Ethyl 2-[(E)-({2,4-dimethoxy-6-[2-(4-methoxyphenyl)ethenyl]benzylidene}amino)oxy]acetate

The crystal structure of a resveratrol–oxime ester is reported.


Synthesis and crystallization
A mixture of E-2,4-dimethoxy-6-(4-methoxystyryl)benzaldehyde (298 mg, 1 mmol; Ge et al., 2013) and hydroxylamine hydrochloride (69 mg, 1 mmol) in 15 ml of ethanol-water (1:1) was refluxed for 4 h. After completion of reaction, the mixture was cooled to room temperature to give the corresponding oxime derivative (86%, m.p. = 150-152 C), which was used for the next reaction. To a mixture of the oxime derivative (156 mg, 0.5 mmol) and potassium carbonate (276 mg, 2 mmol) in 10 ml of DMF, 1.2 equivalents of ethyl bromoacetate (100 mg, 0.6 mmol) were added and heated for 5 h at 60 C. After completion of the reaction, the reaction mixture was poured into crushed ice-water to form a precipitate. The resulting solid was separated by filtration and was washed with ethyl acetate. Recrystallization of the solid from ethyl acetate solution gave colourless blocks of the title compound.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.

Funding information
This work was supported by a Dongduk Women's University grant.

Figure 2
A view of the inversion dimer formed by a pair of C-HÁ Á ÁN hydrogen bonds (dashed lines) in the crystal structure of the title compound, generating an R 2 2 (14) loop. For clarity, only those H atoms involved in hydrogen bonding are shown.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level.
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.

data-2
IUCrData (2021). 6, x210950 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.