4,5,8a-Triphenyl-perhydro-pyrimido[4,5-d]pyrimidine-2,7-dione monohydrate

The title compound, C(24)H(22)N(4)O(2)·H(2)O, was synthesized by the trimethyl-chloro-silane-catalysed reaction between urea, benzaldehyde and acetophenone. The organic mol-ecule comprises two fused tetra-hydro-pyrimidinone rings with phenyl substituents at the 4- and 5-positions on the tetra-hydro-pyrimidinone rings and a third phenyl substituent at the ring junction 8-position. The 4- and 5-substituted phenyl rings are inclined at a dihedral angle of 22.72 (11)° to one another and make angles of 47.95 (7) and 65.76 (7)° with the third phenyl substituent. In the crystal structure, inter-molecular N-H⋯O contacts link pyrimido[4,5-d]pyrimidine mol-ecules into centrosymmetric dimers. Additional N-H⋯O and O-H⋯O hydrogen bonds involving the water mol-ecule generate a three-dimensional network.