(Z)-Ethyl 2-hy-droxy-4-oxo-4-(1,4,5,6,8-penta-meth-oxy-naphthalen-2-yl)but-2-enoate

The title compound, C21H24O9, crystallizes with two independent mol-ecules in the asymmetric unit which are almost centrosymmetrically related to each other. The ethano-ate group in one of the two mol-ecules is disordered over two positions with a site-occupation factor of 0.880 (7) for the major occupied site. In the crystal, the 1,3-diketone group exists in the keto-enol isomeric form due to the stabilizing effect of the intra-molecular O-H⋯O hydrogen bond present in this form. The compound packs as a layered structure in which C-H⋯π and C-H⋯O inter-actions are present within and between the layers.