2-(3-Methyl­sulfanyl-5-phenyl-1-benzofuran-2-yl)acetic acid

The title compound, C₁₇H₁₄O₃S, was prepared by alkaline hydrolysis of ethyl 2-(3-methyl­sulfanyl-5-phenyl-1-benzofuran-2-yl)acetate. The phenyl ring is rotated out of the benzofuran plane with a dihedral angle of 44.1 (1)°. The methyl group of the methyl­sulfanyl substituent is almost perpendicular to the plane of the benzofuran fragment [100.4 (2)°] and is slightly tilted towards it. The crystal structure is stabilized by aromatic π–π inter­actions, with a centroid-to-centroid distance of 3.566 (5) Å between furan rings of neighboring mol­ecules, and by inversion-related inter­molecular O—H...O hydrogen bonds between the carboxyl groups.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.060
• wR factor = 0.152
• Data-to-parameter ratio = 12.3

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low .......       0.92

Author Response: Some high-angle reflections were not correctly measured.

Alert level B
SYMMS01_ALERT_1_B  The cell setting should be one of the following
            *  triclinic
            *  monoclinic
            *  orthorhombic
            *  tetragonal
            *  rhombohedral
            *  trigonal
            *  hexagonal
            *  cubic
            Cell setting given = monoclinic'
PLAT222_ALERT_3_B Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       4.58 Ratio

Author Response: High U value for H of OH group.

Alert level C
REFLT03_ALERT_3_C  Reflection count < 95% complete
           From the CIF: _diffrn_reflns_theta_max           25.00
           From the CIF: _diffrn_reflns_theta_full          25.00
           From the CIF: _reflns_number_total               2390
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns         2586
           Completeness (_total/calc)             92.42%
PLAT022_ALERT_3_C Ratio Unique / Expected Reflections too Low ....       0.92
PLAT153_ALERT_1_C The su's on the Cell Axes   are Equal (x 100000)        200 Ang.
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.89 Ratio
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          5

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   6 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

This work is related to our previous communications on the synthesis and structure of 2-(3-methylsulfanyl-1-benzofuran-2-yl)acetic acid analogues (Choi et al., 2006; Seo et al., 2007). Here we report the crystal structure of the title compound (Fig. 1).

The benzofuran unit is essentially planar, with a mean deviation of 0.012 Å from the least-squares plane defined by the nine constituent atoms. In the title compound, the dihedral angle formed by the plane of the benzofuran unit and the plane of the phenyl ring is 44.1 (1)°. The molecular packing (Fig. 2) is stabilized by π···π stacking interactions between furan rings of adjacent benzofuran systems, with a Cg···Cgⁱ distance of 3.566 (5) Å (Cg is the centroid of the O1/C8/C1/C2/C7 ring; symmetry code as in Fig. 2). Classical inversion-related O3—H1···O2ⁱ hydrogen bonds link the carboxyl groups of adjacent molecules (Table 1 and Fig. 2).

Related literature

For the crystal structures of isomers of the title compound, see: Choi et al. (2006) and Seo et al. (2007).

S2. Experimental

Ethyl 2-(3-methylsulfanyl-5-phenyl-1-benzofuran-2-yl)acetate (652 mg, 2.0 mmol) was added to a solution of potassium hydroxide (561 mg, 10.0 mmol) in water (10 ml) and methanol (10 ml), and the mixture was heated at 333 K for 4hrs, then cooled. Water was added, and the solution was washed 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 87%, m.p. 460–461 K; R_f = 0.64 (ethyl acetate)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a dilute solution of the title compound in acetone at room temperature.

S3. Refinement

Atom H1 of the hydroxy group was found in a difference Fourier map and refined with O—H restrained to 0.9 (1) Å. The other H atoms were positioned geometrically and refined using a riding model, with C—H = 0.95 Å for aromatic H atoms, 0.98 Å for methyl H atoms and 0.99 Å for methylene H atoms, and with U_iso(H) = 1.2U_eq(C) for aromatic and methylene H atoms and U_iso(H) = 1.5U_eq(C) for methyl H atoms.

Computing details

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

Figures

	Fig. 1. The molecular structure of the title compound, showing displacement ellipsoides drawn at the 50% probability level.
	Fig. 2. π—π interactions (dotted lines) in the title compound. Cg denotes the ring centroid. [Symmetry code: (i) -x, 1 - y, 2 - z; (ii) -x, 1 - y, 1 - z.]

