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.