3-Chloromethyl-6,7-dimethyl-1,2-benzoxazole

In the title compound, C10H10ClNO, the benzoisoxazole ring is almost planar (r.m.s. deviation = 0.0121 Å) and the chloro substituent in the side chain is anticlinal relative to the N—C bond of the isoxazole ring. In the crystal, adjacent molecules are linked via a pair of weak C—H⋯N hydrogen bonds, forming dimers through a cyclic R 2 2(8) association.

In the title compound, C 10 H 10 ClNO, the benzoisoxazole ring is almost planar (r.m.s. deviation = 0.0121 Å ) and the chloro substituent in the side chain is anticlinal relative to the N-C bond of the isoxazole ring. In the crystal, adjacent molecules are linked via a pair of weak C-HÁ Á ÁN hydrogen bonds, forming dimers through a cyclic R 2 2 (8) association.   Table 1 Hydrogen-bond geometry (Å , ). supplementary materials Acta Cryst. (2012). E68, o3008 [doi:10.1107/S1600536812039700] 3-Chloromethyl-6,7-dimethyl-1,2-benzoxazole M. Kayalvizhi, G. Vasuki, A. Veerareddy and G. Laxminarasimha Comment The benzoxazole ring system is one of the most common heterocycles in medicinal chemistry (Qu et al., 2008). Isoxazole derivatives bearing various substituents are known to have diverse biological activities in pharmaceutical and agricultural areas (Ha et al., 2010). In agriculture applications herbicidal activity has been identified (Raju et al., 2002) as well as fungicidal activities against some plant pathogens (Ha et al., 2010). Some derivatives are also used as semiconductors and as corrosion inhibitors in fuels and lubricants (Raju et al., 2002). They are also important intermediates in the synthesis of many complex natural products (Krishnaiah et al., 2009). Among these compounds, 3-substituted-1,2benzisoxazole and its derivatives are emerging as potential antipsychotic compounds (Kayalvizhi et al., 2011).

Related literature
Substituted benzoxazoles have been reported to possess diverse chemotherapeutic properties including antibiotic, antimicrobial, antiviral, antitumor and other pharmacological activities (Qu et al., 2008;Krishnaiah et al., 2009). With its extensive uses as a drug for epilepsy, its cost-effective synthesis remained a great challenge for synthetic organic chemists (Veerareddy et al., 2011). In a search for new benzisoxazole compounds with better biological activity, the title compound, C 10 H 10 ClNO, was synthesized and its crystal structure determined, in order to examine the structure-activity effects of the chloromethyl and 6,7-dimethyl substituents on the benzoisoxazole ring.

Experimental
To a solution of 3,6,7-trimethylbenzo[d]isoxazole-2-oxide (1.0 mol) in methylene dichloride (10 ml) was added POCl 3 (2.0 mol) dropwise at 20°C over a period of 5 min and stirred for 5 min also at 20°C. Triethylamine (2.0 mol) was then added dropwise at 20°C over a period of 10 min at such a rate that the reaction temperature did not exceed 30°C. The mixture was then stirred at reflux temperature for 48 h and cooled to 10°C. The reaction mixture was washed with chilled water, followed by addition of a 10% Na 2 CO 3 solution to obtain a neutral pH. The aqueous layer was re-extracted with methylene chloride (2 × 100 ml). The combined organic layer was dried over anhydrous Na 2 SO 4 and the solvent was removed under vacuum to give the crude product, which was purified by column chromatography and by crystallization

Refinement
All the H atoms were positioned geometrically and treated as riding on their parent atoms, with C-H = 0.93 Å (aromatic), 0.96 Å (methyl) and 0.97 Å (methylene), and refined using a riding model with U iso (H) = 1.2U eq or 1.5U eq (parent atom).   The crystal packing of the title compound in the unit cell, viewed down the b axis, showing the molecular dimers. Hydrogen site location: inferred from neighbouring sites H-atom parameters constrained w = 1/[σ 2 (F o 2 ) + (0.0575P) 2 + 1. 2791P] where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.25 e Å −3 Δρ min = −0.19 e Å −3 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq