8-O-Acetyl-8-epi-9-deoxygoniopypyrone

The title compound (systematic name: 7-oxo-3-phenyl-2,6-dioxabicyclo[3.3.1]nonan-4-yl acetate), C15H16O5, is a styryllactone derivative which was isolated from Goniothalamus macrophyllus. The molecule has two fused rings consisting of a tetrahydro-2H-pyran and a lactone ring, with the benzene ring and the acetyl group attached to the tetrahydro-2H-pyran ring. The tetrahydro-2H-pyran ring is in a standard chair conformation, whereas the lactone ring is in an envelope conformation. In the crystal, molecules are linked by weak C—H⋯O interactions into sheets parallel to the ac plane. Weak C—H⋯π interactions are also observed.

umbrosus showed antoxidant, antibacterial and antiviral activities (Abdul-Wahab et al., 2011). The previous reports by Goh et al. (1995) and Jiang et al. (2011) showed that plants in Goniothalamus genus produce styryllactone compounds as major constituents and most of them exhibit potent cytotoxic activity. The above investigations has prompted us to search for cytotoxic components from Goniothalamus plants. Our research on bioactive compounds from G. macrophyllus yields the title compound (I), 8-O-Acetyl-8-epi-9-deoxygoniopypyrone. Herein the crystal structure of (I) was reported.
In the crystal packing ( Fig. 2), the molecules are linked into sheets parallel to the ac plane by weak C-H···O interactions (Table 1). Weak C-H···π interactions (Table 1) are also observed.

Experimental
The title compound was isolated from the methanolic extract of the G. macrophyllus by repeated column chromatography. Single crystals suitable for X-ray structure determination were obtained as colorless block-shaped crystals by slow evaporation of the solvent at room temperature after several days. M. p. 467-469 K.

Refinement
All H atoms were located in difference maps and refined isotropically. A total of 2473 Friedel pairs were merged before final refinement as there is no large anomalous dispersion for the determination of the absolute configuration.

Figure 1
The molecular structure of the title compound, showing 50% probability displacement ellipsoids.

Figure 2
The crystal packing of the title compound viewed along the b axis, showing a sheet of molecules parallel to the ac plane.
Weak C-H···O interactions are shown as dashed lines. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.36 e Å −3 Δρ min = −0.21 e Å −3 Special details Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 120.0 (1) K. 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. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.