Methyl (2Z)-2-bromomethyl-3-(3-chlorophenyl)prop-2-enoate

There are two independent molecules (A and B) in the asymmetric unit of the title compound C11H10BrClO2, which represents the Z isomer. The methylacrylate moieties are essentially planar, within 0.084 (2) and 0.027 (5) Å in molecules A and B, respectively. The benzene ring makes dihedral angles of 13.17 (7) and 27.89 (9)° with the methylacrylate moiety in molecules A and B, respectively. The methylbromide moiety is almost orthogonal to the benzene ring, making dihedral angles of 81.46 (16)° in molecule A and 79.61 (16)° in molecule B. The methylacrylate moiety exhibits an extended trans conformation in both molecules. In the crystal, pairs of C—H⋯O hydrogen bonds result in the formation of quasi-centrosymmetric R 2 2(14) AB dimers.

There are two independent molecules (A and B) in the asymmetric unit of the title compound C 11 H 10 BrClO 2 , which represents the Z isomer. The methylacrylate moieties are essentially planar, within 0.084 (2) and 0.027 (5) Å in molecules A and B, respectively. The benzene ring makes dihedral angles of 13.17 (7) and 27.89 (9) with the methylacrylate moiety in molecules A and B, respectively. The methylbromide moiety is almost orthogonal to the benzene ring, making dihedral angles of 81.46 (16) in molecule A and 79.61 (16) in molecule B. The methylacrylate moiety exhibits an extended trans conformation in both molecules. In the crystal, pairs of C-HÁ Á ÁO hydrogen bonds result in the formation of quasi-centrosymmetric R 2 2 (14) AB dimers.

Experimental
To a stirred solution of methyl 2-((3-chlorophenyl)(hydroxy)methyl) acrylate (4 mmol) in CH 2 Cl 2 (15 ml), 48% aqueous HBr (0.68 ml) was added at room temperature. The reaction mixture was cooled to 273 K and then catalytic amount of concentrated H 2 SO 4 was added dropwise. The reaction mixture was stirred well at room temperature for about 24 hrs.
After the completion of the reaction (confirmed by TLC analysis), the reaction mixture was poured into water and the aqueous layer was extracted with ethyl acetate (3 x 10 ml). The combined organic layer was washed with brine (10 ml) and concentrated. The crude product thus obtained was purified by column chromatography (EtOAc/Hexane, 2-6%) to provide Methyl (2Z)-2-(bromomethyl)-3-(3-chlorophenyl)prop-2-enoate in 90% yield, as a yellow crystalline solid.

Refinement
Hydrogen atoms were placed in calculated positions with C-H = 0.93 -0.97 Å and refined in riding model with fixed isotropic displacement parameters: U iso (H) = 1.2 U eq (C) for aromatic and methylene groups U iso (H) = 1.5 U eq (O) for methyl group. The rotation angles for methyl group were optimized by least squares.   The crystal structure of the title compound, showing the formation of quasi-centrosymmetric R 2 2 (14) dimers. Hydrogen bonds are shown as dotted lines. The hydrogen atoms not involved in bonding have been omitted for the sake of clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.85 e Å −3 Δρ min = −0.49 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.