Ethyl 2-(5-methyl-3-methyl­sulfinyl-1-benzofuran-2-yl)acetate

The title compound, C₁₄H₁₆O₄S, was prepared by the oxidation of ethyl 2-(5-methyl-3-methyl­sulfanyl-1-benzofuran-2-yl)acetate using 3-chloro­perbenzoic acid. The O atom and the methyl group of the methyl­sulfinyl substituent lie on opposite sides of the plane of the benzofuran fragment. The crystal structure is stabilized by inter­molecular aromatic π–π inter­actions with a centroid–centroid distance of 3.641 (3) Å between benzene rings of neighboring mol­ecules, and by two C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.048
• wR factor = 0.110
• Data-to-parameter ratio = 14.0

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low .......       0.94

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

Alert level C
REFLT03_ALERT_3_C  Reflection count < 95% complete
           From the CIF: _diffrn_reflns_theta_max           25.50
           From the CIF: _diffrn_reflns_theta_full          25.50
           From the CIF: _reflns_number_total               2416
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns         2574
           Completeness (_total/calc)             93.86%
PLAT022_ALERT_3_C Ratio Unique / Expected Reflections too Low ....       0.94

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

PLAT154_ALERT_1_C The su's on the Cell Angles are Equal  (x 10000)        200 Deg.
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.76 Ratio

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

   1 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
   3 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

As part of our ongoing work on the synthesis and structure of 2-benzofuranacetic acid derivatives, the crystal structures of ethyl [5-(4-hydroxyphenyl)-3-methylsulfanyl-1-benzofuran-2-yl]acetate (Choi et al., 2006) and 2-(5-ethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetic acid (Seo et al., 2007) have been described previously. Herein we report the molecular and crystal structure of the title compound (Fig. 1).

The benzofuran unit is essentially planar, with a mean deviation of 0.007 Å from the least-squares plane defined by the nine constituent atoms. The molecular packing (Fig. 2) is stabilized by π···π stacking interactions between adjacent benzene units. The Cg···Cgⁱⁱⁱ distance is 3.641 (3) Å (Cg is the centroid of the C2—C7 benzene ring; symmetry code as in Fig. 2). The molecular packing is further stabilized by two kinds of C—H···O hydrogen bonds between the oxygen of the S═O group and hydrogen atoms on the benzene ring and of the benzylic methylene group respectively (Table 1 and Fig. 2).

Related literature

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

S2. Experimental

3-Chloroperbenzoic acid (77%, 336 mg, 1.50 mmol) was added in small portions to a stirred solution of ethyl 2-(5-methyl-3-methylsulfanyl-1-benzofuran-2-yl)acetate (370 mg, 1.40 mmol) in dichloromethane (30 ml) at 273 K. After being stirred at room temperature for 2 h, the mixture was washed with saturated sodium bicarbonate solution and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated in vacuum. The residue was purified by column chromatography (ethyl acetate) to afford the title compound as a colorless solid [yield 88%, m.p. 426–427 K; R_f = 0.56 (ethyl acetate)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a dilute solution of the title compound in tetrahydrofuran at room temperature.

S3. Refinement

All 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, respectively, and with U_iso(H) = 1.2Ueq(C) for aromatic and methylene H atoms and 1.5Ueq(C) for methyl H atoms. The highest peak in the difference map is 1.06 Å from S and the largest hole is 0.52 Å from S.

The crystals were small and weakly diffracting and some of the weak high angle intensities could not be detected. This resulted in a lower than normal data completeness.

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); 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 (Sheldrick, 1997).

Figures

	Fig. 1. The molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. π···π and C—H···O hydrogen bond interactions (dashed lines) in title compound. Cg denotes the ring centroid. [Symmetry codes: (i) 2 - x, 1 - y, 2 - z; (ii) 1 - x, 1 - y, 2 - z; (iii) 2 - x, 1 - y, 1 - z.]

