Photosensitized [4+2]‐ and [2+2]‐Cycloaddition Reactions of <i>N</i>‐Sulfonylimines

Abstract The synthesis of polycyclic compounds is high interest due to the prevalence these motifs in drugs and natural products. Herein, we report on stereoselective construction 3D bicyclic scaffolds azetidine derivatives by modulation N ‐sulfonylimines achieve either [4+2]‐ or [2+2]‐cycloaddition reactions. utility method was established further product. Mechanistic studies are also included, which support reaction via Dexter energy transfer.