Construction of Hexahydropyrido[3,2‐ c ]carbazole and Hexahydropyrrolo[3,2‐ c ]carbazole Skeletons for the Synthesis of Related Indole Alkaloids

Synthesis of tetracyclic hexahydropyrido[3,2‐ c ]carbazoles ( 9a and 9b ) and hexahydropyrrolo[3,2‐ c ]carbazoles ( 13a and 13b ) structures was achieved via a new synthetic approach for the synthesis of related indole alkaloids such as deethylaspidospermidine and deethylibophyllidine. Hexahydropyrrolo[3,2‐ c ]carbazole structure was constructed for the first time starting from ethyl 4‐oxo‐cyclohexanecarboxylate in seven steps. Some tetrahydrocarbazole derivatives ( 4 , 5 , 6 , 7 , 11 , and 12 ) were also synthesized.