Enantioselective Formal α-Methylation and α-Benzylation of Aldehydes by Means of Photo-organocatalysis

Detailed herein is the photochemical organocatalytic enantioselective alpha-alkylation of aldehydes with (phenylsulfonyl) alkyl iodides. The chemistry relies on the direct photoexcitation of enamines to trigger the formation of reactive carbon-centered radicals from iodosulfones, while the ground-state chiral enamines provide effective stereochemical control over the radical trapping process. The phenylsulfonyl moiety, acting as a redox auxiliary group, facilitates the generation of radicals. In addition, it can eventually be removed under mild reducing conditions to reveal methyl and benzyl groups.