Chiral Guanidine Catalyzed Annulation to the Core Structure of (‐)‐Huperzine A

Abstract

Abstract A bridged bicyclic compound (7), the key intermediate for the synthesis of (‐)‐huperzine A (1), was prepared by diastereoselective Michael‐aldol annulation of β‐keto ester (4) catalyzed by chiral guanidine (2). A variety of chiral catalysts, substrates and reaction conditions were tested.