Synthesis and crystal structure of (2E)-1-[3,5-bis(benzyloxy)phenyl]-3-(4-ethoxyphenyl)prop-2-en-1-one

In the title compound, the phenyl rings of the chalcone unit subtend a dihedral angle of 26.43 (10)°. The phenyl rings of the pendant benzyloxy groups are orientated at 75.57 (13) and 75.70 (10)° with respect to their attached ring. In the crystal, weak C—H⋯O and C—H⋯π interactions link the molecules, forming C(15) chains propagating along [101].


Chemical context
Chalcones incorporate an �,�-unsaturated carbonyl (enone) bridge connecting two aromatic rings.The chalcone scaffold exhibits anti-cancer efficacy on various human cancer cells (Zhuang et al., 2017;Liu et al., 2022).DrugBank lists three chalcone-based drugs namely hesperidin methylchalcone (DrugBank: DB15943), dihydroxymethoxychalcone (DB14122) and 3-(4-hydroxyphenyl)prop-2-en-1-one (DB07500).In general, the anticancer efficacy of chalcones is enhanced by attaching different substitutents at ring A of the chalcone, which is attached to the C O group (Mai et al., 2014).As part of our studies in this area, we have prepared and undertaken a single-crystal X-ray diffraction study of the title compound, C 31 H 28 O 4 , (I), and the results are presented here.

Hirshfeld surface analysis
To further characterize the intermolecular interactions in (I), a Hirshfeld surface analysis was performed using Crystal Explorer 21 (Spackman et al., 2021) and the associated two dimensional fingerprint plots were generated.The HS mapped over d norm in the range À 0.09 to +1.53 a.u. is illustrated in Fig. 4, using colours to indicate contacts that are shorter (red areas), equal to (white areas), or longer than (blue areas) the sum of the van der Waals radii (Ashfaq et al., 2021).
Cg1 is the centroid of the C26-C31 ring.

Figure 2
Detail of the packing of (I) showing C-H� � �O interactions as dashed lines.For clarity H atoms not involved in these hydrogen bonds have been omitted.

Figure 4
A view of the Hirshfeld surface mapped over d norm for (I).due to the large hydrogen content of the molecule with the tip at d e = d i = 1.10A ˚.As a result of the presence of C-H� � �O interactions, the H� � �O/O� � �H contacts contribute 13.6% to the overall crystal packing, as reflected in Fig. 5d with the tips at d e + d i = 2.50 A ˚.

Synthesis and crystallization
Equimolar concentrations of 3,5-dibenzyloxyacetophenone and 4-ethoxybenzaldehyde were dissolved in ethanol in separate reaction flasks and then mixed.Drop by drop, utilizing a magnetic stirring device, 2 ml of 10% sodium hydroxide in water were introduced at room temperature.The course of the process was tracked using thin-layer chromatography.After the process was complete, the resulting product was placed on crushed ice.The finished product was vacuumfiltered, dried, and then recrystallized from ethanol solution to yield colourless blocks of the title compound.

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.

Figure 3
Figure 3Detail of the packing of (I) showing C-H� � �� interactions as dashed lines.

Table 2
Experimental details.