1-(1-Benzofuran-2-yl)-2-chloro­ethanone

The title compound, C₁₀H₇ClO₂, was synthesized from 1-benzofuran-2-ylethanone by chlorination with thionyl chloride. The benzofuran ring system and the carbonyl group are coplanar. The carbonyl group is in a syn position relative to both the O atom of the benzofuran ring and the Cl atom. C—H...O contacts are found between the methyl­ene group and carbonyl O atom. Mol­ecules related by a centre of symmetry are involved in π–π inter­actions, with distances between the centroids of the furan rings of 3.785 (3) Å.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.086
• wR factor = 0.165
• Data-to-parameter ratio = 23.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT127_ALERT_1_C Implicit Hall Symbol  Inconsistent with Explicit    P2ac2ab

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Aryl-2-chloroethanone and alkyl-2-chloroethanons are precursors of appropriate beta-amino-alfa-aryl (or alkyl) ethanols (Zaidlewicz et al., 2005; Tanis et al., 2006). These compounds containing the amino function exhibit the pharmacological activity. Many beta-amine arylethanol derivatives such as albuterol, isoproterenol, sotalol and terbutaline are well known beta-blockers or agonists and used in treatment of asthma, glaucoma, and cardiovascular disease (Gareth, 2001). All of them are nonselective beta-adrenoreceptor blocking agents comparable to propranolol (Weerawarna et al., 1991; Fothergill et al., 1977). Aromatic beta-aminoalcohols are also widely used as substrates in studies of the oxidation in liver by cytochrome P450 enzymes (Narimatsu et al., 2003). Furthermore, many compounds mentioned above show an anti-arrythmic properties. Developing methods of their enantioselective synthesis is of particular importance.

We have found that crystal structure of the title compound is not known yet, although it is a well known substrate for the synthesis of benzofuran derivatives revealing different biological activity. Therefore, the aim of the study was to determine its molecular and crystal structures.

The molecule is planar with the dihedral angle of 1.9 (2) ^o between the best planes of benzofuran ring system and C2—C8—O2—C9 group containing carbonyl moiety. The chloromethylene moiety is almost co-planar with the ring system: the C2—C8—C9—Cl1 torsion angle is -175.8 (2) ^o, with the r.m.s. deviation of Cl1 from that plane of 0.079 (4) Å. The carbonyl O2 is in syn position relative to benzofuran O1, the O1—C2—C8—O2 torsion angle is 1.6 (4) ^o. The chlorine atom is positioned in syn orientation relative to carbonyl O2, with the O2—C8—C9—Cl1 torsion angle 4.7 (4) ^o. The valence geometry of the investigated compound is similar to that found for unsubstitituted compounds at position 3. In the reported structure the O1—C2 distance is 1.385 (3) Å and it is similar to 1.385 Å found in 2-acetylbenzo(b)furan (Thiruvalluvar et al., 2003). However, the substituted compounds: [2-acetyl-3-(benzoylamino)-1-benzofuran (Ocak Ískeleli et al., 2005), 2-acetyl-3-aminobenzofuran (Bachechi et al., 1988), and 1-(3-amino-1-benzofuran-2-yl)-2-mesitylethanone (Arıcı et al., 2004) reveal somewhat longer bond distances of 1.403–1.411 Å.

The packing analysis revealed that each molecule forms a pair of intermolecular C—H···O contact of 3.238 (3) Å along the b axis involving its C9—H methylene group and carbonyl oxygen, the C9···O2 (0.5 - x, 1/2 + y, z). The packing interactions are completed by stacking of the ring systems of the molecules related by a centre of inversion (1 - x, 1 - y, -z). Interaction π···π between adjacent molecules is characterized by distance between centroids of the furane moieties of 3.785 (3) Å. In these dimers anti-parallel orientation of molecules occurs.

Related literature

For related literature, see: Arıcı et al. (2004); Bachechi et al. (1988); Fothergill et al. (1977); Gareth (2001); Ocak Ískeleli et al. (2005); Narimatsu et al. (2003); Tanis et al. (2006); Thiruvalluvar et al. (2003); Weerawarna et al. (1991); Zaidlewicz et al. (2005).

S2. Experimental

The title compound, 1-(benzofuran-2-yl)-2-chloroethanone, was synthesized from 1-benzofuran-2-ylethanone by chlorination with thionyl chloride in the carbon tetrachloride solution. Crystals suitable for the diffraction experiment were obtained by slow evaporation from the ethanol solution. Structure was solved with the direct methods and refined using SHELX98 package (Sheldrick, 1997).

