Stereoselective 6-exo Radical Cyclization Using <i>cis</i>-Vinyl Sulfoxide: Practical Total Synthesis of CTX3C

Abstract

Ciguatoxins, the principal causative toxins of ciguatera seafood poisoning, are large ladder-like polycyclic ethers. We report a highly stereoselective 6-exo radical cyclization/ring-closing olefin metathesis sequence to construct the syn/trans-fused polyether system. The new method was applied to the practical synthesis of ciguatoxin CTX3C.