3-Benzyl-5-methyl-1,2-benzoxazole 2-oxide

G Anuradha; Vasuki Gopalsamy; A Veera Reddy; G Laxminarasimhulu

doi:10.1107/S160053681203838X

. 2012 Sep 19;68(Pt 10):o2957. doi: 10.1107/S160053681203838X

3-Benzyl-5-methyl-1,2-benzoxazole 2-oxide

G Anuradha ^a, Vasuki Gopalsamy ^a,^*, A Veera Reddy ^b, G Laxminarasimhulu ^b

PMCID: PMC3470327 PMID: 23125740

Abstract

In the title compound, C₁₅H₁₃NO₂, the isoxazole unit and the attached benzene ring are almost coplanar, making a dihedral angle of 1.42 (8)°. The benzyl ring is inclined to the isoxazole ring by 74.19 (8)° and is in a +sc conformation with respect to the benzisoxazole unit. In the crystal, C—H⋯O hydrogen bonds link the molecules, forming zigzag chains propagating along the b axis. There are also π–π interactions present involving the isoxazole and benzyl rings [centroid–centroid distance = 3.5209 (10) Å], and C—H⋯π interactions involving the benzene ring of the benzoisoxazole unit and the methylene bridging group.

Related literature

For the anti-epileptic, antispasmodic and antifungal properties of benzoxazole derivatives, see: Jian et al. (2007 ▶). For their antituberculer activity, see: Vinšová et al. (2007 ▶). For other biological activties of isoxazoles and benzisoxazole derivatives, see: Veera Reddy et al. (2011 ▶). For details of the synthesis, see: Veera Reddy et al. (2011 ▶). For the related structure 5-chloro-3-methyl-1,2-benzisoxazole-2-oxide, see: Ghari & Viterbo (1982 ▶).

Experimental

Crystal data

C₁₅H₁₃NO₂
M _r = 239.26
Monoclinic,
a = 6.4527 (2) Å
b = 11.2213 (4) Å
c = 16.9371 (7) Å
β = 100.002 (2)°
V = 1207.74 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1999 ▶) T _min = 0.974, T _max = 0.983
13491 measured reflections
3512 independent reflections
2113 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.172
S = 1.06
3512 reflections
163 parameters
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT-Plus (Bruker, 2004 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S160053681203838X/su2493sup1.cif

e-68-o2957-sup1.cif^{(17.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681203838X/su2493Isup2.hkl

e-68-o2957-Isup2.hkl^{(172.3KB, hkl)}

Supplementary material file. DOI: 10.1107/S160053681203838X/su2493Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg2 is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5⋯O2ⁱ	0.93	2.49	3.154 (2)	128
C8—H8B⋯Cg2ⁱⁱ	0.97	3.00	3.6800 (16)	129

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The authors thank the Sophisticated Analytical Instrument Facility, IIT-Madras, Chennai-36, for the data collection.

supplementary crystallographic information

Comment

Isoxazoles and benzisoxazoles are important classes of nitrogen-oxygen containing heterocycles. They have extensive biological applications and are useful intermediates in medicinal chemistry (Veera Reddy et al., 2011). The benzoxazole skeleton is an essential structural unit of several antibacterial, anticancer and anti-HIV-1 agents. The antituberculotic activity of several benzoxazole derivatives have been reported (Vinšová et al., 2007). Some benzoxazoles exhibit high fluorescence and are used as optical whitening agents, photoluminesents and active components in dye lasers. Benzoxazole derivatives show antiepileptic, antispasmodic and antifungal properties (Jian et al., 2007). 3-substituted 1,2-benzisoxazole derivatives are emerging as potential antipsychotic compounds, antiseizure agents and are also used to block the repetitive firing of voltage-sensitive sodium channels and so reduce voltage-sensitive T-type calcium currents (Veera Reddy et al., 2011).

The molecular structure of the title functionalized 1,2-benzisoxazole compound is illustrated in Fig. 1. It contains three planar rings, namely, a methyl substituted benzene ring A = C2—C7, an isoxazole ring B =C1/C7/C6/O1/N1 and the benzyl ring C = C9—C14. The dihedral angles between rings A/B and B/C are 1.42 (8)° and 74.19 (8)°, respectively.

The bond lengths and angles in the title compound are in good agreement with the expected values and are comparable with the corresponding values reported for 5-chloro-3-methyl-1,2-benzisoxazole-2-oxide (Ghari & Viterbo, 1982).

In the crystal, molecules are linked via C—H···O hydrogen bonds leading to the formation of zigzag chains propagating along the a axis direction (Tabel 1 and Fig. 2). Molecules are also linked via C—H···π (Table 1) and π···π interactions. The latter involve the isoxazole (B = Cg1) and benzyl rings (C = Cg3) [Cg1···Cg3ⁱ = 3.5209 (10) Å; symmetry code: (i) -x + 1.5, y - 1/2, -z + 1/2].

Experimental

The compound was synthesized by the published method (Veera Reddy et al., 2011)