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

In the title molecule, C19H20O6, the conformation about the C=C bond of the central enone group is E. The dihedral angle formed by the benzene rings is 11.6 (2)°. The hydroxy group is involved in an intramolecular O—H⋯O hydrogen bond. In the crystal, weak C—H⋯O hydrogen bonds link the molecules into chains along [010].


Comment
A variety of chlacones have been isolated from natural sources and synthesized, because they have shown wide spectrum of biological activities including anticancer (Shin et al., 2013), anti-diabetic (Hsieh et al., 2012, anti-inflammatory (Sashidhara et al. 2011), andantimicrobial (Sharma et al., 2012). Chalcones are one of the secondary metabolites found in plants with a C6-C3-C6 skeleton and a C3 skeleton is an α,β-unsaturated carbonyl (enone). In continuation of our research interests to develop novel chalcones which show broad range of biological activities (Shin et al., 2013, Yong et al., 2013, the crystal structure of title compound has been determined.
The molecular structure of the title compound is shown in Fig. 1

Experimental
To a solution of 2-hydroxy-6-methoxyacetophenone (332 mg, 2 mmol) in 20 ml of anhydrous ethanol was added 2,4,6trimethoxybenzaldehyde (392 mg, 2 mmol) and the temperature was adjusted to around 276-277 K in an ice-bath. To the cooled reaction mixture was added 2 ml of 50% aqueous KOH solution, and the reaction mixture was stirred at room temperature for 48 h. This mixture was poured into iced water (100 ml) and was acidified with 6 N HCl solution. The mixture was extracted with ethylacetate (3×20 ml) and the combined organic layers were dried under MgSO 4 . Filtration and evaporation of the filtrate gave a residue which was purified by flash chromatography to afford the title compound (255 mg, 34%). Recrystallization of the title compound in ethanol gave single crystals (mp: 401-402 K).

Refinement
H atoms were placed in calculated positions and refined as riding with C-H = 0.95-0.98 Å, O-H = 0.84 Å and U iso (H) = 1.2 U eq (C) or U iso (H) = 1.5U eq (C methyl , O).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.