Unusual hemiacetal structure derived from Salvinorin A

The salvinorin A analog dimethyl (2R,3aR,4R,6aR,7R,9S,9aS,9bS)-2-(3-fur­yl)-9,9a-dihydr­oxy-3a,6a-dimethyl­dodeca­hydro­benzo[de]chromene-4,7-dicarboxyl­ate, C(22)H(30)O(8), has a relatively simple spatial arrangement in which mol­ecules are linked into layers by two pairs of O—H⋯O hydrogen bonds. Each mol­ecule has as the central feature a dodeca­hydro-1H-phenalene ring system. Its three six-membered rings are in the chair conformation, with two axial methyl groups, one axial OH, and one equatorial OH, these OH groups being directly responsible for linking of the mol­ecules in the crystal structure.