Copper-Catalyzed Intermolecular [4 + 2] Annulation Enabled by Internal Oxidant-Promoted C(sp³)–H Functionalization: Access to 3‑Trifluoromethylated 3‑Hydroxy-cyclohexan-1-ones

A copper-catalyzed diastereoselective [4 + 2] cyclolization of α,β-unsaturated ketoxime acetates and trifluoromethyl ketones affords various 3-trifluoromethylated 3-hydroxy-cylcohexan-1-ones smoothly. This reaction features the selective functionalization of a less acidic C­(sp³)–H bond by an internal oxdative C­(sp³)–H functionalization strategy. Preliminary investigations revealed that α,β-unsaturated ketoxime acetates were an internal oxidant, and the in situ generated H₂O served as the O-source of the carbonyl oxygen in the product.