(Z)-Ethyl 2-hy­droxy-4-oxo-4-(1,4,5,6,8-penta­meth­oxy­naphthalen-2-yl)but-2-enoate

The title compound, C(21)H(24)O(9), crystallizes with two independent mol­ecules in the asymmetric unit which are almost centrosymmetrically related to each other. The ethano­ate group in one of the two mol­ecules 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 intra­molecular 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 inter­actions are present within and between the layers.