meso-4,4 '-Dimethoxy-2,2 '-{[(3aR,7aS)-2,3,3a,4,5,6,7,7a-octahydro-1H-benzimidazole-1,3-diyl]bis(methylene)}diphenol

The title compound, C23H30N2O4, a di-Mannich base derived from 4-methoxyphenol and cis-1,2-diaminecyclohexane, has a perhydrobenzimidazolidine nucleus, in which the cyclohexane ring adopts a chair conformation and the heterocyclic ring has a half-chair conformation with a C - N - C - C torsion angles of -48.14 (15) and -14.57 (16)degrees. The mean plane of the heterocycle makes dihedral angles of 86.29 (6) and 78.92 (6)degrees with the pendant benzene rings. The molecular structure of the title compound shows the presence of two interactions between the N atoms of the imidazolidine ring and the hydroxyl groups through intramolecular O-H center dot center dot center dot N hydrogen bonds with graph-set motif S(6). The unobserved lone pairs of the N atoms are presumed to be disposed in a syn conformation, being only the second example of an exception to the typical 'rabbit-ears' effect in 1,2-diamines.