Crystal structure of 1-(5-bromo-1-benzo­furan-2-yl)ethanone oxime

The title compound, C₁₀H₈BrNO₂, is almost planar (r.m.s. deviation for the non-H atoms = 0.031 Å) and the conformation across the C=N bond is trans. Further, the O atom of the benzo­furan ring is syn to the N atom of the oxime group. In the crystal, inversion dimers linked by pairs of O—H⋯N hydrogen bonds generate R₂²(6) loops. Very weak aromatic π–π stacking inter­actions [centroid–centroid separations = 3.9100 (12) and 3.9447 (12) Å] are also observed.

1. Related literature

For the various biological activities of the benzo­furan moiety, see: Rida et al. (2006); Manna et al. (2010); Patil et al. (2010); Patel et al. (2006). For the anti­fungal activity of (benzo­furan-2-yl) keoximes, see: Demirayak et al. (2002). For related structures, see: Aruna Kumar et al. (2014).

2. Experimental

2.1. Crystal data

• C₁₀H₈BrNO₂

• M_r = 254.08

• Monoclinic, P 2₁ /n

• a = 5.9548 (6) Å

• b = 9.4897 (10) Å

• c = 17.2906 (19) Å

• β = 96.943 (6)°

• V = 969.91 (18) ų

• Z = 4

• Mo Kα radiation

• μ = 4.21 mm⁻¹

• T = 296 K

• 0.32 × 0.25 × 0.21 mm

2.2. Data collection

• Bruker APEXII diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2009) T_min = 0.294, T_max = 0.413

• 10152 measured reflections

• 2766 independent reflections

• 1937 reflections with I > 2σ(I)

• R_int = 0.023

2.3. Refinement

• R[F² > 2σ(F²)] = 0.033

• wR(F²) = 0.096

• S = 1.01

• 2766 reflections

• 129 parameters

• H-atom parameters constrained

• Δρ_max = 0.29 e Å⁻³

• Δρ_min = −0.33 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯N1^i	0.82	2.13	2.808 (2)	140
Symmetry code: (i) -x+2, -y-1, -z.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT-Plus (Bruker, 2009); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Chemical context

The literature indicates that compounds having benzo­furan nucleus possesses versatile pharmacological activities like anifungal, anti­arrythmic, uricisuric, vasodilator and anti­migraine agent (Rida et al., 2006; Manna et al., 2010; Patil et al., 2010; Patel et al., 2006). Further, (Benzo­furan-2-yl) keoxime derivatives are known to show good anti­fungal activities (Demirayak et al., 2002). In view of the above and in continuation of our efforts to study the crystal structures of benzo­furan moities (Aruna Kumar et al., 2014), the title compound was synthesized and its crystal structure was determined.

S2. Structural commentary

The title compound (I), C₁₀H₈BrNO₂, is almost planar (r.m.s. deviation for the non-H atoms = 0.031 Å) and the conformation across the C=N bond is trans in (I) (Figure 1). In contrast to this, the conformation across the C=N bond is syn in (1Z)-1-(1-Benzo­furan-2-yl)ethanone oxime (II) (Aruna Kumar et al., 2014). Further, the O atom of the benzo­furan ring is trans to the CH₃ group in the side chain of (I), where as, in (II) (Aruna Kumar et al., 2014), it is syn. The torsions in the side chain of (I) have values: O1—C8—C9—N1 = 3.3 (3)^o, C8—C9—N1—O2 = 179.41 (17)^o and C7—C8—C9—C10 = 3.9 (4)^o. The corresponding torsions in (II) have values 177.02 (16)^o, 0.6 (3)^o and 178.2 (2)^o respectively (Aruna Kumar et al., 2014).

S3. Supra­molecular features

The crystal structure features strong O2—H2A···N1 hydrogen bonds leading into R₂²(6) dimers, and these dimers are further inter­connected via two π···π inter­actions, namely cg1···cg1 and cg1···cg2 (where cg1 is the centroid of the furan ring C4/C5/C7/C8/O1 and cg2 is the centroid of the aryl ring C1—C6) (Figure 2, Table 2), the centroid-centroid separations being 3.9447 (12) Å and 3.9100 (12) Å respectively.

S4. Synthesis and crystallization

5-bromo-2-acetyl­benzo­furan (1 g, 0.0062 mmol), hydroxyl­amine hydro­chloride (0.65 g, 0.0093 mmol) and anhydrous K₂CO₃ (1.29 g, 0.0093 mmol) were taken in EtOH: H₂O (3:1, 10 mL) and refluxed for 3 h. After the completion of the reaction, the reaction mixture was poured into ice cold water. The separated white solid was filtered, washed with water and dried. It was recrystallized from EtOH.

Colourless prisms were obtained from the solvent system: ethyl acetate: methanol (4:1) by slow evapouration technique.

