6-Hydroxy-salvinolone.

The title compound {systematic name: 5,6,10-trihydr-oxy-7-iso-propyl-1,1,4a-trimethyl-2,3,4,4a-tetra-hydro-phenanthren-9(1H)-one}, C(20)H(26)O(4), is a diterpenoid which was isolated from the roots of Premna obtusifolia. The mol-ecule has three fused six-membered rings; the cyclo-hexane ring is in a twisted-boat conformation and the cyclo-hexene ring adopts a sofa form. Intra-molecular O-H⋯O hydrogen bonds generate two S(5) ring motifs. In the crystal, mol-ecules are linked into infinite one-dimensional chains along the [001] direction by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions.