Methyl (Z)-2-[(4-bromo-2-formylphenoxy)methyl]-3-(4-methylphenyl)acrylate

In the title compound, C19H17BrO4, the dihedral angle between the two benzene rings is 82.9 (2)°. The molecular structure is stabilized by an intramolecular C—H⋯O hydrogen bond, which generates an S(7) ring motif. The crystal packing is stabilized by C—H⋯O hydrogen bonds, which generate two centrosymmetic ring systems with R22(18) and R22(14) graph-set motifs. The crystal packing is further stabilized by intermolecular π–π interactions [centroid–centroid distance = 3.984 (2) Å].

In the title compound, C 19 H 17 BrO 4 , the dihedral angle between the two benzene rings is 82.9 (2) . The molecular structure is stabilized by an intramolecular C-HÁ Á ÁO hydrogen bond, which generates an S(7) ring motif. The crystal packing is stabilized by C-HÁ Á ÁO hydrogen bonds, which generate two centrosymmetic ring systems with R 2 2 (18) and R 2 2 (14) graph-set motifs. The crystal packing is further stabilized by intermolecularinteractions [centroidcentroid distance = 3.984 (2) Å ].
The formation of the framework can be explained in terms of two-one substructures. In the first substructure C4-H4···O2 at (x, y, z and 1 -x, -y, -z) and C18-H18···O1 at (x, y, z and 1 -x, -1 -y, 1 -z) hydrogen bonding interactions form a cyclic centrosymmetric pattern, with the graph set motif R 2 2 (18) and R 2 2 (14), respectively. These combine to form zigzag chains which propagate along [001] (Fig. 2). In the second substructure, atom C5 in the molecule at (x, y, z) acts as a hydrogen bond donor to atom O4 in the molecule at (1 + x, y, z) generating C(6) chains which are running along [100] (Fig. 3). The crystal packing is further stabilized by an intermolecular π-π interactions with Cg-Cg i separation of 3.984 (2) Å ( Fig. 4; Cg is the centroid of the (C13-C18) benzene ring).

Experimental
A solution of 5-bromo-2-hydroxybenzaldehyde (1.0 mmol, 0.201 g) and potassium carbonate (1.5 mmol, 0.207 g) in acetonitrile solvent (10 ml) was stirred for 15 minutes at room temperature. To this solution, (Z-methyl 2-(bromomethyl)-3-p-tolylacrylate (1.2 mmol, 0.324 g) was added dropwise till the addition is complete. After the completion of the reaction as indicated by TLC, acetonitrile was evaporated. Ethylacetate (15 ml) and water (15 ml) were added to the crude mass and extracted. The organic layer was dried over anhydrous sodium sulfate. Removal of solvent led to the crude product, which was purified through pad of silica gel (100-200 mesh) using ethylacetate and hexanes (1:9) as solvents. The pure title compound was obtained as a colorless solid (0.350 g, 90% yield). Single crystals suitable for Xray diffraction were obtained by slow evaporation of a ethylacetate solution at room temperature.

Refinement
All the H atoms were positioned geometrically, with C-H = 0.93-0.97 Å and constrained to ride on their parent atom, with U iso (H) =1.5U eq for methyl H atoms and 1.2U eq (C) for other H atoms.

Figure 1
The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as a small spheres of arbitrary radius.     where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.67 e Å −3 Δρ min = −0.41 e Å −3

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.