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 [alkyl-Cu III-(CF 3) 3 ]complexes, the structures of which have been unequivocally characterized by NMR, mass spectrometry and X-ray crystal diffraction. At elevated temperature, these complexes undergo reductive elimination following first-order kinetics, forming alky-CF 3 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.

Trifluoromethyl-containing compounds play a significant role in medicinal chemistry, materials and fine chemistry. Although direct C-H trifluoromethylation has been achieved on Csp -H bonds, direct conversion of Csp -H bonds to Csp -CF remains challenging. We report herein an efficient protocol for the selective trifluoromethylation of benzylic C-H bonds. This process is mediated by a combination Cu -CF species and persulfate salts. A wide range of methylarenes can be selectively trifluoromethylated at the benzylic positions. A combination of experimental and theoretical mechanistic studies suggests that the reaction involves a radical intermediate and a Cu -CF species as the CF transfer reagent.

We report herein a highly efficient Cucatalyzed protocol for the conversion of aliphatic carboxylic acids to the corresponding difluoromethylated analogues. This robust, operationally simple and scalable protocol tolerates a variety of functional groups and can convert a diverse array of acid-containing complex molecules to the alkyl-CF 2 H products. Mechanistic studies support the involvement of alkyl radicals.

We report herein the first catalytic strategy to harness amidyl radicals derived from N-chloroamides for C–C bond formation, allowing for the discovery of the first catalytic benzylic C–H difluoromethylation. Under copper-catalyzed conditions, a wide variety of N-chlorocarboxamides and N-chlorocarbamates direct selective benzylic C–H difluoromethylation with a nucleophilic difluoromethyl source at room temperature. This scalable protocol exhibits a broad substrate scope and functional group tolerance, enabling late-stage difluoromethylation of bioactive molecules. This copper-catalyzed, chloroamide-directed strategy has also been extended to benzylic C–H pentafluoroethylation and trifluoromethylation. Mechanistic studies on the difluoromethylation reactions support that the reactions involve the formation of benzylic radicals via intramolecular C–H activation, followed by the copper-mediated transfer of difluoromethyl groups to the benzylic radicals.

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