97(P-28) 高度に酸化されたトリテルペンポリエーテル(-)-エポキシトリTHFジオールと(+)-オーリロールの全合成と全立体構造の決定(ポスター発表の部)

抄録

Recently, highly oxidized and structurally unique triterpene polyethers, which are thought to be biogenetically squalene-derived natural products (oxasqualenoids), have been isolated from both marine and terrestrial lives. Among them are an epoxy tri-THF diol (1) isolated from the endemic Jamaican plant Spathelia glabrescens (Rutaceae) by Jacobs et al. in 2001 and aurilol (2) isolated from the sea hare Dolabella auricularia by Yamada et al. in 1998. Aurilol (2) exhibits cytotoxicity against HeLa S_3 cells with an IC_<50> of 4.3μg/mL. Many types of oxasqualenoids have been isolated; however, it is often difficult to determine their stereostructures only by spectroscopic analysis, especially in systems including acyclic quaternary carbon centers. In such cases, it is effective to predict and synthesize the possible stereoisomers. Although the plane structures and partial stereochemistries of 1 and 2 were also elucidated by NMR methods as shown in 1 and 2, determination of the entire stereochemistries of compounds 1 and 2 has not been reached. In this symposium, we report that the total assignment of the incomplete stereostructures of novel squalene-derived (-)-epoxy tri-THF diol (1) and (+)-aurilol (2) to the structural formulas 3 and 4, respectively, has been achieved through their first asymmetric total syntheses (Schemes 1-4).