Catalytic AsymmetricTotal Syntheses of (−)-Galanthamineand (−)-Lycoramine

The catalytic asymmetric total syntheses of the biologically important and therapeutically valuable Amaryllidaceae alkaloids (−)-galanthamine and (−)-lycoramine have been divergently achieved from commercially available 3-butyn-1-ol. A newly developed spirocyclic pyrrolidine (SPD)-catalyzed enantioselective Robinson annulation rapidly constructs the key cis-hydrodibenzofuran core, which bears an all-carbon quaternary stereocenter of the target molecules with an excellent stereoselective control. Additionally, the current asymmetric synthetic strategy provides an alternative approach toward the syntheses of (−)-galanthamine and its analogues.