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Acta Cryst. (2008). E64, o1688    [ doi:10.1107/S1600536808024288 ]

2-(6,7-Dimethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetic acid

H. D. Choi, P. J. Seo, B. W. Son and U. Lee

Abstract top

In the title compound, C13H14O3S, the methyl group of the methylsulfanyl substituent is almost perpendicular to the plane of the benzofuran fragment [80.5 (9)°]. The carboxylic acid groups are involved in intermolecular O-H...O hydrogen bonds, which link the molecules into centrosymmetric dimers. These dimers are further packed into stacks along the a axis by C-H...[pi] interactions.

Comment top

This work is related to our communications on the synthesis and structure of 2-(3-methylsulfanyl-1-benzofuran-2-yl)acetic acid derivatives, viz. 2-(3-methylsulfanyl-5-phenyl-1-benzofuran-2-yl)acetic acid (Choi et al., 2007) and 2-(5-ethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetic acid (Seo et al., 2007). Here we report the crystal structure of the title compound, (I), 2-(6,7-dimethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetic acid (Fig. 1).

The benzofuran unit is essentially planar, with a mean deviation of 0.003 (1) Å from the least-squares plane defined by the nine constituent atoms. In the crystal structure, the carboxyl groups are involved in intermolecular O—H···O hydrogen bonds (Fig. 2 and Table 1; symmetry code as in Fig. 2), which link the molecules into centrosymmetric dimers. These dimers are further packed into stacks along a axis by C—H···π interactions, with a C9—H9A···Cgi separation of 2.86 Å (Fig. 2 and Table 1; Cg is the centroid of the C2—C7 benzene ring, symmetry code as in Fig. 2).

Related literature top

For related structures, see: Choi et al. (2007); Seo et al. (2007). Cg is the centroid of the C2–C7 benzene ring.

Experimental top

Ethyl 2-(6,7-dimethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetate (334 mg, 1.20 mmol) was added to a solution of potassium hydroxide (337 mg, 6.0 mmol) in water (20 ml) and methanol (20 ml), and the mixture was refluxed for 5 h, then cooled. Water was added, and the solution was extracted with dichloromethane. The aqueous layer was acidified to pH = 1 with concentrated hydrochloric acid and then extracted with chloroform, dried over magnesium sulfate, filtered and concentrated under vacuum. The residue was purified by column chromatography (ethyl acetate) to afford the title compound as a colorless solid [yield 84%, m.p. 426–427 K; Rf = 0.63 (ethyl acetate)]. Colorless blocks of (I) were prepared by evaporation of a solution of the title compound in diisopropyl ether at room temperature. Spectroscopic analysis: 1H NMR (CDCl3, 400 MHz) δ 2.32 (s, 3H), 2.38 (s, 3H), 2.40 (s, 3H), 4.04 (s, 2H), 7.10 (d, J = 7.84 Hz, 1H), 7.36 (d, J = 7.84 Hz, 1H), 9.08 (s, 1H); EI—MS 250 [M+].

