Total Synthesis of (-)-Mersicarpine

The total synthesis of (-)-mersicarpine was achieved in 10 steps from a known ketoester. Our synthesis features an Eschenmoser-Tanabe-type fragmentation to synthesize an alkyne unit containing a quaternary carbon center. a facile construction of the indole skeleton via a combination of a Sonogashira Coupling and a gold(Ill) catalyzed cyclization, as well as a one-pot process to arrange the cyclic imine and the hemiaminal moieties. Our synthesis unambiguously confirmed the reported structure of (-)-mersicarpine including the absolute configuration.