Synthetic studies of yessotoxin: Stereoselective annulation of the CD and JK ring fragments by using Pd(II)-catalyzed cyclization

Yessotoxin is the polycyclic ether implicated in diarrheic shellfish poisoning. This toxin has A-K ring system involving 6-, 7-, 8-membered ether rings. We have been studying high stereoselective Pd(II)-catalyzed cyclization. Herein we describe the CD and JK ring fragments of yessotoxin by our annulation based on Pd(II)-catalyzed cyclization. The efforts to understand these high stereoselectivities are also disclosed. This annulation method could be applicable to other polyethers and related natural products.