Ethyl 2-(5-methyl-3-methylsulfinyl-1-benzofuran-2-yl)acetate

Crystal data

C14H16O4S	Z = 2
Mr = 280.33	F(000) = 296
Triclinic, P1	Dx = 1.350 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.1499 (8) Å	Cell parameters from 2164 reflections
b = 9.4958 (9) Å	θ = 2.8–28.2°
c = 10.283 (1) Å	µ = 0.24 mm^−1
α = 73.216 (2)°	T = 173 K
β = 79.023 (2)°	Block, colorless
γ = 65.188 (2)°	0.40 × 0.20 × 0.10 mm
V = 689.37 (12) Å^3

Data collection

Bruker SMART CCD diffractometer	2020 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.044
Graphite monochromator	θmax = 25.5°, θmin = 2.1°
Detector resolution: 10.00 pixels mm^-1	h = −9→9
φ and ω scans	k = −11→9
3639 measured reflections	l = −12→12
2416 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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.110	H-atom parameters constrained
S = 1.13	w = 1/[σ^2(Fo^2) + (0.0258P)^2 + 0.6897P] where P = (Fo^2 + 2Fc^2)/3
2416 reflections	(Δ/σ)max < 0.001
173 parameters	Δρmax = 0.37 e Å^−3
0 restraints	Δρmin = −0.25 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	0.77608 (9)	0.37116 (9)	0.95947 (6)	0.0313 (2)
O1	0.6542 (2)	0.54093 (19)	0.57810 (16)	0.0239 (4)
O2	0.7583 (3)	0.4964 (3)	1.0281 (2)	0.0471 (6)
O3	0.5072 (2)	0.1180 (2)	0.7741 (2)	0.0371 (5)
O4	0.7751 (3)	0.1114 (2)	0.8028 (2)	0.0426 (5)
C1	0.7611 (3)	0.4609 (3)	0.7840 (2)	0.0227 (5)
C2	0.8480 (3)	0.5637 (3)	0.6972 (2)	0.0223 (5)
C3	0.9769 (3)	0.6190 (3)	0.7105 (3)	0.0255 (6)
H3	1.0284	0.5886	0.7948	0.031*
C4	1.0282 (3)	0.7195 (3)	0.5981 (3)	0.0281 (6)
C5	0.9505 (3)	0.7637 (3)	0.4743 (3)	0.0293 (6)
H5	0.9867	0.8329	0.3987	0.035*
C6	0.8229 (3)	0.7102 (3)	0.4582 (3)	0.0280 (6)
H6	0.7711	0.7404	0.3741	0.034*
C7	0.7755 (3)	0.6100 (3)	0.5722 (2)	0.0233 (5)
C8	0.6482 (3)	0.4513 (3)	0.7094 (2)	0.0225 (5)
C9	0.5246 (3)	0.3651 (3)	0.7405 (3)	0.0258 (6)
H9A	0.4543	0.3977	0.6608	0.031*
H9B	0.4375	0.3979	0.8181	0.031*
C10	0.6202 (3)	0.1852 (3)	0.7753 (2)	0.0264 (6)
C11	0.5784 (4)	−0.0565 (3)	0.8073 (4)	0.0482 (8)
H11A	0.6075	−0.0994	0.9037	0.058*
