title: Methyl 7,8-diacet-oxy-11-oxo-5-(2-oxo-pyrrolidin-1-yl)-7,9-epoxy-cyclo-penta-[4,5]pyrido[1,2-a]quinoline-10-carboxyl-ate sesquihydrate.
abstract: The title compound, C(26)H(28)N(2)O(9)·1.5H(2)O, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as a sesquihydrate with the O atom of one of the two independent water mol-ecules occupying a special position on a twofold axis. The organic mol-ecule comprises a fused penta-cyclic system containing two five-membered rings (cyclo-pentane and tetra-hydro-furan) and three six-membered rings (piperidinone, tetra-hydro-pyridine and benzene). The five-membered rings have the usual envelope conformations, and the central six-membered piperidinone and tetra-hydro-pyridine rings adopt boat and sofa conformations, respectively. In the crystal, there are three independent O-H⋯O hydrogen bonds, which link the organic mol-ecules and water mol-ecules into complex two-tier layers parallel to (001). The layers are further linked into a three-dimensional framework by attractive inter-molecular carbon-yl-carbonyl inter-actions.
authors.forename: Atash V
authors.initials: AV
authors.lastname: Gurbanov
authors.forename: Eugeniya V
authors.initials: EV
authors.lastname: Nikitina
authors.forename: Vladimir P
authors.initials: VP
authors.lastname: Zaytsev
authors.forename: Fedor I
authors.initials: FI
authors.lastname: Zubkov
authors.forename: Victor N
authors.initials: VN
authors.lastname: Khrustalev