Effective Strategy for the Preparation of Indolocarbazole Aglycons and Glycosides: Total Synthesis of Tjipanazoles B, D, E, and I

[reaction: see text] An effective strategy has been developed for the rapid and efficient preparation of ortho-nitrostyrenes, which can be converted to unsymmetrical 2,2'-biindoles. A unique condensation of these 2,2'-biindoles with (dimethylamino)-acetaldehyde diethyl acetal affords the indolocarbazole ring system of the tjipanazole aglycon alkaloids in three synthetic steps and good to excellent overall yield. The first total synthesis of the tjipanazole glycoside alkaloids B and E is also discussed.