Stereocontrolled synthesis of the IJK ring segment of yessotoxin

A stereocontrolled synthesis of the IJK ring segment of yessotoxin is described. Cyclization of 11 mediated by SmI2 gave the IJ ring system 12 as the sole product. Construction of the K ring moiety was performed by the acid catalyzed cyclization of epoxy alcohol 20 to afford the IJK ring segment in a highly stereocontrolled manner.