Photoredox-Catalyzed Defluorinative [4 + 2] Cycloaddition of α-Fluoro-β-keto Esters and Alkynes by Single Photosensitizer

A protocol for C-F bond activation using a single organic photocatalyst was developed. The mechanism involves the self-sorting of α-fluorinated-β-keto esters to generate two radicals: one is highly electrophilic and undergoes rapid benzannulation with alkynes to form a series of 1-naphthols; the other is a tertiary carbon radical that serves as a HAT reagent to achieve substrate regeneration. Notably, the released F^- acts as an endogenous base in the reaction, obviating the need for external additives.