S5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The H atoms were positioned with idealized geometry using a riding model with C—H = 0.93–0.96 Å and O—H = 0.82 Å. The isotropic displacement parametersfor all H atoms were set to 1.2 times Ueq(Caromatic) and 1.5 times Ueq(Cmethyl, O).

Related literature

For the various biological activities of the benzofuran moiety, see: Rida et al. (2006); Manna et al. (2010); Patil et al. (2010); Patel et al. (2006). For the antifungal activity of (benzofuran-2-yl) keoximes, see: Demirayak et al. (2002). For related structures, see: Aruna Kumar et al. (2014).

Computing details

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT-Plus (Bruker, 2009); data reduction: SAINT-Plus (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. Molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. Crystal packing of the title compound displaying O—H···N and π–π interactions.

1-(5-Bromo-1-benzofuran-2-yl)ethanone oxime

Crystal data

C10H8BrNO2	F(000) = 504
Mr = 254.08	Prism
Monoclinic, P21/n	Dx = 1.740 Mg m^−3
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 5.9548 (6) Å	Cell parameters from 125 reflections
b = 9.4897 (10) Å	θ = 3.5–29.9°
c = 17.2906 (19) Å	µ = 4.21 mm^−1
β = 96.943 (6)°	T = 296 K
V = 969.91 (18) Å^3	Prism, colourless
Z = 4	0.32 × 0.25 × 0.21 mm

Data collection

Bruker APEXII diffractometer	1937 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.023
Graphite monochromator	θmax = 29.9°, θmin = 3.5°
phi and φ scans	h = −8→7
Absorption correction: multi-scan (SADABS; Bruker, 2009)	k = −13→10
Tmin = 0.294, Tmax = 0.413	l = −18→24
10152 measured reflections	1 standard reflections every 2 reflections
2766 independent reflections	intensity decay: 0.5%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.096	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0563P)^2 + 0.0157P] where P = (Fo^2 + 2Fc^2)/3
2766 reflections	(Δ/σ)max = 0.001
129 parameters	Δρmax = 0.29 e Å^−3
0 restraints	Δρmin = −0.33 e Å^−3

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
C8	0.5278 (3)	−0.2686 (2)	−0.00305 (11)	0.0391 (4)
C1	0.3056 (3)	0.0480 (2)	0.16815 (12)	0.0447 (5)
C2	0.5215 (3)	0.0179 (2)	0.20434 (11)	0.0492 (5)
H2	0.5745	0.0626	0.2509	0.059*
C3	0.6569 (3)	−0.0767 (2)	0.17233 (12)	0.0492 (5)
H3	0.8014	−0.0979	0.1961	0.059*
C4	0.5691 (3)	−0.1394 (2)	0.10298 (11)	0.0390 (4)
C5	0.3543 (3)	−0.1120 (2)	0.06601 (11)	0.0403 (4)
C6	0.2169 (3)	−0.0159 (2)	0.09927 (12)	0.0470 (5)
H6	0.0714	0.0043	0.0761	0.056*
C7	0.3324 (3)	−0.1982 (2)	−0.00278 (12)	0.0437 (5)
H7	0.2065	−0.2041	−0.0401	0.052*
C9	0.6021 (3)	−0.3724 (2)	−0.05598 (11)	0.0412 (4)
C10	0.4500 (4)	−0.4102 (3)	−0.12802 (12)	0.0513 (5)
H10A	0.4955	−0.3594	−0.1716	0.077*
H10B	0.2969	−0.3859	−0.1215	0.077*
H10C	0.4598	−0.5096	−0.1373	0.077*
N1	0.7969 (3)	−0.42793 (19)	−0.03532 (10)	0.0445 (4)
O1	0.6789 (2)	−0.23533 (16)	0.06169 (8)	0.0440 (3)
O2	0.8582 (2)	−0.52765 (17)	−0.08799 (9)	0.0548 (4)
H2A	0.9720	−0.5695	−0.0688	0.082*
Br1	0.13019 (4)	0.18428 (3)	0.214769 (13)	0.05936 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C8	0.0409 (10)	0.0392 (10)	0.0356 (10)	−0.0021 (8)	−0.0023 (7)	0.0055 (8)
C1	0.0505 (11)	0.0403 (11)	0.0447 (11)	0.0004 (8)	0.0111 (8)	0.0024 (9)
C2	0.0551 (12)	0.0525 (13)	0.0388 (11)	−0.0044 (10)	0.0009 (8)	−0.0040 (9)
C3	0.0452 (10)	0.0586 (14)	0.0412 (11)	−0.0014 (9)	−0.0058 (8)	−0.0012 (10)
C4	0.0362 (9)	0.0410 (11)	0.0394 (10)	−0.0003 (8)	0.0032 (7)	0.0031 (8)
C5	0.0401 (9)	0.0391 (11)	0.0405 (10)	−0.0005 (8)	0.0002 (7)	0.0062 (8)
C6	0.0442 (10)	0.0492 (12)	0.0464 (12)	0.0043 (9)	0.0010 (8)	0.0035 (9)
C7	0.0391 (10)	0.0498 (13)	0.0403 (11)	0.0035 (8)	−0.0037 (8)	−0.0002 (9)
C9	0.0429 (10)	0.0416 (11)	0.0384 (10)	−0.0034 (8)	0.0028 (8)	0.0051 (9)
C10	0.0520 (11)	0.0552 (14)	0.0444 (12)	0.0022 (10)	−0.0030 (9)	−0.0011 (10)
N1	0.0447 (9)	0.0462 (10)	0.0420 (9)	0.0057 (7)	0.0028 (7)	−0.0024 (7)
O1	0.0379 (7)	0.0496 (8)	0.0420 (7)	0.0041 (6)	−0.0052 (5)	−0.0014 (6)
O2	0.0562 (9)	0.0591 (10)	0.0493 (8)	0.0142 (7)	0.0066 (6)	−0.0069 (7)
Br1	0.0661 (2)	0.05433 (19)	0.06028 (19)	0.00532 (9)	0.01851 (12)	−0.00638 (10)

