(E)-5-[1-Hy-droxy-3-(3,4,5-tri-meth-oxy-phen-yl)allyl-idene]-1,3-di-methyl-pyrimidine-2,4,6-trione: crystal structure and Hirshfeld surface analysis.

In the title compound, C18H20N2O7, the dihedral angle between the aromatic rings is 7.28 (7)° and the almost planar conformation of the mol-ecule is supported by an intra-molecular O-H⋯O hydrogen bond, which closes an S(6) ring. In the crystal, weak C-H⋯O hydrogen bonds and aromatic π-π stacking link the mol-ecules into a three-dimensional network. A Hirshfeld surface analysis showed that the major contribution to the inter-molecular inter-actions are van der Waals inter-actions (H⋯H contacts), accounting for 48.4% of the surface.