Three‐Component Synthesis of β‐Ketosulfonamides via Visible‐Light‐Mediated Generation of Sulfamoyl Radicals

Abstract In this study, we report a photoredox‐catalyzed, visible‐light‐mediated three‐component synthesis of β‐ketosulfonamides from silyl enol ethers, N ‐aminopyridinium salts, and the sulfur dioxide (SO 2 ) surrogate DABSO (1,4‐diazabicyclo[2.2.2]octane·bis (sulfur dioxide) adduct). Eosin Y is used as readily available and cost‐efficient organic photoredox catalyst. This method is based on the photochemical generation of sulfamoyl radicals as key intermediates from N ‐aminopyridinium salts as nitrogen radical precursors and DABSO as an easy‐to‐handle, solid SO 2 source. Trapping of the in situ‐generated sulfamoyl radicals with silyl enol ethers affords pharmaceutically relevant β‐ketosulfonamides in 63%–91% yields.