Sulfonylation of Anilines through Photocatalytic Activation of <i>N</i> -Hydroxymethylphthalimide Sulfones

Sulfones, sulfonamides, and sulfonyl fluorides are valuable motifs in drug discovery and organic chemistry, yet their synthesis often relies on prefunctionalized substrates or harsh oxidants, limiting their applicability in complex settings. The generation of sulfinyl radicals through photocatalytic means is one method to affect C–H sulfonylation chemistries. In this study, we have developed a N-hydroxymethylphthalimide (NHMP) sulfone functionality as a precursor to the sulfinyl radical after single-electron reduction. The utility of the NHMP sulfone is demonstrated through the sulfonylation of aniline substructures, including complex and biologically relevant scaffolds that were previously inaccessible. The NHMP group was joined with a sulfinate protecting group (SPG) to yield a bifunctional reagent capable of delivering additional sulfur(VI) functionalities, such as sulfonamides and sulfonyl fluorides. Mechanistic studies suggested a complex mechanism involving three possible mechanisms, including radical–radical coupling, electron donor–acceptor complexes, and nucleophilic chain pathways. Together, this work introduces a modular and operationally simple strategy for the synthesis of sulfur(VI)-containing small molecules, augmenting the overall toolbox available for the late-stage sulfonylation of complex molecules.