2-[(3S,3aS,5R,8S,8aS)-3,8-Di­methyl­hexa­hydro-1H,4H-3a,8a-ep­oxy­azulen-5-yl]propan-2-ol

Four independent mol­ecules (A–D) comprise the asymmetric unit of the title compound, C(15)H(26)O(2), which differ only in the relative orientations of the terminal –C(Me)(2)OH groups [e.g. the range of C(methyl­ene)—C(methine)—C(quaternary)—O(hy­droxy) torsion angles is 52.7 (7)–57.1 (6)°, where the C(methyl­ene) atom is bound to an epoxide C atom]. The five-membered rings adopt envelope conformations, with the methyl­ene C atom adjacent to the methine C atom being the flap atom in each case. In each mol­ecule, the conformation of the seven-membered ring is a half-chair, with the C(methyl­ene)—C(methine) bond, flanked by methyl­ene C atoms, being the back of the chair. Supra­molecular helical chains along the b axis are found in the crystal packing, sustained by hy­droxy–epoxide O—H⋯O hydrogen bonding. Mol­ecules of A self-associate into a chain as do those of D. A third independent chain comprising B and C mol­ecules is also formed. The studied crystal is a pseudo-merohedral twin (minor component ca 21%).