9,9-Dimethoxy-7,11-diphenyl-2,4-diazaspiro[5.5]undecane-1,3,5-trione monohydrate.

Due to steric repulsions, the cyclohexane ring in the title compound, C(23)H(24)N(2)O(5).H(2)O, shows some bond-length abnormalities and adopts a chair conformation. The pyrimidine and cyclohexane rings are approximately perpendicular to each other, and the phenyl rings are equatorial. C-H.pi and N-H.O intermolecular interactions, as well as C-H.O inter- and intramolecular interactions, occur between the molecules. In addition to van der Waals interactions, the water molecule interacts with the pyrimidinetrione ring to stabilize the structure.