A short total synthesis of bioactive alkaloid calothrixin B have been accomplished with atom and step economy from commercially available starting materials. The key cyclization involved a Baylis−Hillman/6π electrocyclization/dehydroaromatiz‐ation sequence to construct the pentacyclic skeleton. Reduction of the resulting lactam followed by oxidation led to the characteristic quino[4,3‐b]carbazole framework. This intermediate underwent a direct oxidation with high regioselectivity to yield the final product.magnified image

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The tetracyclic and pentacyclic skeletons of pyrido and quinolinocarbazole alkaloids have been synthesized via a unified strategy.

An unexpected cascade reaction is developed for the construction of functionalized 3-bis(indol-3-yl)methylquinoline-2(1H)-ones. Three C–C bonds and one ring are created in one pot triggered by Pd-catalyzed C-3 alkenylation of indole with 2-acyl-N-acrylaniline derivatives. A series of complex and specific quinoline-2(1H)-ones were produced, most of them showed significant α-glucosidase inhibitory activities.