6-Chloro-2H-1,4-benzoxazin-3(4H)-one

Abstract

In the title compound, C₈H₆ClNO₂, the conformation of the six-membered heterocyclic ring is close to screw boat and the mol­ecules are linked via inter­molecular N—H⋯O hydrogen bonds along the b axis.

Related literature

For biological activities of 1,4-benzoxazin-3(4H)-one derivatives, see: Huang et al. (2005 ▶); Macchiarulo et al. (2002 ▶). For a related structure, see: Pang et al. (2006 ▶).

Experimental

Crystal data

• C₈H₆ClNO₂

• M _r = 183.59

• Orthorhombic,

• a = 4.5359 (6) Å

• b = 7.700 (1) Å

• c = 21.281 (3) Å

• V = 743.28 (17) ų

• Z = 4

• Mo Kα radiation

• μ = 0.46 mm⁻¹

• T = 273 (2) K

• 0.12 × 0.10 × 0.06 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2002 ▶) T _min = 0.878, T _max = 0.973

• 3857 measured reflections

• 1314 independent reflections

• 1143 reflections with I > 2σ(I)

• R _int = 0.047

Refinement

• R[F ² > 2σ(F ²)] = 0.038

• wR(F ²) = 0.088

• S = 1.07

• 1314 reflections

• 109 parameters

• H-atom parameters constrained

• Δρ_max = 0.16 e Å⁻³

• Δρ_min = −0.21 e Å⁻³

• Absolute structure: Flack (1983 ▶), 500 Friedel pairs

• Flack parameter: 0.06 (11)

Data collection: SMART (Bruker 2002 ▶); cell refinement: SAINT (Bruker 2002 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: XP in SHELXTL (Sheldrick 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1i	0.86	2.00	2.844 (3)	166

Symmetry code: (i) .

supplementary crystallographic information

Comment

Benzo[1,4]oxazin-3(4H)-one derivatives are one of the important classes of heterocyclic compounds and have been shown to exhibit a wide range of biological activities such as herbicidal (Huang et al., 2005) and antifungal (Macchiarulo et al., 2002). We report here the crystal structure of 6-chloro-2H-benzo[b][1,4]oxazin-3(4H)-one.

The molecular structure is illustrated in Fig. 1. The conformation of the six-membered heterocyclic ring is close to screw boat, with atoms C1 and C2 out of the plane of the remaining four atoms by 0.301 (5) and 0.635 (5) Å, respectively. In a related compound containing the benzo[1,4]oxazin-3(4H)-one system (Pang et al., 2006), the heterocyclic ring also adopts a screw boat conformation. The molecules are connected via N - H ··· O hydrogen bonding into chains along the b axis.

Experimental

To a 25 ml round-bottomed flask equipped with a reflux condenser were added 2-chloro-N-(5-chloro-2-hydroxyphenyl)acetamide (2.19 g, 10 mmol), potassium carbonate (2.76 g, 20 mmol) and anhydrous DMF (20 ml). The resulting mixture was heated under reflux for 90 min. After this time, the reaction mixture was poured into 80 g of water, and stirred for 15 min. The mixture was extracted with ethyl acetate (2 x 20 ml). The ethyl acetate extract was washed with saturated brine (10 ml). After drying over Na₂SO₄, the solvent was removed under vacuum and a colourless solid was obtained in 80% yield (1.46 g). Suitable crystals were grown by evaporation of a CH₂Cl₂ solution at room temperature for 4 d.

Refinement

All H atoms were positioned geometrically (N - H = 0.86 Å, aromatic C - H = 0.93 Å, methylene C - H = 0.97 Å) and refined using a riding model; U_iso(H) = 1.2 U_eq(C, N).

Figures

Fig. 1.

The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.

Crystal data

C8H6ClNO2	Dx = 1.641 Mg m−3
Mr = 183.59	Mo Kα radiation λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 1287 reflections
a = 4.5359 (6) Å	θ = 3.3–24.4º
b = 7.700 (1) Å	µ = 0.46 mm−1
c = 21.281 (3) Å	T = 273 (2) K
V = 743.28 (17) Å3	Plate, colourless
Z = 4	0.12 × 0.10 × 0.06 mm
F000 = 376

Data collection

Bruker SMART CCD area-detector diffractometer	1314 independent reflections
Radiation source: fine-focus sealed tube	1143 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.047
T = 273(2) K	θmax = 25.0º
φ and ω scans	θmin = 1.9º
Absorption correction: multi-scan(SADABS; Bruker, 2002)	h = −5→4
Tmin = 0.878, Tmax = 0.973	k = −8→9
3857 measured reflections	l = −25→23

Refinement

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.038	w = 1/[σ2(Fo2) + (0.0401P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.088	(Δ/σ)max < 0.001
S = 1.07	Δρmax = 0.16 e Å−3
1314 reflections	Δρmin = −0.20 e Å−3
109 parameters	Extinction correction: none
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 500 Friedel pairs
Secondary atom site location: difference Fourier map	Flack parameter: 0.06 (11)

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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 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 (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.59509 (18)	0.16633 (10)	0.92672 (4)	0.0538 (3)
O1	1.5486 (5)	0.7552 (2)	0.74891 (10)	0.0488 (6)
O2	1.1177 (4)	0.8424 (2)	0.88354 (9)	0.0466 (6)
N1	1.2830 (5)	0.5732 (3)	0.80882 (10)	0.0347 (6)
H1	1.3651	0.4842	0.7918	0.042*
C1	1.3640 (6)	0.7302 (3)	0.79030 (14)	0.0350 (7)
C2	1.2111 (7)	0.8777 (3)	0.82142 (15)	0.0448 (8)
H2A	1.3430	0.9768	0.8222	0.054*
H2B	1.0404	0.9094	0.7965	0.054*
C3	0.9870 (6)	0.6859 (3)	0.89160 (13)	0.0346 (7)
C4	1.0683 (6)	0.5467 (3)	0.85521 (12)	0.0295 (6)
C5	0.9496 (6)	0.3866 (3)	0.86535 (13)	0.0339 (6)
H5	1.0043	0.2924	0.8406	0.041*
C6	0.7466 (6)	0.3675 (3)	0.91299 (13)	0.0369 (7)
C7	0.6661 (6)	0.5045 (4)	0.94990 (13)	0.0408 (7)
H7	0.5317	0.4889	0.9824	0.049*
C8	0.7839 (6)	0.6642 (4)	0.93876 (13)	0.0402 (7)
H8	0.7267	0.7586	0.9631	0.048*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cl1	0.0588 (5)	0.0489 (4)	0.0537 (5)	−0.0086 (4)	0.0042 (4)	0.0129 (4)
O1	0.0582 (14)	0.0464 (11)	0.0420 (13)	−0.0049 (10)	0.0170 (12)	0.0038 (9)
O2	0.0600 (14)	0.0389 (10)	0.0410 (13)	−0.0064 (12)	0.0119 (11)	−0.0098 (9)
N1	0.0375 (13)	0.0348 (12)	0.0319 (14)	0.0014 (11)	0.0068 (11)	−0.0017 (10)
C1	0.0401 (17)	0.0378 (14)	0.0272 (16)	−0.0022 (13)	−0.0029 (14)	−0.0005 (12)
C2	0.0532 (19)	0.0390 (15)	0.0423 (19)	−0.0032 (14)	0.0061 (16)	0.0019 (14)
C3	0.0362 (16)	0.0372 (14)	0.0305 (16)	−0.0012 (13)	−0.0001 (12)	−0.0028 (12)
C4	0.0291 (14)	0.0372 (14)	0.0221 (14)	0.0016 (13)	0.0002 (13)	−0.0008 (11)
C5	0.0370 (15)	0.0365 (14)	0.0282 (15)	0.0021 (13)	−0.0049 (13)	−0.0006 (11)
C6	0.0357 (15)	0.0424 (15)	0.0327 (17)	−0.0011 (13)	−0.0026 (13)	0.0083 (13)
C7	0.0392 (18)	0.0534 (17)	0.0297 (17)	−0.0007 (15)	0.0057 (13)	0.0011 (15)
C8	0.0425 (16)	0.0464 (15)	0.0315 (17)	0.0058 (16)	0.0041 (13)	−0.0052 (14)

Geometric parameters (Å, °)

Cl1—C6	1.720 (3)	C3—C8	1.373 (4)
O1—C1	1.231 (3)	C3—C4	1.373 (4)
O2—C3	1.354 (3)	C4—C5	1.362 (4)
O2—C2	1.414 (4)	C5—C6	1.377 (4)
N1—C1	1.324 (3)	C5—H5	0.9300
N1—C4	1.402 (3)	C6—C7	1.365 (4)
N1—H1	0.8600	C7—C8	1.362 (4)
C1—C2	1.486 (4)	C7—H7	0.9300
C2—H2A	0.9700	C8—H8	0.9300
C2—H2B	0.9700
C3—O2—C2	114.9 (2)	C5—C4—C3	120.7 (3)
C1—N1—C4	122.4 (2)	C5—C4—N1	121.2 (2)
C1—N1—H1	118.8	C3—C4—N1	118.0 (2)
C4—N1—H1	118.8	C4—C5—C6	118.5 (3)
O1—C1—N1	123.0 (3)	C4—C5—H5	120.7
O1—C1—C2	121.1 (2)	C6—C5—H5	120.7
N1—C1—C2	115.8 (3)	C7—C6—C5	121.3 (3)
O2—C2—C1	114.2 (2)	C7—C6—Cl1	119.4 (2)
O2—C2—H2A	108.7	C5—C6—Cl1	119.2 (2)
C1—C2—H2A	108.7	C8—C7—C6	119.5 (3)
O2—C2—H2B	108.7	C8—C7—H7	120.2
C1—C2—H2B	108.7	C6—C7—H7	120.2
H2A—C2—H2B	107.6	C7—C8—C3	120.1 (3)
O2—C3—C8	119.7 (2)	C7—C8—H8	120.0
O2—C3—C4	120.4 (2)	C3—C8—H8	120.0
C8—C3—C4	119.8 (3)
C4—N1—C1—O1	−178.8 (2)	C1—N1—C4—C5	167.7 (3)
C4—N1—C1—C2	−0.5 (4)	C1—N1—C4—C3	−14.2 (4)
C3—O2—C2—C1	−44.4 (3)	C3—C4—C5—C6	−0.1 (4)
O1—C1—C2—O2	−152.3 (3)	N1—C4—C5—C6	177.9 (2)
N1—C1—C2—O2	29.4 (4)	C4—C5—C6—C7	−0.5 (4)
C2—O2—C3—C8	−152.6 (3)	C4—C5—C6—Cl1	−179.8 (2)
C2—O2—C3—C4	31.1 (3)	C5—C6—C7—C8	1.3 (4)
O2—C3—C4—C5	176.3 (3)	Cl1—C6—C7—C8	−179.4 (2)
C8—C3—C4—C5	0.0 (4)	C6—C7—C8—C3	−1.4 (4)
O2—C3—C4—N1	−1.7 (4)	O2—C3—C8—C7	−175.6 (2)
C8—C3—C4—N1	−178.1 (2)	C4—C3—C8—C7	0.8 (4)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1i	0.86	2.00	2.844 (3)	166

Symmetry codes: (i) −x+3, y−1/2, −z+3/2.