Refinement top

Atom H3O of the hydroxy group was found in a difference Fourier map and refined freely. The other H atoms were positioned geometrically and refined using a riding model, with C—H = 0.95 Å for aromatic H atoms, 0.99 Å for methylene H atoms and 0.98 Å for methyl H atoms, respectively, and with Uiso(H) = 1.2Ueq(C) for aromatic and methylene H atoms and 1.5Ueq(C) for methyl H atoms.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level.
[Figure 2] Fig. 2. C—H···π interactions and hydrogen bonds (dotted lines) in (I). Cg denotes the ring centroid. [Symmetry code: (i) x, y - 1, z; (ii) -x + 1, -y + 1, -z + 2; (iii) -x + 1, -y, -z + 2; (iv) x, y + 1, z.]
2-(6,7-Dimethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetic acid top
Crystal data top
C13H14O3SF000 = 528
Mr = 250.30Dx = 1.386 Mg m−3
Monoclinic, P21/cMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P_2ybcCell parameters from 4188 reflections
a = 18.050 (2) Åθ = 3.0–28.3º
b = 4.9422 (5) ŵ = 0.26 mm−1
c = 13.885 (1) ÅT = 173 (2) K
β = 104.451 (2)ºBlock, colorless
V = 1199.4 (2) Å30.40 × 0.20 × 0.10 mm
Z = 4
Data collection top
Bruker SMART CCD
diffractometer		2595 independent reflections
Radiation source: fine-focus sealed tube2269 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.035
Detector resolution: 10.0 pixels mm-1θmax = 27.0º
T = 173(2) Kθmin = 1.2º
φ and ω scansh = −19→23
Absorption correction: nonek = −5→6
6673 measured reflectionsl = −17→17
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difmap (O-H) and geom (C-H)
R[F2 > 2σ(F2)] = 0.038H atoms treated by a mixture of
independent and constrained refinement
wR(F2) = 0.119  w = 1/[σ2(Fo2) + (0.0641P)2 + 0.395P]
where P = (Fo2 + 2Fc2)/3
S = 1.17(Δ/σ)max < 0.001
2595 reflectionsΔρmax = 0.42 e Å−3
161 parametersΔρmin = −0.25 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
C13H14O3SV = 1199.4 (2) Å3
Mr = 250.30Z = 4
Monoclinic, P21/cMo Kα
a = 18.050 (2) ŵ = 0.26 mm−1
b = 4.9422 (5) ÅT = 173 (2) K
c = 13.885 (1) Å0.40 × 0.20 × 0.10 mm
β = 104.451 (2)º
Data collection top
Bruker SMART CCD
diffractometer		2595 independent reflections
Absorption correction: none2269 reflections with I > 2σ(I)
6673 measured reflectionsRint = 0.035
Refinement top
R[F2 > 2σ(F2)] = 0.038161 parameters
wR(F2) = 0.119H atoms treated by a mixture of
independent and constrained refinement
S = 1.17Δρmax = 0.42 e Å−3
2595 reflectionsΔρmin = −0.25 e Å−3
Special details top

