A base-controlled switch of SO2 reincorporation in photocatalyzed radical difunctionalization of alkenes

Control of selectivity is a pivotal challenge in radical chemistry owing to the high reactivity and instability of radical species. Herein, a switchable, base-controlled strategy toward the reincorporation/release of SO2 in photocatalyzed radical difunctionalization of alkenes has been described. By this chemodivergent strategy, a variety of valuable, otherwise difficult-to-access γ-trifluoromethylated ketones and trifluoromethylated sulfonyl ketones can be selectively furnished from the same starting materials. This method features high chemoselectivity, a broad substrate scope, excellent functional group tolerance, and facile scale-up and was applied in a one-pot synthetic procedure. Evaluation of the reaction conditions and mechanistic studies indicate that the choice of base can invert the chemoselectivity of the reaction, demonstrating control over a challenging radical selectivity pattern.