Geometric parameters (Å, º)

C8—C7	1.343 (3)	C5—C6	1.394 (3)
C8—O1	1.385 (2)	C5—C7	1.437 (3)
C8—C9	1.449 (3)	C6—H6	0.9300
C1—C6	1.383 (3)	C7—H7	0.9300
C1—C2	1.390 (3)	C9—N1	1.285 (3)
C1—Br1	1.901 (2)	C9—C10	1.493 (3)
C2—C3	1.367 (3)	C10—H10A	0.9600
C2—H2	0.9300	C10—H10B	0.9600
C3—C4	1.383 (3)	C10—H10C	0.9600
C3—H3	0.9300	N1—O2	1.392 (2)
C4—O1	1.371 (2)	O2—H2A	0.8200
C4—C5	1.384 (2)
C7—C8—O1	111.24 (18)	C1—C6—C5	117.40 (17)
C7—C8—C9	132.16 (16)	C1—C6—H6	121.3
O1—C8—C9	116.56 (17)	C5—C6—H6	121.3
C6—C1—C2	122.23 (19)	C8—C7—C5	107.11 (16)
C6—C1—Br1	119.44 (15)	C8—C7—H7	126.4
C2—C1—Br1	118.33 (15)	C5—C7—H7	126.4
C3—C2—C1	120.75 (18)	N1—C9—C8	115.94 (16)
C3—C2—H2	119.6	N1—C9—C10	124.7 (2)
C1—C2—H2	119.6	C8—C9—C10	119.31 (17)
C2—C3—C4	117.00 (18)	C9—C10—H10A	109.5
C2—C3—H3	121.5	C9—C10—H10B	109.5
C4—C3—H3	121.5	H10A—C10—H10B	109.5
O1—C4—C3	125.70 (16)	C9—C10—H10C	109.5
O1—C4—C5	110.89 (16)	H10A—C10—H10C	109.5
C3—C4—C5	123.4 (2)	H10B—C10—H10C	109.5
C4—C5—C6	119.22 (18)	C9—N1—O2	113.35 (16)
C4—C5—C7	105.18 (17)	C4—O1—C8	105.58 (15)
C6—C5—C7	135.61 (16)	N1—O2—H2A	109.5
C6—C1—C2—C3	0.5 (3)	C9—C8—C7—C5	178.2 (2)
Br1—C1—C2—C3	−178.43 (16)	C4—C5—C7—C8	−0.3 (2)
C1—C2—C3—C4	0.2 (3)	C6—C5—C7—C8	179.5 (2)
C2—C3—C4—O1	179.3 (2)	C7—C8—C9—N1	−174.5 (2)
C2—C3—C4—C5	−0.6 (3)	O1—C8—C9—N1	3.3 (3)
O1—C4—C5—C6	−179.65 (18)	C7—C8—C9—C10	3.9 (4)
C3—C4—C5—C6	0.3 (3)	O1—C8—C9—C10	−178.38 (19)
O1—C4—C5—C7	0.2 (2)	C8—C9—N1—O2	179.41 (17)
C3—C4—C5—C7	−179.9 (2)	C10—C9—N1—O2	1.1 (3)
C2—C1—C6—C5	−0.9 (3)	C3—C4—O1—C8	−179.9 (2)
Br1—C1—C6—C5	178.09 (15)	C5—C4—O1—C8	0.0 (2)
C4—C5—C6—C1	0.4 (3)	C7—C8—O1—C4	−0.3 (2)
C7—C5—C6—C1	−179.3 (2)	C9—C8—O1—C4	−178.48 (16)
O1—C8—C7—C5	0.4 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···N1^i	0.82	2.13	2.808 (2)	140

Symmetry code: (i) −x+2, −y−1, −z.

 

Footnotes

‡These authors contributed equally.