Synthesis of Natural Products with Polycyclic Systems

Herein we present our unique strategies to synthesize natural products. To prepare mersicarpine, an atypical indole alkaloid, our procedure features an Eschenmoser-Tanabe fragmentation to synthesize an alkyne unit, a combination of a Sonogashira coupling and a gold(III) catalyzed cyclization to construct the indole skeleton, and a one-pot process to arrange the cyclic imine and the hemiaminal moieties. Additionally, we synthesized a frog poison, histrionicotoxin, via a chirality transfer from an allenylsilane to prepare a pseudosymmetrical dienyne, dienyne metathesis to produce an optically active bicyclo [5.4.0] system, and an asymmetric propargylation. To synthesize lyconadin A, a Lycopodium alkaloid, a combination of an aza-Prins reaction and electrocyclic ring opening constructed the highly fused tetracyclic compound. The synthesis of isoschizogamine features a facile construction of the carbon framework through a Wagner-Meerwein rearrangement, a tandem metathesis, a stereoselective rhodium-mediated 1,4-addition of an arylboronic acid, and a ring-closing metathesis via a hemiaminal ether.