Synthetic Studies on the HIJK-Ring Fragment of Ciguatoxin

Synthesis of the tetracyclic HIJK-ring fragment of ciguatoxin with high stereoselectivity has been achieved starting from a sugar derivative directed toward the synthesis of the right part of ciguatoxin. Sonogashira coupling of a vinyl iodide with an acetylene derivative, cobalt complex-mediated (seven- and eight-membered ring) cyclizations and a heteroconjugate addition reaction play important roles in the current research work.