Abstrak 
(20S)-Dammar-24-ene-3β,20-diol mono-hydrate from the bark of Aglaia exima (Meliaceae)
Agus Safariari, Asep Supriadin, Unang Supratman, Khalijah Awang, Seik Weng Ng
Universitas Padjadjaran, Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368
Bahasa Inggris
Universitas Padjadjaran, Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368
data-to-parameter ratio = 44.4., disorder in main residue, R factor = 0.077, single-crystal X-ray study, T = 100 K; mean a(C—C) = 0.003 A, wR factor = 0.266
In the title compound (systematic name: (1R,2R,5R,7RJOR,- 11R,14S,15R)-14-[(2S)-2-hydroxy-6-methylhept-5-en-2-y1]-2,6,6,10,11-pentamethyltetracyclo[8.7.0.02.7.011.15]heptadecan-5-ol monohydrate), C30H5202-H20, the three fused cyclo¬hexane rings adopt chair conformations and the hydroxy substituent of one of these occupies an axial position. The fused cyclopentane ring adopts an envelope conformation (with the flap atom being the C atom bearing the methyl group) and the 3-methylbut-2-enyl portion of its substituent is disordered over three sets of sites in a 0.413 (7):0.250 (7):0.337 (7) ratio. The 0 atoms of both water molecules occupy special positions of 2 site symmetry. In the crystal, Os—H—Ow and Ow—H—Os (s = steroid and w = water) hydrogen bonds link hydroxy groups and water molecules, forming a three-dimensional network. The crystal studied was found to be a non-merohedral twin with a 0.518 (40.482 (1) component ratio