Csp^3-Csp^3 Bond-Forming Reductive Elimination from Well-Defined Copper(III) Complexes

Abstract

Carbon–carbon bond-forming reductive elimination from elusive organocopper(III) complexes has been considered the key step in many copper-catalyzed and organocuprate reactions. However, organocopper(III) complexes with well-defined structures that can undergo reductive elimination are extremely rare, especially for the formation of Csp^3–Csp^3 bonds. We report herein a general method for the synthesis of a series of [alkyl-Cu^(III)-(CF_3)_3]^− complexes, the structures of which have been unequivocally characterized by NMR spectroscopy, mass spectrometry, and X-ray crystal diffraction. At elevated temperature, these complexes undergo reductive elimination following first-order kinetics, forming alkyl-CF3 products with good yields (up to 91%). Both kinetic studies and DFT calculations indicate that the reductive elimination to form Csp^3–CF^3 bonds proceeds through a concerted transition state, with a ΔH⧧ = 20 kcal/mol barrier.