A rapid construction of a specific quino[4,3-b] carbazolone system and its application for the synthesis of calothrixin B

Abstract

An efficient methodology is developed for the synthesis of functionalized specific carbazole lactams related to pyrido[4,3-b]- and quino[4,3-b] carbazole alkaloids. 3 C–C bonds and 2 rings are created in a single step via an indole-to-carbazole transformation triggered by Pd(II)-catalyzed direct C-3 alkenylation of indoles. Starting from a key pentacyclic precursor delivered by the methodology, calothrixin B is synthesized in 6 steps.