4,4′-Dimethyl-2,2′-{[2,3,3a,4,5,6,7,7a-octa­hydro-1H-benzimidazole-1,3-di­yl]bis­(methyl­ene)}diphenol

The asymmetric unit of the title compound, C₂₃H₃₀N₂O₂, contains one half-mol­ecule, with a twofold axis splitting the mol­ecule in two identical halves. The structure of the racemic mixture has been reported previously [Rivera et al. (2009) J. Chem. Crystallogr. 39, 827–830] but the enanti­omer reported here crystallized in the ortho­rhom­bic space group P2₁2₁2 (Z = 2), whereas the racemate occurs in the triclinic space group P-1 (Z = 2). The observed mol­ecular conformation is stabilized by two intra­molecular O—H...N hydrogen bonds, which generate rings with graph-set motif S(6). In the crystal, mol­ecules are linked via non-classical C—H...O inter­actions, which stack the mol­ecules along the b axis.