Exploiting an intramolecular Diels–Alder cyclization/dehydro-aromatization sequence for the total syntheses of ellipticines and calothrixin B

The tetracyclic and pentacyclic skeletons of pyrido and quinolinocarbazole alkaloids have been synthesized via a unified strategy. The prominent key step involved a Diels-Alder intramolecular cyclization/dehydro-aromatization sequence. From these carbazole-lactam cores, linear syntheses have been developed for ellipticines and calothrixin B.