title: (Z)-Ethyl 2-hy-droxy-4-oxo-4-(1,4,5,6,8-penta-meth-oxy-naphthalen-2-yl)but-2-enoate.
abstract: 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.
authors.affiliation: Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, Johannesburg, South Africa.
authors.forename: Adushan
authors.initials: A
authors.lastname: Pillay
authors.forename: Sanaz
authors.initials: S
authors.lastname: Khorasani
authors.forename: Charles B
authors.initials: CB
authors.lastname: de Koning