H11B	0.6907	−0.0987	0.7490	0.058*
C12	0.4391 (5)	−0.1053 (4)	0.7841 (5)	0.0621 (11)
H12A	0.4842	−0.2221	0.8058	0.093*
H12B	0.4116	−0.0628	0.6883	0.093*
H12C	0.3288	−0.0635	0.8426	0.093*
C13	1.1675 (4)	0.7805 (4)	0.6083 (3)	0.0399 (7)
H13A	1.1795	0.7681	0.7045	0.060*
H13B	1.1290	0.8936	0.5614	0.060*
H13C	1.2846	0.7195	0.5658	0.060*
C14	1.0112 (4)	0.2413 (4)	0.9549 (3)	0.0397 (7)
H14A	1.0434	0.1802	1.0475	0.060*
H14B	1.0852	0.3049	0.9173	0.060*
H14C	1.0335	0.1677	0.8975	0.060*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S	0.0308 (4)	0.0403 (4)	0.0203 (3)	−0.0133 (3)	−0.0046 (3)	−0.0026 (3)
O1	0.0259 (9)	0.0238 (9)	0.0226 (8)	−0.0109 (8)	−0.0074 (7)	−0.0011 (7)
O2	0.0454 (12)	0.0636 (15)	0.0336 (11)	−0.0129 (11)	−0.0062 (9)	−0.0239 (10)
O3	0.0294 (10)	0.0217 (10)	0.0614 (13)	−0.0105 (8)	−0.0105 (9)	−0.0062 (9)
O4	0.0308 (11)	0.0278 (11)	0.0640 (14)	−0.0097 (9)	−0.0166 (10)	0.0028 (10)
C1	0.0242 (12)	0.0212 (13)	0.0210 (12)	−0.0063 (10)	−0.0033 (10)	−0.0053 (10)
C2	0.0226 (12)	0.0193 (13)	0.0236 (12)	−0.0041 (10)	−0.0034 (10)	−0.0079 (10)
C3	0.0246 (13)	0.0242 (14)	0.0302 (13)	−0.0079 (11)	−0.0054 (11)	−0.0103 (11)
C4	0.0235 (13)	0.0203 (14)	0.0421 (15)	−0.0054 (11)	−0.0039 (11)	−0.0138 (11)
C5	0.0291 (14)	0.0212 (14)	0.0347 (14)	−0.0097 (11)	−0.0001 (11)	−0.0038 (11)
C6	0.0292 (13)	0.0253 (14)	0.0258 (13)	−0.0074 (11)	−0.0058 (11)	−0.0033 (11)
C7	0.0216 (12)	0.0191 (13)	0.0286 (13)	−0.0059 (10)	−0.0048 (10)	−0.0061 (10)
C8	0.0233 (12)	0.0188 (13)	0.0219 (12)	−0.0053 (10)	−0.0019 (10)	−0.0041 (9)
C9	0.0236 (13)	0.0267 (14)	0.0270 (13)	−0.0103 (11)	−0.0028 (10)	−0.0047 (10)
C10	0.0272 (14)	0.0271 (14)	0.0249 (12)	−0.0121 (12)	−0.0036 (10)	−0.0028 (10)
C11	0.0380 (17)	0.0211 (16)	0.081 (2)	−0.0065 (13)	−0.0117 (16)	−0.0084 (15)
C12	0.046 (2)	0.0267 (18)	0.114 (3)	−0.0151 (15)	−0.010 (2)	−0.0145 (19)
C13	0.0368 (16)	0.0348 (17)	0.0541 (18)	−0.0197 (14)	−0.0066 (14)	−0.0082 (14)
C14	0.0374 (16)	0.0379 (17)	0.0356 (15)	−0.0065 (13)	−0.0157 (13)	−0.0009 (13)

