Total synthesis of indole alkaloid alsmaphorazine D.

A concise total synthesis of rac-alsmaphorazine D has been described for the first time. The efficient synthetic strategy features four key transformations: 1) a catalytic intramolecular oxidative cyclization for the δ-lactamindole backbone; 2) an oxidative cyclic aminal formation for the hexahydropyrrolo[2,3-b]pyrrole framework; 3) a transannular radical cyclization for the construction of the diazabicyclo[3.3.1]nonane structure; and 4) a one-pot desilylation/double epimerization reaction that affirms the relative stereochemistry.