2-(3-Methylsulfanyl-5-phenyl-1-benzofuran-2-yl)acetic acid

Crystal data

C17H14O3S	F(000) = 624
Mr = 298.34	Dx = 1.352 Mg m^−3
Monoclinic, P21/c	Melting point = 460–461 K
Hall symbol: -p_2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 10.857 (2) Å	Cell parameters from 1299 reflections
b = 11.274 (2) Å	θ = 2.5–27.1°
c = 11.978 (2) Å	µ = 0.23 mm^−1
β = 90.777 (4)°	T = 173 K
V = 1466.0 (4) Å^3	Block, colourless
Z = 4	0.40 × 0.10 × 0.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1573 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.076
Graphite monochromator	θmax = 25.0°, θmin = 2.5°
Detector resolution: 10.00 pixels mm^-1	h = −12→12
φ and ω scans	k = −11→13
5235 measured reflections	l = −14→14
2390 independent reflections

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)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.152	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0737P)^2 + 0.4676P] where P = (Fo^2 + 2Fc^2)/3
2390 reflections	(Δ/σ)max < 0.001
195 parameters	Δρmax = 0.41 e Å^−3
1 restraint	Δρmin = −0.30 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
S	0.14850 (10)	0.23359 (9)	0.57947 (9)	0.0309 (3)
O1	0.0811 (2)	0.5739 (2)	0.6300 (2)	0.0266 (7)
O2	−0.1048 (2)	0.4462 (2)	0.9100 (2)	0.0265 (7)
O3	0.0877 (2)	0.5047 (3)	0.8757 (2)	0.0297 (7)
H1	0.099 (6)	0.526 (6)	0.954 (5)	0.11 (2)*
C1	0.1424 (3)	0.3886 (3)	0.5843 (3)	0.0198 (9)
C2	0.2125 (3)	0.4721 (3)	0.5198 (3)	0.0189 (9)
C3	0.3023 (3)	0.4618 (3)	0.4376 (3)	0.0203 (9)
H3	0.3308	0.3859	0.4150	0.024*
C4	0.3495 (3)	0.5651 (3)	0.3894 (3)	0.0200 (9)
C5	0.3068 (3)	0.6753 (4)	0.4257 (3)	0.0232 (9)
H5	0.3402	0.7450	0.3933	0.028*
C6	0.2181 (3)	0.6875 (4)	0.5067 (3)	0.0250 (9)
H6	0.1906	0.7630	0.5313	0.030*
C7	0.1722 (3)	0.5836 (3)	0.5494 (3)	0.0205 (9)
C8	0.0665 (3)	0.4546 (4)	0.6483 (3)	0.0234 (9)
C9	−0.0320 (3)	0.4211 (4)	0.7269 (3)	0.0307 (11)
H9A	−0.0398	0.3336	0.7260	0.037*
H9B	−0.1107	0.4540	0.6979	0.037*
C10	−0.0165 (3)	0.4601 (3)	0.8469 (3)	0.0220 (9)
C11	0.4407 (3)	0.5580 (3)	0.2981 (3)	0.0198 (9)
C12	0.4281 (3)	0.6317 (4)	0.2039 (3)	0.0275 (10)
