17 海洋センブラノイドの化学 : 酸反応生成物の構造決定とエポキシド開裂反応の異常立体化学(口頭発表の部)

概要

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Sarcophytoxide (1) is a cembranoid isolated from soft coral, Sarcophyton glaucum. It is worth noting that this compound is contained in the organism in quite a large amount; 13g of crystalline 1 is deposited by keeping the hexane extract of the dry soft coral (240g) in a refrigerator overnight. Sarcophytoxide (1) has only weak biological activities. Its structure is characterized by an epoxide, a dihydrofuran, three olefin bonds, and a fourteen-membered ring. We intended to convert it chemically to compounds that have strong pharmaceutical activities. As the result, we succeed in the chemical transformation to an aromatic compound 12 that exhibits cytotoxic activity against A549 cell. 1 was treated with 0.5 equiv of TMSOTf or TfOH in benzene at room temperature for 20 minute. An aromatic compound 12 was obtained in 15% yield. The absolute configuration was determined by modified Mosher's method after a reduction to secondary alcohol 15. At the same time, we discovered unusual epoxide-ketone rearrangement. A ketone obtained as a major product by the rearrangement of sarcophytoxide is contradictory to that expected from the ordinary epoxide-ketone rearrangement. We suggest a new reaction mechanism of the epoxide-ketone rearrangement.
天然有機化合物討論会の論文
2006-09-15