1999 年 47 巻 11 号 p. 1626-1628
The crystal structure of polyporusterone A, from Polyporus umbellatus F. was determined by X-ray diffraction analysis. The crystals are orthorhombic, space group P212121, Z=4, unit-cell dimension a=17.968(2), b=26.201(5), c=6.227(1) Å. The structure, (+)-2β, 3β, 14α, (20R, 22R)-pentahydroxy-(24S)-methyl-5β-cholest-7-en-6-one, was solved from diffractometric data by direct methods and refined by least-squares calculations to R=0.053 (2345 observed independent significant reflections (I>3σ(I)). All the hydroxyl groups are involved in a hydrogen-bonding network. The NMR data indicate that the side-chain has the same conformation in both the crystalline state and solution.