Visible‐Light‐Driven Deaminative Bromosulfonylation of Alkynes With Sulfonamides via a 10H‐Phenothiazine/Carbon Tetrabromide Electron Donor–Acceptor Complex

A visible‐light‐driven deaminative bromosulfonylation of alkynes using sulfonamides as the sulfonyl source is reported. The reaction employs unmodified 10H‐phenothiazine and CBr 4 , which form a halogen‐bonded EDA complex to initiate single‐electron transfer under blue LED at 40 °C. Terminal and internal alkynes are converted to ( E )‐β‐bromovinyl sulfones in good to excellent yields with exclusive stereoselectivity. The protocol tolerates functionalized sulfonamides, including drug derivatives, and is scalable to the gram scale. Mechanistic studies support a hybrid photo/thermal radical chain process.