Visible-Light-Promoted Radical Cascade Sulfone Alkylation/Cyclization of 2-Isocyanoaryl Thioethers Enabled by Electron Donor–Acceptor Complex Formation

A photo-induced cascade sulfone alkylation/cyclization of 2-isocyanoaryl thioethers is explored. This visible-light-triggered reaction not only occurs under extremely mild reaction conditions but also does not require the presence of a photosensitizer. The photocatalytic process is triggered by the photochemical activity of in situ-generated electron donor–acceptor complexes, arising from the association of 2-isocyanoaryl thioethers and α-iodosulfones. The radical pathway was confirmed by UV–vis spectroscopy, radical trapping, Job's plot, and on/off irradiation experiments.