Synthesis of Lycopodium Alkaloids

Our syntheses of fawcettimine-type Lycopodium alkaloids, hupezine Q, lycoposerramine-S and lycopalhine A are described. Huperzine Q was synthesized via a Diels-Alder reaction and a ring contraction reaction of an epoxyketone into a cyclopentanone. The synthesis of lycoposerramine-S features an intramolecular cycloaddition of azomethine ylide. The core structure of lycopalhine A was constructed by means of cleavage of a cyclopropane ring and intramolecular Michael addition of a sulfonamide moiety to an enone. Stereoselective introduction of the units to the core structure and formation of the ring systems led to the total synthesis of lycopalhine A.