title: (20S*,24S*)-25-Hy-droxy-20,24-ep-oxy-A-homo-4-oxadammaran-3-one (Chrysura) isolated from the leaves of Walsura chrysogyne.
abstract: The title dammarane triterpenoid, C(30)H(50)O(4), assigned the name chrysura, was isolated from an ethyl acetate extract of Walsura chrysogyne leaves (Meliaceae). It has 20S*,24S* relative stereochemistry and an oxepanone ring with two methyl groups at position 4. The two cyclo-hexane rings adopt chair conformations. The cyclo-pentane and tetra-hydro-furan rings have envelope conformations; their mean planes make a dihedral angle of 13.1 (3)°, indicating that the rings are only slightly tilted with respect to each other. There is an intra-molecular C-H⋯O hydrogen bond in the mol-ecule, which forms S(6) and S(7) ring motifs. In the crystal, mol-ecules are linked via O-H⋯O and C-H⋯O hydrogen bonds, forming chains propagating along [001] which stack along the b-axis direction.
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor,  Malaysia.
authors.forename: Ilya Iryani
authors.initials: II
authors.lastname: Mahmod
authors.forename: Huey Chong
authors.initials: HC
authors.lastname: Kwong
authors.forename: Mohamed Ibrahim
authors.initials: MI
authors.lastname: Mohamed Tahir
authors.forename: Intan Safinar
authors.initials: IS
authors.lastname: Ismail