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. (Figure presented.). © 2020 Wiley-VCH GmbH