1-Hydroxy-3,4-dimethoxy-10-methylacridin-9-one

The title compound was isolated from fruits of Zanthoxylum leprieurii. The atoms of the three rings of the molecule are coplanar. In the crystal, C—H⋯·O hydrogen-bonding interactions link the molecules into a three-dimensional network.

There are two independent molecules in the asymmetric unit of the title compound, C 16 H 15 NO 4 , which was isolated from fruits of Zanthoxylum leprieurii. The atoms of the three rings of each molecule are close to coplanar with the largest deviations from the least-squares planes being 0.084 (3) Å and 0.069 (2) Å . Each molecule features an intramolecular O-HÁ Á ÁÁO hydrogen bond. In the crystal, C-HÁ Á ÁÁO hydrogen-bonding interactions link the molecules into a three-dimensional network.
One of the most important secondary metabolites described in Z. leprieurii are acridone derivatives (Ngoumfo et al., 2010), of which we can highlight 1-hydroxy-3,4dimethoxy-N-methylacridone, which was first described by Baudouin et al. (1985) and has been isolated and evaluated for its bioactive potential in a single or synergistic action with other natural constituents (Baudouin et al., 1985). For background to 1-hydroxy-3,4dimethoxy-N-methyl-acridone, see: Ladino & Suá rez (2010). In this work, we describe the crystal structure of the title compound, isolated from Z. leprieurii.
In the crystal molecules are linked by weak C-HÁ Á ÁO interactions (Table 1).

Synthesis and crystallization
The powder obtained after the pulverization of the plant material was soaked in a mixture of methylene chloride and methanol. The crude extract was subjected to chromatography on a silica gel column eluted with an increasing polarity of ethyl acetate in hexane. The title compound, red in colour, soluble in acetone was obtained from fractions 111-120 (90 mg) by recrystallization from hexane/ethyl acetate 80/20 solution. The solvent used for single-crystal formation was absolute ethanol.
Spectroscopic data the title compound are in agreement with literature data (Baudouin et al., 1985).

Figure 1
The asymmetric unit of the title compound showing the atom labelling and 50% probability displacement ellipsoids.

data-1
IUCrData ( Hydrogen site location: mixed H atoms treated by a mixture of independent and constrained refinement Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.93 Å (rings) or C-H = 0.96 Å (methyl snd hydroxy) with U iso (H) = 1.2U eq (C).