Efficient Synthesis of Fused Polycyclic Ether Systems via Sulfonium Ylides: A Synthetic Approach to Yessotoxin and Adriatoxin.

A novel class of chiral sulfonium salts, derived from L- and D-methionine, was designed and successfully employed for the diastereoselective synthesis of epoxy amides. This new methodology of asymmetric epoxidation was exploited for the stereoselective construction of fused polycyclic ethers, which are structural motifs present in a great variety of natural products of marine origin. This methodology proved to be useful for the synthesis of the tricyclic A-C system contained in yessotoxin and adriatoxin, and also in many other related natural products of marine origin belonging to the fused polycyclic ether toxins.