Three-component synthesis of beta-ketosulfonamides via visible-light mediated generation of sulfamoyl radicals

Herein, we report photoredox-catalyzed, visible-light mediated 3-component synthesis of beta-ketosulfonamides from silyl enol ethers, N-aminopyridinium salts and the sulfur dioxide (SO2) surrogate DABSO (1,4-diazabicyclo[2.2.2]octane·bis (sulfur dioxide) adduct). This reaction is based on the photochemical generation of sulfamoyl radicals from N-aminopyridinium salts as nitrogen radical precursors and DABSO as easy-to-handle SO2 source. Trapping of the in situ generated sulfamoyl radicals with silyl enol ethers affords beta-ketosulfonamides in 63-97% yield in the presence of Eosin Y as organic photoredox catalyst.