Concise and flexible total syntheses of the pyrrolo [2, 3-c] carbazole alkaloids dictyodendrin B (2), C (3), and E (5) are described. These polycyclic telomerase inhibitors of marine origin derive from the common intermediate 18 which was prepared on a multigram scale by a sequence comprising a TosMIC cycloaddition with formation of the pyrrole A-ring, a titanium- induced reductive oxoamide coupling reaction to generate an adjacent indole nucleus, ...
