The first total synthesis of sespenine, a rare indole sesquiterpenoid from a mangrove endophyte, has been accomplished. A bioinspired aza-Prins/Friedel-Crafts/retro Friedel-Crafts cascade reaction assembles the bridged tetrahydroquinoline core. Further investigations on the aza-Prins cyclization imply that the C3 configuration of the hydroxyindolenine intermediate is crucial to the biosynthesis of sespenine and its congener xiamycin A.

A unified and bioinspired oxidative cyclization strategy was used in the first total syntheses of naturally occurring 12-epi-hapalindole Q isonitrile, hapalonamide H, deschloro 12-epi-fischerindole I nitrile, and deschloro 12-epi-fischerindole W nitrile, as well as the structural revision of the latter. Hapalindoles H and Q were also synthesized.

The first total synthesis of sespenine, a rare indole sesquiterpenoid from a mangrove endophyte, has been accomplished. A bioinspired aza‐Prins/Friedel–Crafts/retro Friedel–Crafts cascade reaction assembles the bridged tetrahydroquinoline core. Further investigations on the aza‐Prins cyclization imply that the C3 configuration of the hydroxyindolenine intermediate is crucial to the biosynthesis of sespenine and its congener xiamycin A.