Crystal structure of rac-(3aR,4S,5aR,6S,9R,10aS,10bR)-3a,5a,9-tri­methyl­tetra­deca­hydro-6,9-ep­oxy­cyclo­hepta­[e]inden-4-ol monohydrate

The title hydrate, C(17)H(28)O(2)·H(2)O, was synthesized in order to determine the relative configuration of the tetra­cyclic framework. The fused 5,6,7-tricarbocyclic core exhibits an entire cis-annulation, featuring a 1,4-cis-relation of the angular methyl groups in the six-membered ring. The oxa bridge of the ep­oxy­cyclo­heptane moiety is oriented towards the concave face of the boat-shaped mol­ecule, whereas the angular methyl groups are directed towards the convex face. The asymmetric unit of the crystal contains two nearly identical formula units, which are related via a pseudo-centre of symmetry. The structure could be solved in the space groups I-4 and I4(1)/a. The refinement in the acentric space group, however, gave significantly better results and these are used in this paper. O—H⋯O hydrogen bonds are observed between the organic mol­ecules, between the organic mol­ecules and the water mol­ecules, and between the water mol­ecules, forming a chain along the c-axis direction.