S3. Refinement

Hydrogen atoms were put in the calculated positions and constrained during refinement (C—H 0.98 Å, aromatic C—H 0.93 Å, U fixed at 0.080 Ų).

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2000); cell refinement: CrysAlis RED or CCD? (Oxford Diffraction, 2000); data reduction: CrysAlis RED (Oxford Diffraction, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: CIFTAB in SHELXL97.

Figures

Fig. 1. A view of (I) with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

1-(1-Benzofuran-2-yl)-2-chloroethanone

Crystal data

C10H7ClO2	F(000) = 800
Mr = 194.61	Dx = 1.485 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P2ac2ab	Cell parameters from 2172 reflections
a = 9.550 (2) Å	θ = 3.1–31.4°
b = 10.303 (2) Å	µ = 0.40 mm^−1
c = 17.695 (4) Å	T = 293 K
V = 1741.1 (6) Å^3	Plate, colorless
Z = 8	0.34 × 0.14 × 0.08 mm

Data collection

Oxford Diffraction Sapphire CCD diffractometer	2726 independent reflections
Radiation source: fine-focus sealed tube	1768 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.074
θ/2θ scans	θmax = 31.4°, θmin = 3.1°
Absorption correction: numerical (CrysAlis RED; Oxford Diffraction, 2000)	h = −13→13
Tmin = 0.876, Tmax = 0.968	k = −14→13
16159 measured reflections	l = −25→23

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)] = 0.086	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.165	H-atom parameters constrained
S = 1.24	w = 1/[σ^2(Fo^2) + (0.0534P)^2] where P = (Fo^2 + 2Fc^2)/3
2726 reflections	(Δ/σ)max = 0.003
118 parameters	Δρmax = 0.28 e Å^−3
0 restraints	Δρmin = −0.26 e Å^−3

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
C2	0.3196 (3)	0.4735 (2)	−0.04559 (15)	0.0381 (6)
O1	0.3670 (2)	0.35910 (16)	−0.07774 (10)	0.0438 (5)
C3	0.3858 (3)	0.5771 (2)	−0.07517 (15)	0.0397 (6)
H2A	0.3715	0.6636	−0.0623	0.048*
C3A	0.4825 (3)	0.5288 (3)	−0.13015 (15)	0.0394 (6)
C4	0.5801 (3)	0.5831 (3)	−0.17913 (16)	0.0512 (8)
H4A	0.5930	0.6726	−0.1811	0.061*
C5	0.6573 (3)	0.5017 (3)	−0.22456 (17)	0.0556 (8)
H5A	0.7237	0.5364	−0.2573	0.067*
C6	0.6373 (3)	0.3680 (3)	−0.22217 (17)	0.0552 (8)
H6A	0.6900	0.3153	−0.2540	0.066*
C7	0.5418 (3)	0.3114 (3)	−0.17416 (16)	0.0499 (7)
H7A	0.5291	0.2220	−0.1722	0.060*
C7A	0.4662 (3)	0.3948 (3)	−0.12934 (14)	0.0395 (6)
O2	0.1674 (2)	0.35466 (18)	0.03153 (11)	0.0526 (6)
C8	0.2114 (3)	0.4601 (2)	0.01174 (15)	0.0393 (6)
C9	0.1580 (3)	0.5860 (3)	0.04366 (17)	0.0456 (7)
H9A	0.1140	0.6356	0.0036	0.055*
H9B	0.2365	0.6362	0.0626	0.055*
Cl1	0.03617 (8)	0.56222 (7)	0.11742 (4)	0.0546 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C2	0.0427 (15)	0.0291 (13)	0.0425 (15)	0.0002 (11)	−0.0063 (12)	−0.0020 (12)
O1	0.0514 (12)	0.0303 (10)	0.0497 (12)	0.0004 (8)	0.0019 (9)	−0.0016 (9)
C3	0.0428 (16)	0.0306 (13)	0.0456 (16)	0.0018 (11)	−0.0027 (13)	−0.0018 (12)
C3A	0.0404 (16)	0.0355 (14)	0.0422 (16)	0.0013 (11)	−0.0085 (12)	0.0007 (12)
C4	0.056 (2)	0.0460 (17)	0.0511 (18)	−0.0035 (14)	0.0006 (15)	0.0045 (14)
C5	0.052 (2)	0.068 (2)	0.0468 (18)	0.0014 (15)	0.0039 (15)	0.0052 (16)
C6	0.061 (2)	0.064 (2)	0.0412 (17)	0.0169 (16)	−0.0033 (16)	−0.0043 (16)
C7	0.0599 (19)	0.0405 (16)	0.0494 (17)	0.0079 (14)	−0.0064 (15)	−0.0051 (14)
C7A	0.0426 (16)	0.0373 (14)	0.0387 (15)	0.0014 (12)	−0.0059 (13)	−0.0007 (11)
O2	0.0625 (14)	0.0335 (10)	0.0619 (14)	−0.0017 (9)	0.0071 (10)	0.0069 (10)
C8	0.0419 (16)	0.0326 (14)	0.0432 (15)	0.0005 (12)	−0.0102 (12)	0.0014 (12)
C9	0.0459 (17)	0.0372 (15)	0.0538 (18)	−0.0026 (12)	0.0055 (13)	−0.0012 (13)
Cl1	0.0539 (5)	0.0548 (5)	0.0549 (5)	0.0004 (3)	0.0070 (4)	−0.0025 (4)