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 (Å2) top
xyzUiso*/Ueq
S0.36076 (2)0.71244 (9)0.66542 (3)0.02429 (16)
O10.22123 (6)0.3898 (3)0.81259 (8)0.0204 (3)
O20.40090 (8)0.3577 (3)0.94500 (11)0.0324 (4)
H2O0.4453 (16)0.310 (6)0.970 (2)0.049 (8)*
O30.45128 (7)0.7710 (3)0.96729 (10)0.0284 (3)
C10.29079 (9)0.5385 (3)0.70833 (12)0.0189 (4)
C20.23677 (9)0.3392 (4)0.65574 (12)0.0189 (4)
C30.21948 (10)0.2279 (4)0.56064 (13)0.0235 (4)
H30.24630.28110.51290.028*
C40.16167 (10)0.0365 (4)0.53846 (13)0.0252 (4)
H40.1490−0.04180.47390.030*
C50.12090 (10)−0.0469 (4)0.60716 (13)0.0229 (4)
C60.13800 (9)0.0629 (4)0.70363 (13)0.0209 (4)
C70.19588 (9)0.2551 (3)0.72277 (12)0.0187 (4)
C80.27891 (9)0.5601 (4)0.80010 (12)0.0192 (4)
C90.05928 (11)−0.2584 (4)0.57689 (16)0.0311 (5)
H9A0.0729−0.41810.61950.047*
H9B0.0543−0.30970.50740.047*
H9C0.0105−0.18490.58410.047*
C100.09738 (11)−0.0203 (4)0.78102 (15)0.0316 (5)
H10A0.11970.07520.84340.047*
H10B0.1029−0.21590.79210.047*
H10C0.04300.02560.75810.047*
C110.31794 (10)0.7259 (4)0.88784 (13)0.0221 (4)
H11A0.28650.72550.93700.026*
H11B0.32180.91520.86630.026*
C120.39713 (10)0.6221 (4)0.93705 (12)0.0197 (4)
C130.43420 (11)0.4564 (4)0.68607 (16)0.0315 (4)
H13A0.45290.42300.75760.047*
H13B0.47660.51830.65920.047*
H13C0.41300.28870.65260.047*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S0.0226 (3)0.0218 (3)0.0288 (3)−0.00298 (17)0.00704 (18)0.00404 (18)
O10.0180 (6)0.0248 (7)0.0181 (6)−0.0020 (5)0.0039 (4)−0.0033 (5)
O20.0245 (7)0.0204 (7)0.0432 (8)0.0008 (5)−0.0081 (6)0.0012 (6)
O30.0204 (6)0.0229 (7)0.0377 (7)−0.0021 (5)−0.0005 (5)−0.0019 (6)
C10.0161 (8)0.0183 (8)0.0211 (8)0.0002 (6)0.0021 (6)0.0017 (7)
C20.0157 (8)0.0201 (9)0.0192 (8)0.0011 (6)0.0009 (6)0.0004 (7)
C30.0239 (9)0.0265 (10)0.0196 (8)−0.0009 (7)0.0041 (7)−0.0021 (7)
C40.0266 (9)0.0251 (10)0.0206 (8)−0.0013 (7)−0.0002 (7)−0.0060 (7)
C50.0179 (8)0.0190 (9)0.0277 (9)0.0006 (6)−0.0019 (7)−0.0017 (7)
C60.0165 (8)0.0190 (9)0.0258 (9)0.0008 (6)0.0027 (6)0.0019 (7)
C70.0171 (8)0.0195 (9)0.0178 (8)0.0019 (6)0.0009 (6)−0.0014 (7)
C80.0153 (8)0.0186 (9)0.0218 (8)0.0012 (6)0.0011 (6)−0.0010 (7)
C90.0256 (10)0.0243 (10)0.0384 (11)−0.0052 (7)−0.0012 (8)−0.0028 (8)
C100.0259 (10)0.0350 (11)0.0354 (10)−0.0061 (8)0.0106 (8)0.0015 (9)
C110.0206 (9)0.0203 (9)0.0221 (8)0.0014 (7)−0.0006 (7)−0.0047 (7)
C120.0218 (9)0.0209 (9)0.0156 (7)−0.0002 (7)0.0032 (6)−0.0027 (7)
C130.0258 (10)0.0310 (11)0.0402 (11)0.0012 (8)0.0127 (8)0.0018 (9)
Geometric parameters (Å, °) top
S—C11.7506 (17)C5—C91.507 (2)
S—C131.803 (2)C6—C71.388 (2)
O1—C81.383 (2)C6—C101.502 (2)
O1—C71.387 (2)C8—C111.491 (2)
O2—C121.312 (2)C9—H9A0.9800
O2—H2O0.83 (3)C9—H9B0.9800
O3—C121.212 (2)C9—H9C0.9800
C1—C81.348 (2)C10—H10A0.9800
