Photoredox- or Metal-Catalyzed in Situ SO2-Capture Reactions: Synthesis of β-Ketosulfones and Allylsulfones.

The first report of the in situ capture of the SO2 fragment of the trifluoromethylsulfonyl radical is described here. With cyclobutanone oximes as representative alkyl radical precursors, vinyl triflates and allyl trifluoromethylsulfones were employed as radical acceptors and SO2 sources to provide various β-ketosulfones and allylsulfones, known to be significant building blocks. Without the use of any additives including external SO2 gas, the reaction was performed under mild photoredox- or metal-catalytic conditions while tolerating various functional groups.