(E)-1-(2-Furyl)-3-(2,4,6-trimethoxyphenyl)prop-2-en-1-one

In the title heteroaryl chalcone derivative, C16H16O5, the dihedral angle between the furan and benzene rings is 14.45 (6)°. The three methoxy groups are almost coplanar with their attached benzene ring [C—C—O—C torsion angles = 2.07 (17), −5.04 (17) and 2.85 (16)°]. An intramolecular C—H⋯O hydrogen bond occurs. In the crystal, adjacent molecules are linked into X-shaped chains along the c axis by weak C—H⋯O(enone) interactions. These chains are stacked along the b axis. C⋯O [3.3308 (13)–3.4123 (14) Å] short contacts are also observed.

In the crystal packing, all the three methoxy groups involve in weak intermolecular C-H···O interactions ( Table 1). The adjacent molecules are linked into X-shape chains along the c axis through the enone unit by weak C-H···O interactions ( Fig. 2, Table 1). The adjacent chains are arranged into face-to-face manner (Fig. 3) and stacked along the b axis (Fig. 3).

Experimental
The title compound was prepared by the condensation of the solution of 2-furyl methylketone (2 mmol, 0.22 g) in ethanol (15 ml) and 2,4,6-trimethoxybenzaldehyde (2 mmol, 0.40 g) in ethanol (15 ml) in the presence of 20% NaOH (aq) 5 ml at 278 K for 5 hr. The resulting solid which was obtained was further collected by filtration, washed with distilled water and dried in air. Colorless blocks of (I) were recrystalized from acetone/ethanol (1:1 v/v) by the slow evaporation of the solvent at room temperature after several days, Mp. 390-391 K.

Refinement
All H atoms were located in difference maps and refined isotropically. The highest residual electron density peak is located at 0.63 Å from C10 and the deepest hole is located at 1.12 Å from C2. Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids. Weak intramolecular interactions are shown as dashed lines. sup-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.