Photocatalyst-free formate-mediated C-O cleavage by the EDA complex and SCS strategy for the synthesis of diaryl 1,4-diketone in air.

Under mild visible light conditions, formates facilitate C-O cleavage via the EDA complex and SCS strategy, yielding α-carbonyl alkyl radicals. These radicals then react with olefins under air conditions, leading to the synthesis of diaryl 1,4-dicarbonyl compounds. Mechanistic studies reveal that α-formyloxy ketone is generated in situ by the reaction between α-brominated acetophenone and formates, followed by the formation of the EDA complex. Additionally, formates also serve as a single-electron reducing reagent in the reaction.