The title dammarane triterpenoid, C30H50O4, 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 cyclohexane rings adopt chair conformations. The cyclopentane and tetrahydrofuran 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 intramolecular C—H
O hydrogen bond in the molecule, which forms S(6) and S(7) ring motifs. In the crystal, molecules are linked via O—H
O and C—H
O hydrogen bonds, forming chains propagating along [001] which stack along the b-axis direction.
O hydrogen bond in the molecule, which forms S(6) and S(7) ring motifs. In the crystal, molecules are linked via O—H
O and C—H
O hydrogen bonds, forming chains propagating along [001] which stack along the b-axis direction.


![[triangle]](/corehtml/pmc/pmcents/rtrif.gif)


and ω scans