Total Synthesis of Sarpagine Alkaloid (-)-Normacusine B.

An asymmetric total synthesis of the sarpagine alkaloid (-)-normacusine B is presented. Salient features of this synthesis include a photocatalytic nitrogen-centered radical cascade reaction to assemble the tetrahydrocarbolinone skeleton, a titanium-mediated intramolecular amide-alkene coupling to construct the bridged azabicyclo[3.3.1]nonane moiety, and a nickel-catalyzed reductive Heck coupling to assemble the azabicyclo[2.2.2]octane ring system.