Total Syntheses of Anominine and Tubingensin A

A divergent strategy for the total syntheses of the indole
terpenoid
anominine (1) and its natural congener tubingensin A
(2) has been developed. The common intermediate 11 bearing all of the required stereogenic centers for both
natural products was first assembled by employing a Ueno–Stork
radical cyclization and a Sc­(OTf)3-mediated Mukaiyama aldol
reaction to form the key C–C bonds in a stereocontrolled manner.
The route to anominine features a radical deoxygenation followed by
an efficient side-chain installation, while the path to tubingensin
A exploits a CuOTf-promoted 6π-electrocyclization/aromatization
sequence to forge the central region of the pentacyclic scaffold.