Modular Synthesis of Five-Membered Cyclic Sulfinamides via Photoexcited Radical [3+2] Cycloaddition of Arylidenecyclopropanes with N -Sulfinylamines

The efficient assembly of nitrogen- and sulfur-containing heterocycles remains a central objective in modern synthetic chemistry. Herein, we report a visible-light-mediated [3+2] cycloaddition between arylidenecyclopropanes and N -sulfinylamines, utilizing commercially available trimethylsilyl azide (TMSN 3 ) as a radical mediator. This transformation employs 4CzIPN as an organophotocatalyst at room temperature under metal- and oxidant-free conditions, providing a concise and atom-economical procedure for diverse five-membered cyclic sulfinamides in moderate to good yields with high selectivity, a broad substrate scope, and excellent functional group tolerance. Density functional theory (DFT) calculations revealed that the transformation proceeds via a sequential mechanism involving radical initiation, addition, ring opening, cyclization, and elimination.