(20S)-Dammar-24-ene-3Β,20-diol monohydrate from the bark of Aglaia exima (Meliaceae)

Abstract

In the title compound {systematic name: (1R,2R,5R,7R,10R,11R,14S,15R)-14- [(2S)-2-hydroxy-6-methyl-hept-5-en-2-yl]-2,6,6,10,11-penta-methyl-tetra-cyclo- [8.7.0.02,7.011,15]hepta-decan-5-ol monohydrate}, C 30H52O2·H2O, the three fused cyclo-hexane rings adopt chair conformations and the hydroxy substituent of one of these occupies an axial position. The fused cyclo-pentane ring adopts an envelope conformation (with the flap atom being the C atom bearing the methyl group) and the 3-methyl-but-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 O 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 (1):0.482 (1) component ratio.