Photoredox-Catalyzed N-Centered Radical-Mediated Cascade Annulation/Dearomatization of ortho -Sulfonamide-Tethered Alkylidenecyclopropanes

A photochemical strategy enabling tandem cyclization and dearomatization of ortho-sulfonamide-tethered alkylidenecyclopropanes via N-centered radicals has been developed under metal-free conditions. The reaction employs an organic fluorophore 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as a photocatalyst. This mild and operationally simple photocatalytic system demonstrates that the sulfonamidyl-radical-mediated intramolecular olefin amination effectively integrates radical ring opening with dearomatization pathways, thereby facilitating the synthesis of diverse fused seven-membered cyclic sulfonamides with a broad substrate scope, high regioselectivity, and excellent product diversity.