Overriding Nitrogen-Centered Reactivity of Sulfinamidyl Radicals Enables Sulfoximine Synthesis

The synthesis of sulfoximines under mild, modular conditions remains a challenge, reflecting broader limitations in controlling sulfur-centered radical reactivity. Here, we show that sulfinamides, previously associated primarily with nitrogen-centered radical pathways, can instead engage in productive sulfur-centered radical chemistry. This enables a photoredox strategy to access vinyl sulfoximines from readily prepared sulfinamides and vinyl bromides by diverting ambident sulfinamidyl radicals toward sulfur-centered C–S bond formation. Mechanistic experiments and DFT calculations support a pathway in which reversible sulfur addition is rendered productive by rapid subsequent β-scission of the halogen atom, thereby overriding thermodynamically favored nitrogen reactivity. The method provides broad access to diverse sulfoximines and tolerates varied vinyl halides, aryl and heteroaryl sulfinamides, and N-acyl substituents. In a representative enantioenriched example, excellent enantioretention is observed, consistent with an enantiospecific radical addition–elimination mechanism enabled by the configurational stability of the chiral sulfinamidyl radical, as supported by computed inversion barriers. These findings exemplify how rapid follow-on chemistry can override thermodynamic preference in reactions of ambident radicals.