Copper-Catalyzed Enantioselective Oxidation of Allylic C—H Bonds

Enantioselective allylic C-H oxidation represents an attractive strategy for the synthesis of chiral allylic oxygenated compounds.However, the development of catalytic asymmetric variants remains challenging due to the inherent inertness of C-H bonds and the difficulty in controlling stereoselectivity during C-H functionalization.A copper-catalyzed enantioselective allylic C-H oxidation, which allows the direct preparation of chiral allylic esters starting from simple alkenes, is reported.The reaction employs a chiral ligand-supported copper catalyst in combination with an N-Cl reagent to generate an N-centered radical capable of selective hydrogen atom transfer (HAT) to the allylic position of alkenes, forming an allylic radical intermediate.Subsequent capture of this radical by a copper-carboxylate species enables enantioselective C-O bond formation, affording the desired chiral allylic esters.The transformation proceeds under mild conditions and exhibits a broad substrate scope, accommodating both cyclic and acyclic alkenes with moderate to good yields and high levels of enantioselectivity.Notably, the reaction can be conducted with the alkene as the limiting reagent, addressing a common limitation of traditional allylic oxidation methods.