H12	0.3616	0.6863	0.1987	0.033*
C13	0.5120 (4)	0.6246 (4)	0.1194 (3)	0.0332 (11)
H13	0.5007	0.6726	0.0549	0.040*
C14	0.6120 (4)	0.5496 (4)	0.1259 (3)	0.0325 (11)
H14	0.6703	0.5469	0.0674	0.039*
C15	0.6258 (3)	0.4784 (4)	0.2191 (3)	0.0254 (10)
H15	0.6948	0.4268	0.2249	0.030*
C16	0.5411 (3)	0.4812 (3)	0.3036 (3)	0.0209 (9)
H16	0.5513	0.4303	0.3663	0.025*
C17	0.2897 (4)	0.2070 (4)	0.6565 (4)	0.0542 (15)
H17A	0.3571	0.2508	0.6218	0.081*
H17B	0.3084	0.1220	0.6559	0.081*
H17C	0.2803	0.2338	0.7338	0.081*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S	0.0362 (6)	0.0260 (6)	0.0304 (7)	−0.0089 (5)	−0.0004 (5)	−0.0024 (5)
O1	0.0237 (14)	0.0361 (18)	0.0201 (15)	0.0051 (12)	0.0003 (12)	−0.0009 (13)
O2	0.0220 (15)	0.0358 (17)	0.0219 (16)	−0.0052 (12)	0.0058 (12)	−0.0015 (13)
O3	0.0170 (14)	0.0507 (19)	0.0211 (17)	−0.0056 (13)	−0.0029 (12)	−0.0028 (14)
C1	0.0185 (19)	0.031 (2)	0.010 (2)	−0.0033 (17)	0.0002 (16)	0.0005 (18)
C2	0.0172 (19)	0.025 (2)	0.014 (2)	−0.0018 (16)	−0.0062 (16)	−0.0005 (17)
C3	0.022 (2)	0.021 (2)	0.018 (2)	0.0051 (16)	−0.0073 (17)	−0.0021 (17)
C4	0.0222 (19)	0.021 (2)	0.017 (2)	0.0012 (16)	−0.0099 (17)	−0.0011 (16)
C5	0.029 (2)	0.021 (2)	0.019 (2)	−0.0045 (17)	−0.0029 (18)	0.0068 (18)
C6	0.029 (2)	0.024 (2)	0.022 (2)	0.0079 (18)	−0.0023 (18)	−0.0013 (19)
C7	0.0145 (19)	0.030 (2)	0.017 (2)	0.0033 (16)	−0.0011 (16)	0.0004 (18)
C8	0.021 (2)	0.028 (2)	0.020 (2)	−0.0034 (17)	−0.0059 (18)	−0.0004 (18)
C9	0.024 (2)	0.043 (3)	0.025 (2)	−0.0077 (18)	−0.0028 (18)	−0.005 (2)
C10	0.020 (2)	0.023 (2)	0.023 (2)	0.0051 (16)	−0.0024 (18)	0.0014 (17)
C11	0.023 (2)	0.024 (2)	0.012 (2)	−0.0050 (16)	−0.0048 (17)	0.0003 (17)
C12	0.024 (2)	0.034 (2)	0.025 (2)	0.0004 (18)	−0.0076 (19)	0.0031 (19)
C13	0.032 (2)	0.048 (3)	0.019 (2)	−0.005 (2)	−0.0030 (19)	0.008 (2)
C14	0.026 (2)	0.050 (3)	0.022 (2)	−0.004 (2)	0.0050 (19)	−0.002 (2)
C15	0.025 (2)	0.030 (2)	0.021 (2)	0.0002 (17)	−0.0028 (18)	−0.0068 (18)
C16	0.020 (2)	0.030 (2)	0.012 (2)	−0.0023 (17)	−0.0011 (16)	0.0006 (17)
C17	0.069 (3)	0.035 (3)	0.058 (3)	0.012 (2)	−0.030 (3)	0.006 (2)

