4-Bromomethyl-7,8-dimethylcoumarin

In the title molecule, C12H11BrO2, all non-H atoms with the exception of the Br atom are essentially coplanar (r.m.s. deviation = 0.018 Å). The C—Br bond is inclined by 80.17 (12)° to this plane. The crystal structure is stabilized by weak C—H⋯O hydrogen bonds.

In the title molecule, C 12 H 11 BrO 2 , all non-H atoms with the exception of the Br atom are essentially coplanar (r.m.s. deviation = 0.018 Å ). The C-Br bond is inclined by 80.17 (12) to this plane. The crystal structure is stabilized by weak C-HÁ Á ÁO hydrogen bonds.
RG thanks MVJ College of Engineering, Bangalore (VTU Research center), for providing research facilities. The authors also thank the SAIF IIT Madras, Chennai, for the data collection.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5165).

Comment
The title compound has potential use in Heck and Suzuki cross coupling reactions (Cui et al., 2007) and Negishi coupling reactions (Zhao et al., 2008). In continuation of our work on the crystal structures of halogenated coumarin derivatives (Gowda et al., 2009;2010) herein we report crystal structure of title compound.
The molecular structure of the title compound is shown in Fig. 1

Experimental
To a mixture of equimolar quantities of 2,3-dimethylphenol (0.1 mol) and 4-bromoethylacetoacetate (0.1 mol), sulfuric acid (30 ml) was added dropwise with stirring while maintaining the temperature between 273-278K. The reaction mixture was allowed to stand in ice chest overnight and the deep red coloured solution was poured into a stream of crushed ice. The solid which separated was filtered and washed with water and then with cold ethanol to yield a colourless compound which was recrystallized from acetic acid.

Refinement
All H atoms were positioned geometrically and refined using a riding model with bond lengths 0.96 (methyl) or 0.93 Å (aromatic) and U iso (H) = 1.5U eq (C) for methyl groups and U iso (H) = 1.2U eq (C) for all other H atoms. Fig. 1. The molecular structure of the title compound shown with 50% probability displacement ellipsoids.

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 > 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.