Convergent synthesis of the HIJKLM ring fragment of ciguatoxin CTX3C

Abstract

Ciguatoxin CTX3C is a representative congener of the ciguatoxins, which are known to be the principal causative agents of ciguatera food poisoning. The structure of CTX3C spans more than 3 nm and is characterized by 13 ether rings. To attain a practical construction of this molecule, efficient supplies of the structural fragments are crucial. Herein we report the convergent synthesis of the HIJKLM ring fragment and present a new carbonyl olefination protocol to cyclize the J ring using low-valent titanium.