Practical route to the left wing of CTX1B and total syntheses of CTX1B and 54-deoxyCTX1B

Abstract

Ciguatoxins, the principal causative agents of ciguatera seafood poisoning, are extremely large polycyclic ethers. We report herein a reliable route for constructing the left wing of CTX1B, which possesses the acid/base/oxidant-sensitive bisallylic ether moiety, by a 6-exo radical cyclization/ring-closing metathesis strategy. This new route enabled us to achieve the second-generation total synthesis of CTX1B and the first synthesis of 54-deoxyCTX1B.

Keywords: ciguatoxin; polycyclic ether; radical reaction; ring-closing metathesis; total synthesis.