Geometric parameters (Å, º)

C2—C3	1.346 (4)	C5—H5A	0.9300
C2—O1	1.385 (3)	C6—C7	1.376 (4)
C2—C8	1.454 (4)	C6—H6A	0.9300
O1—C7A	1.366 (3)	C7—C7A	1.374 (4)
C3—C3A	1.431 (4)	C7—H7A	0.9300
C3—H2A	0.9300	O2—C8	1.216 (3)
C3A—C7A	1.389 (4)	C8—C9	1.504 (4)
C3A—C4	1.391 (4)	C9—Cl1	1.766 (3)
C4—C5	1.376 (4)	C9—H9A	0.9700
C4—H4A	0.9300	C9—H9B	0.9700
C5—C6	1.391 (5)
C3—C2—O1	111.2 (2)	C7—C6—H6A	119.0
C3—C2—C8	132.9 (2)	C5—C6—H6A	119.0
O1—C2—C8	115.9 (2)	C7A—C7—C6	116.1 (3)
C7A—O1—C2	105.79 (19)	C7A—C7—H7A	122.0
C2—C3—C3A	107.0 (2)	C6—C7—H7A	122.0
C2—C3—H2A	126.5	O1—C7A—C7	125.6 (3)
C3A—C3—H2A	126.5	O1—C7A—C3A	110.6 (2)
C7A—C3A—C4	118.8 (3)	C7—C7A—C3A	123.8 (3)
C7A—C3A—C3	105.4 (2)	O2—C8—C2	122.1 (2)
C4—C3A—C3	135.7 (3)	O2—C8—C9	123.0 (3)
C5—C4—C3A	118.5 (3)	C2—C8—C9	114.9 (2)
C5—C4—H4A	120.7	C8—C9—Cl1	112.41 (19)
C3A—C4—H4A	120.7	C8—C9—H9A	109.1
C4—C5—C6	120.8 (3)	Cl1—C9—H9A	109.1
C4—C5—H5A	119.6	C8—C9—H9B	109.1
C6—C5—H5A	119.6	Cl1—C9—H9B	109.1
C7—C6—C5	122.0 (3)	H9A—C9—H9B	107.9
C3—C2—O1—C7A	−0.2 (3)	C6—C7—C7A—O1	−179.7 (2)
C8—C2—O1—C7A	179.8 (2)	C6—C7—C7A—C3A	−0.5 (4)
O1—C2—C3—C3A	0.1 (3)	C4—C3A—C7A—O1	179.6 (2)
C8—C2—C3—C3A	−179.9 (3)	C3—C3A—C7A—O1	−0.2 (3)
C2—C3—C3A—C7A	0.0 (3)	C4—C3A—C7A—C7	0.3 (4)
C2—C3—C3A—C4	−179.7 (3)	C3—C3A—C7A—C7	−179.5 (3)
C7A—C3A—C4—C5	−0.4 (4)	C3—C2—C8—O2	−178.4 (3)
C3—C3A—C4—C5	179.3 (3)	O1—C2—C8—O2	1.6 (4)
C3A—C4—C5—C6	0.7 (4)	C3—C2—C8—C9	2.1 (4)
C4—C5—C6—C7	−0.8 (5)	O1—C2—C8—C9	−177.8 (2)
C5—C6—C7—C7A	0.7 (4)	O2—C8—C9—Cl1	4.7 (4)
C2—O1—C7A—C7	179.5 (3)	C2—C8—C9—Cl1	−175.83 (19)
C2—O1—C7A—C3A	0.2 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C9—H9B···O2^i	0.97	2.49	3.238 (3)	134

Symmetry code: (i) −x+1/2, y+1/2, z.