14,15-Didehydro­hellebrigenin

The title compound, C(24)H(30)O(5), is the didehydro product of the steroid hellebrigenin (systematic name: 3β,5,14-trihy-droxy-19-oxo-5β-bufa-20,22-dienolide). It consists of three cyclo-hexane rings (A, B and C), a five-membered ring (D) and a six-membered lactone ring (E). The stereochemistry of the ring junctions are A/B cis, B/C trans and C/D cis. Cyclo-hexane rings A, B and C have normal chair conformations. The five-membered ring D with the C=C bond adopts an envelope conformation. Lactone ring E is essentially planar with a mean derivation of 0.006 (4) Å and is β-oriented at the C atom of ring D to which it is attached. There is an O-H⋯O hydrogen bond in the mol-ecule involving the hy-droxy groups. In the crystal, O-H⋯O hydrogen bonds link the mol-ecules into chains propagating along [010]. The chains are linked by C-H⋯O contacts into a three-dimensional network.