Intramolecular photoreactions of thiohomophthalimides with an alkenyl group in their N‐Side chain. Regioselective synthesis of heterocycle‐fused isoquinoline derivatives through [2+2] photocycloaddition

Upon irradiation, thiohomophthalimides with an alkenyl group in their N‐side chain or at the benzylic position give tricyclic isoquinoline derivatives through regioselective intramolecular 2+2] cycloaddition or Norrish type II reaction, respectively, in good yields.