C–H bond sulfonylation of anilines with the insertion of sulfur dioxideundermetal-freeconditions is described. 2-Sulfonylanilines are generated in moderate to good yields through a three-component reaction of anilines, DABCO·(SO2)2, and aryldiazonium tetrafluoroborates under mild conditions. No metal catalysts or additives are needed for this transformation. This direct C–H functionalization is