Lup-20(29)-en-28-ol-3-one (betulone)

Acta Crystallogr Sect E Struct Rep Online. 2013 Apr 27;69(Pt 5):o795-6. doi: 10.1107/S1600536813011008. Print 2013 May 1.

Abstract

The asymmetric unit of the title compound, C30H48O2, contains two independent mol-ecules, the main difference between them being that the isopropenyl group is rotated by approximately 180°. In each mol-ecule, the fused six-membered rings have chair-chair-chair-chair conformations and the cyclo-pentane ring adopts an envelope conformation with the C atom bearing the hy-droxy-methyl group as the flap. All ring junctions are trans-fused. With the exception of one of the methyl groups adjacent to the C=O group, all the methyl groups are in axial positions. The isopropenyl group is equatorial and the hy-droxy-methyl group is in an axial orientation. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into chains along [010]. Weak intra-molecular C-H⋯O hydrogen bonds are also observed but the hy-droxy groups are not involved in hydrogen bonds.