Geometric parameters (Å, º)

S—O2	1.495 (2)	C6—C7	1.386 (4)
S—C1	1.763 (2)	C6—H6	0.9500
S—C14	1.792 (3)	C8—C9	1.485 (3)
O1—C8	1.377 (3)	C9—C10	1.513 (4)
O1—C7	1.382 (3)	C9—H9A	0.9900
O3—C10	1.326 (3)	C9—H9B	0.9900
O3—C11	1.463 (3)	C11—C12	1.473 (4)
O4—C10	1.202 (3)	C11—H11A	0.9900
C1—C8	1.350 (3)	C11—H11B	0.9900
C1—C2	1.444 (3)	C12—H12A	0.9800
C2—C7	1.393 (3)	C12—H12B	0.9800
C2—C3	1.399 (3)	C12—H12C	0.9800
C3—C4	1.391 (4)	C13—H13A	0.9800
C3—H3	0.9500	C13—H13B	0.9800
C4—C5	1.405 (4)	C13—H13C	0.9800
C4—C13	1.506 (4)	C14—H14A	0.9800
C5—C6	1.388 (4)	C14—H14B	0.9800
C5—H5	0.9500	C14—H14C	0.9800
O2—S—C1	106.9 (1)	C10—C9—H9A	108.7
O2—S—C14	106.4 (1)	C8—C9—H9B	108.7
C1—S—C14	98.7 (1)	C10—C9—H9B	108.7
C8—O1—C7	106.2 (2)	H9A—C9—H9B	107.6
C10—O3—C11	117.2 (2)	O4—C10—O3	123.9 (2)
C8—C1—C2	107.9 (2)	O4—C10—C9	125.8 (2)
C8—C1—S	122.7 (2)	O3—C10—C9	110.3 (2)
C2—C1—S	129.2 (2)	O3—C11—C12	108.2 (2)
C7—C2—C3	119.2 (2)	O3—C11—H11A	110.1
C7—C2—C1	104.3 (2)	C12—C11—H11A	110.1
C3—C2—C1	136.4 (2)	O3—C11—H11B	110.1
C4—C3—C2	118.8 (2)	C12—C11—H11B	110.1
C4—C3—H3	120.6	H11A—C11—H11B	108.4
C2—C3—H3	120.6	C11—C12—H12A	109.5
C3—C4—C5	119.9 (2)	C11—C12—H12B	109.5
C3—C4—C13	120.3 (2)	H12A—C12—H12B	109.5
C5—C4—C13	119.8 (2)	C11—C12—H12C	109.5
C6—C5—C4	122.5 (2)	H12A—C12—H12C	109.5
C6—C5—H5	118.8	H12B—C12—H12C	109.5
C4—C5—H5	118.8	C4—C13—H13A	109.5
C7—C6—C5	116.0 (2)	C4—C13—H13B	109.5
C7—C6—H6	122.0	H13A—C13—H13B	109.5
C5—C6—H6	122.0	C4—C13—H13C	109.5
O1—C7—C6	125.6 (2)	H13A—C13—H13C	109.5
O1—C7—C2	110.8 (2)	H13B—C13—H13C	109.5
C6—C7—C2	123.6 (2)	S—C14—H14A	109.5
C1—C8—O1	110.8 (2)	S—C14—H14B	109.5
C1—C8—C9	133.3 (2)	H14A—C14—H14B	109.5
O1—C8—C9	115.9 (2)	S—C14—H14C	109.5
C8—C9—C10	114.1 (2)	H14A—C14—H14C	109.5
C8—C9—H9A	108.7	H14B—C14—H14C	109.5
O2—S—C1—C8	−129.7 (2)	C5—C6—C7—C2	0.2 (4)
C14—S—C1—C8	120.2 (2)	C3—C2—C7—O1	178.7 (2)
O2—S—C1—C2	45.0 (3)	C1—C2—C7—O1	−0.7 (3)
C14—S—C1—C2	−65.1 (3)	C3—C2—C7—C6	−0.4 (4)
C8—C1—C2—C7	0.4 (3)	C1—C2—C7—C6	−179.8 (2)
S—C1—C2—C7	−174.91 (19)	C2—C1—C8—O1	0.1 (3)
C8—C1—C2—C3	−178.9 (3)	S—C1—C8—O1	175.77 (16)
S—C1—C2—C3	5.8 (4)	C2—C1—C8—C9	179.6 (3)
C7—C2—C3—C4	0.2 (4)	S—C1—C8—C9	−4.7 (4)
C1—C2—C3—C4	179.4 (3)	C7—O1—C8—C1	−0.6 (3)
C2—C3—C4—C5	0.1 (4)	C7—O1—C8—C9	179.8 (2)
C2—C3—C4—C13	−179.6 (2)	C1—C8—C9—C10	−64.4 (4)
C3—C4—C5—C6	−0.3 (4)	O1—C8—C9—C10	115.1 (2)
C13—C4—C5—C6	179.4 (2)	C11—O3—C10—O4	−0.6 (4)
C4—C5—C6—C7	0.1 (4)	C11—O3—C10—C9	−179.3 (2)
C8—O1—C7—C6	179.9 (2)	C8—C9—C10—O4	14.1 (4)
C8—O1—C7—C2	0.8 (3)	C8—C9—C10—O3	−167.2 (2)
C5—C6—C7—O1	−178.7 (2)	C10—O3—C11—C12	−173.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···O2^i	0.95	2.48	3.407 (3)	164
C9—H9B···O2^ii	0.99	2.16	3.143 (3)	172

Symmetry codes: (i) −x+2, −y+1, −z+2; (ii) −x+1, −y+1, −z+2.