2-Bromoethyl 2-chloro-6-methylquinoline-3-carboxylate

In the title compound, C13H11BrClNO2, the two rings of the quinoline group are fused in an axial fashion at a dihedral angle of 1.28 (9)°. In the crystal, molecules are arranged in zigzag layers along the c axis. The crystal packing is stabilized by weak C—H⋯O hydrogen bonds and intermolecular interactions between Br and O atoms [Br⋯O= 3.076 (2) Å], resulting in the formation of a three-dimensional network.

In the title compound, C 13 H 11 BrClNO 2 , the two rings of the quinoline group are fused in an axial fashion at a dihedral angle of 1.28 (9) . In the crystal, molecules are arranged in zigzag layers along the c axis. The crystal packing is stabilized by weak C-HÁ Á ÁO hydrogen bonds and intermolecular interactions between Br and O atoms [BrÁ Á ÁO= 3.076 (2) Å ], resulting in the formation of a three-dimensional network.
We are grateful to all personnel at the PHYSYNOR Laboratory, Université Mentouri-Constantine, for their assistance. Thanks are due to MESRS (Ministé re de l'Enseignement Supé rieur et de la Recherche Scientifique -Algé rie) for financial support.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BQ2201).

Comment
Benzylic bromination can be carried out using N-bromosuccinimide (NBS) under photocatalytic conditions (Djerassi, 1948;Newman et al., 1972). It is also known that NBS react with benzaldehyde diethylacetal to give corresponding ester (Marvell et al., 1951;Markees et al., 1958). Although extensive studies have been carried out in the past, selectivity clearly remains a common problem in radical bromination (Kikichi et al., 1998;Xu et al., 2003). In previous works, we have reported structure determination of some new quinoline derivatives (Benzerka et al., 2008;Ladraa et al., 2009;Ladraa et al., 2010). In this paper, we report the synthesis and structure determination of new compound, resulting from the radical bromination of 2-chloro-3-(1,3-dioxolan-2-yl)-6-methylquinoline, (I), under photocatalytic conditions. Our attempt to brominate the methyl group linked at C-6 position of quinoline ring, which has an acetal function at C-3, was failed and led to the 2-bromoethyl 2-chloro-6-methylquinoline-3-carboxylate (I). This compound is the result of the unwanted conversion of the acetal to the corresponding ester.
The molecular geometry and the atom-numbering scheme of (I) are shown in Figure 1. The asymmetric unit of title molecule contains a 2-bromoethylcarboxylate group linked to quinolyl moiety. The two rings of quinolyl moiety are fused in an axial fashion and form a dihedral angle of 1.28 (9)° The crystal structure can be described as layers in zig zag along of c-axis which quinoline rings are parallel to the (110) plane. The crystal packing is stabilized by weak hydrogen bonds  Table 1.

Experimental
The title compound (I) was synthesized by treating 1 mmol. of 2-chloro-3-(1,3-dioxolan-2-yl)-6-methylquinoline with 1 mmol. of N-bromosuccinimide in the presence of 0.5 mmol. of dibenzoylperoxide in CCl4 under photocatalytic conditions. The contents were then cooled and filtered off and the filtrate was concentrated under reduced pressure. The residue was subjected to column chromatography (silica gel, eluent: CH2Cl2) to afford pure product. Crystals suitable for x-ray analysis were obtained by slow evaporation of a dichloromethane solution of (I).

Refinement
All H atoms were localized on Fourier maps but introduced in calculated positions and treated as riding on their parent C atom. (with C-H = 0.93Å, 0.96Å, 0.97Å and U iso (H) =1.2 or 1.5(carrier atom)).
supplementary materials sup-2 Figures Fig. 1. (Farrugia, 1997) the structure of the title compound with the atomic labelling scheme. Displacement are drawn at the 50% 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.
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 Rfactors(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.