69 シガトキシン部分構造の合成研究(ポスター発表の部)

概要

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Ciguatoxin (1) is a toxic principle of ciguatera, which is known as the most widespread food poisoning of dinoflagellate origin (Gambierdiscus toxicus). The toxin, consisting of 12 oxygen-containing fused rings, ranging six-to nine-membered, and a 5-membered spiro ether and 33 stereogenic centers, is one of the most potent neurotoxin and activates voltage dependent sodium channels. The very limited availability from natural sources has prevented further studies on pharmacological characteristics and development of highly specific immunoassay for the detection of the toxin. Our contribution was planned through chemical synthesis of a structural fragment of the toxin for the biological studies. In the present study, we report a stereoselective synthesis of the KLM ring fragment 36 of ciguatoxin (1.) from D-glucose derivative 11. A key feature of our synthesis is 7-endo selective cyclization of hydroxy epoxide for the construction of the K ring (29→30). The placement of 5-membered ring with trans junction leads to the selective formation of the bicyclic system containing an oxepane ring in the absence of an activator, such as an electron-rich double bond, for the selective cleavage of the epoxide.
天然有機化合物討論会の論文
1993-09-10