3-epi-Dammarenediol II 1.075 hydrate: a dammarane triterpene from the bark of Aglaia eximia.

The title dammarane tritepene, 3α,20(S)-dihy-droxy-dammar-24-ene, which crystallized out in a hydrated form, C(30)H(52)O(2).1.075H(2)O, was isolated from the Aglaia eximia bark. The three cyclo-hexane rings adopt chair conformations. The cyclo-pentane has an envelope conformation with the quaternary C at position 14 as the flap atom with the maximum deviation of 0.288 (2) Å. The methyl-heptene side chain is disordered over two positions with 0.505 (1):0.495 (1) site occupancies and is axially attached with an (+)-syn-clinal conformation. The hydroxyl group at position 3 of dammarane is in a different conformation to the corresponding hydroxyl in Dammarenediol II. In the crystal, the dammarane and water mol-ecules are linked by O(Dammarane)-H⋯O(water) and O(water)-H⋯O(Dammarane) hydrogen bonds into a three-dimensional network.