Copper-Catalyzed Reductive Alkylation of β-Acyl Allylic Thioethers with Alkyl Bromides to Access α-Branched Enones with Flexible Alkyl Chains.

Replacing alkyl organometallic reagents with alkyl bromides to achieve desulfurative alkylation of thioethers has been a long-standing challenge in desulfurative functionalization of organosulfur compounds. Herein, we report a copper-catalyzed reductive tertiary alkylation of β-acyl allylic sulfides with α-carbonyl alkyl bromides under mild reaction conditions. The reaction accommodates a broad substrate scope with good functional group compatibility, providing a direct route to install diversified (sp3)-carbon quaternary centers at the allylic position of α-branched enones. Further synthetic applications of this protocol have been demonstrated with scale-up experiments and late-stage modification of the products.