Metal‐free photocyclization/oxidation cascade constructing quinoline‐2‐ones and tetrahydrocarbazolones

We reported a one‐pot photocyclization/ oxidation cascade of N ‐aryl acrylamides to afford quinoline‐2‐ones. Thioxanthone was used as a bifunctional energy transfer agent to mediate both photocyclization and generation of singlet oxygen, the latter facilitates the dehydrogenation of dihydroquinoline‐2‐one intermediate. This cascade strategy also supports the 5‐ endo ‐trig cyclization to synthesize tetrahydrocarbazolones from phenylamino cyclohexenones.