Geometric parameters (Å, º)

S—C1	1.749 (4)	C8—C9	1.483 (5)
S—C17	1.804 (4)	C9—C10	1.511 (5)
O1—C8	1.372 (5)	C9—H9A	0.990
O1—C7	1.397 (4)	C9—H9B	0.990
O2—C10	1.238 (4)	C11—C16	1.393 (5)
O3—C10	1.281 (4)	C11—C12	1.407 (5)
O3—H1	0.97 (6)	C12—C13	1.372 (5)
C1—C8	1.356 (5)	C12—H12	0.950
C1—C2	1.441 (5)	C13—C14	1.378 (6)
C2—C7	1.379 (5)	C13—H13	0.950
C2—C3	1.399 (5)	C14—C15	1.381 (6)
C3—C4	1.401 (5)	C14—H14	0.950
C3—H3	0.950	C15—C16	1.378 (5)
C4—C5	1.397 (5)	C15—H15	0.950
C4—C11	1.487 (5)	C16—H16	0.950
C5—C6	1.384 (5)	C17—H17A	0.980
C5—H5	0.950	C17—H17B	0.980
C6—C7	1.374 (5)	C17—H17C	0.980
C6—H6	0.950
C1—S—C17	100.4 (2)	C8—C9—H9B	108.0
C8—O1—C7	105.8 (3)	C10—C9—H9B	108.0
C10—O3—H1	117 (4)	H9A—C9—H9B	107.2
C8—C1—C2	105.9 (4)	O2—C10—O3	125.0 (3)
C8—C1—S	126.2 (3)	O2—C10—C9	117.8 (3)
C2—C1—S	127.9 (3)	O3—C10—C9	117.2 (4)
C7—C2—C3	118.9 (3)	C16—C11—C12	118.2 (4)
C7—C2—C1	106.6 (3)	C16—C11—C4	121.8 (3)
C3—C2—C1	134.5 (4)	C12—C11—C4	120.0 (3)
C4—C3—C2	118.9 (3)	C13—C12—C11	119.9 (4)
C4—C3—H3	120.5	C13—C12—H12	120.0
C2—C3—H3	120.5	C11—C12—H12	120.0
C5—C4—C3	119.1 (4)	C12—C13—C14	121.7 (4)
C5—C4—C11	120.2 (3)	C12—C13—H13	119.2
C3—C4—C11	120.6 (3)	C14—C13—H13	119.2
C6—C5—C4	122.9 (4)	C13—C14—C15	118.6 (4)
C6—C5—H5	118.5	C13—C14—H14	120.7
C4—C5—H5	118.5	C15—C14—H14	120.7
C7—C6—C5	115.8 (4)	C16—C15—C14	121.0 (4)
C7—C6—H6	122.1	C16—C15—H15	119.5
C5—C6—H6	122.1	C14—C15—H15	119.5
C6—C7—C2	124.3 (4)	C15—C16—C11	120.6 (4)
C6—C7—O1	126.0 (3)	C15—C16—H16	119.7
C2—C7—O1	109.6 (3)	C11—C16—H16	119.7
C1—C8—O1	112.0 (3)	S—C17—H17A	109.5
C1—C8—C9	132.0 (4)	S—C17—H17B	109.5
O1—C8—C9	115.9 (3)	H17A—C17—H17B	109.5
C8—C9—C10	117.3 (3)	S—C17—H17C	109.5
C8—C9—H9A	108.0	H17A—C17—H17C	109.5
C10—C9—H9A	108.0	H17B—C17—H17C	109.5
C17—S—C1—C8	−105.6 (4)	S—C1—C8—O1	−177.8 (2)
C17—S—C1—C2	76.6 (4)	C2—C1—C8—C9	176.0 (3)
C8—C1—C2—C7	−0.6 (4)	S—C1—C8—C9	−2.1 (6)
S—C1—C2—C7	177.6 (3)	C7—O1—C8—C1	−0.1 (4)
C8—C1—C2—C3	−178.1 (3)	C7—O1—C8—C9	−176.5 (3)
S—C1—C2—C3	0.0 (6)	C1—C8—C9—C10	120.0 (4)
C7—C2—C3—C4	0.9 (4)	O1—C8—C9—C10	−64.4 (4)
C1—C2—C3—C4	178.2 (3)	C8—C9—C10—O2	171.0 (3)
C2—C3—C4—C5	0.8 (5)	C8—C9—C10—O3	−9.4 (5)
C2—C3—C4—C11	−177.1 (3)	C5—C4—C11—C16	136.8 (4)
C3—C4—C5—C6	−0.9 (5)	C3—C4—C11—C16	−45.3 (5)
C11—C4—C5—C6	177.1 (3)	C5—C4—C11—C12	−42.0 (5)
C4—C5—C6—C7	−0.8 (5)	C3—C4—C11—C12	135.9 (4)
C5—C6—C7—C2	2.7 (5)	C16—C11—C12—C13	1.5 (5)
C5—C6—C7—O1	−178.8 (3)	C4—C11—C12—C13	−179.7 (3)
C3—C2—C7—C6	−2.8 (5)	C11—C12—C13—C14	−2.4 (6)
C1—C2—C7—C6	179.2 (3)	C12—C13—C14—C15	1.4 (6)
C3—C2—C7—O1	178.5 (3)	C13—C14—C15—C16	0.5 (6)
C1—C2—C7—O1	0.5 (4)	C14—C15—C16—C11	−1.4 (5)
C8—O1—C7—C6	−178.9 (3)	C12—C11—C16—C15	0.3 (5)
C8—O1—C7—C2	−0.3 (3)	C4—C11—C16—C15	−178.5 (3)
C2—C1—C8—O1	0.4 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1···O2^i	0.97 (6)	1.66 (6)	2.630 (4)	174 (6)

Symmetry code: (i) −x, −y+1, −z+2.