Mes‐Acr ⁺ BF ₄ ⁻ Catalyzed Visible‐Light Aerobic Synthesis of α ‐ketoa

ABSTRACT

A metal‐free and environmentally benign photocatalytic strategy has been developed for the construction of α‐ketoamides from readily accessible β ‐keto acids and amines under visible‐light irradiation. Using the organic photoredox catalyst Mes‐Acr ⁺ BF ₄ ⁻ (9‐mesityl‐10‐methylacridinium tetrafluoroborate), this protocol eliminates the need for hazardous stoichiometric oxidants and iodine‐based reagents. The transformation proceeds through a photoinduced electron‐transfer pathway, generating radical intermediates that undergo oxygen‐dependent oxidation followed by amine incorporation and selective C–C bond cleavage. This cascade sequence furnishes a diverse range of α ‐ketoamide derivatives in moderate to good yields under mild, operationally simple, and scalable conditions. The method offers a sustainable and mechanistically well‐defined approach to valuable 1,2‐dicarbonyl scaffolds relevant to complex‐molecule synthesis and late‐stage functionalization.