48 海産細胞毒スチポルジオンの合成研究(口頭発表の部)

概要

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Synthetic studies on stypoldione [1], a cytotoxic and ichthyotoxic metabolite of the marine alga, Stypopodium zonale, are described. One of the key steps in the synthetic schemes is the construction of the spirocyclic unit. So we decided to study the intramolecular Michael reaction as a model experiment. The (±)-bicyclic ketoester [3] was converted to the enone [11] in 14 steps. The intramolecular Michael reaction was accomplished by treatment of [11] with BBr_3 to give the desired spirobenzofuran [12] stereoselectively, which was converted to (±)-14-deoxystypoldione [14]. As a next stage, we attempted to synthesize optically active stypoldione [1]. (S)-Hydroxyketone [E] readily available by reducing the 1,3-diketone [F] with baker's yeast was employed as a chiral starting material. It was converted to the β-ketoester [22], which gave tricyclic ketoester [23], via Lewis acid-promoted cyclization. Transformation of [23] into (-)-stypoldione [1] is now under investigation.
天然有機化合物討論会の論文
1990-09-25