylated compounds.