C1—C21.449 (2)C10—H10B0.9800
C2—C71.388 (2)C10—H10C0.9800
C2—C31.392 (2)C11—C121.512 (2)
C3—C41.385 (3)C11—H11A0.9900
C3—H30.9500C11—H11B0.9900
C4—C51.404 (3)C13—H13A0.9800
C4—H40.9500C13—H13B0.9800
C5—C61.407 (2)C13—H13C0.9800
C1—S—C1399.52 (9)C5—C9—H9A109.5
C8—O1—C7105.6 (1)C5—C9—H9B109.5
C12—O2—H2O110 (2)H9A—C9—H9B109.5
C8—C1—C2106.5 (2)C5—C9—H9C109.5
C8—C1—S125.5 (1)H9A—C9—H9C109.5
C2—C1—S127.9 (1)H9B—C9—H9C109.5
C7—C2—C3119.2 (2)C6—C10—H10A109.5
C7—C2—C1105.6 (1)C6—C10—H10B109.5
C3—C2—C1135.3 (2)H10A—C10—H10B109.5
C4—C3—C2117.3 (2)C6—C10—H10C109.5
C4—C3—H3121.3H10A—C10—H10C109.5
C2—C3—H3121.3H10B—C10—H10C109.5
C3—C4—C5122.9 (2)C8—C11—C12112.5 (1)
C3—C4—H4118.6C8—C11—H11A109.1
C5—C4—H4118.6C12—C11—H11A109.1
C4—C5—C6120.4 (2)C8—C11—H11B109.1
C4—C5—C9119.3 (2)C12—C11—H11B109.1
C6—C5—C9120.3 (2)H11A—C11—H11B107.8
C7—C6—C5115.0 (2)O3—C12—O2123.7 (2)
C7—C6—C10121.9 (2)O3—C12—C11122.7 (2)
C5—C6—C10123.1 (2)O2—C12—C11113.5 (2)
O1—C7—C6124.4 (2)S—C13—H13A109.5
O1—C7—C2110.4 (1)S—C13—H13B109.5
C6—C7—C2125.3 (2)H13A—C13—H13B109.5
C1—C8—O1111.9 (2)S—C13—H13C109.5
C1—C8—C11131.4 (2)H13A—C13—H13C109.5
O1—C8—C11116.7 (2)H13B—C13—H13C109.5
C13—S—C1—C896.66 (17)C10—C6—C7—O1−0.7 (3)
C13—S—C1—C2−80.90 (17)C5—C6—C7—C2−0.8 (3)
C8—C1—C2—C7−0.11 (19)C10—C6—C7—C2178.93 (17)
S—C1—C2—C7177.82 (13)C3—C2—C7—O1−179.69 (15)
C8—C1—C2—C3179.6 (2)C1—C2—C7—O10.06 (18)
S—C1—C2—C3−2.5 (3)C3—C2—C7—C60.6 (3)
C7—C2—C3—C4−0.1 (3)C1—C2—C7—C6−179.65 (16)
C1—C2—C3—C4−179.80 (19)C2—C1—C8—O10.13 (19)
C2—C3—C4—C50.0 (3)S—C1—C8—O1−177.87 (12)
C3—C4—C5—C6−0.3 (3)C2—C1—C8—C11178.24 (17)
C3—C4—C5—C9−179.47 (17)S—C1—C8—C110.2 (3)
C4—C5—C6—C70.7 (2)C7—O1—C8—C1−0.09 (18)
C9—C5—C6—C7179.84 (16)C7—O1—C8—C11−178.51 (14)
C4—C5—C6—C10−179.11 (17)C1—C8—C11—C12−72.5 (2)
C9—C5—C6—C100.1 (3)O1—C8—C11—C12105.56 (17)
C8—O1—C7—C6179.73 (16)C8—C11—C12—O3138.89 (18)
C8—O1—C7—C20.01 (18)C8—C11—C12—O2−42.1 (2)
C5—C6—C7—O1179.48 (15)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C9—H9A···Cgi0.982.863.617 (2)135
O2—H2O···O3ii0.83 (3)1.89 (3)2.717 (2)175 (3)
Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+1, −z+2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C9—H9A···Cgi0.982.863.617 (2)135
O2—H2O···O3ii0.83 (3)1.89 (3)2.717 (2)175 (3)
Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+1, −z+2.
references
References top

Brandenburg, K. (1998). DIAMOND. Crystal Impact GbR, Bonn, Germany.

Bruker (2001). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.

Choi, H. D., Seo, P. J., Son, B. W. & Lee, U. (2007). Acta Cryst. E63, o3468.

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.

Seo, P. J., Choi, H. D., Son, B. W. & Lee, U. (2007). Acta Cryst. E63, o2048–o2049.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.