3β-Hydroxy-28-norolea-12,17-dien-11-one

Abstract

The title compound, C29H44O2, was formed by treatment of 11-oxooleanolic acid under strong alkaline conditions. The absolute structure of the chiral molecules could not be determined reliably from the diffraction data, but is known from other triterpenes. The asymmetric unit consists of two molecules, 1 and 2. In both molecules, rings A and B show chair conformations. The other rings show mixed forms between envelope and half-chair conformations with atoms in positions 8, 15 and 21 forming the flaps in rings C, D and E, respectively. Rings D and E of molecule 2 are disordered over two orientations, with occupancies of 0.557 (4) and 0.443 (4), which differ in the direction of the flap in ring E. In the crystal, molecules 1, as well as the molecules 2, are linked by O—H...O hydrogen bonds, forming chains parallel to the b axis.

Keywords

• crystal structure