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Acta Cryst. (2008). E64, o2203    [ doi:10.1107/S1600536808034466 ]

Isopropyl 2-(4,6-dimethyl-3-methylsulfinyl-1-benzofuran-2-yl)acetate

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

Abstract top

Molecules of title compound, C16H20O4S, which was synthesized by the oxidation of isopropyl 2-(4,6-dimethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetate, interact through C-H...[pi] interactions between a methylene H atom and the aromatic carbon ring of the benzofuran ring system, and by C-H...O hydrogen bonds. Adjacent stacked molecules exhibit a carbonyl-carbonyl interaction [3.295 (2) Å]. The O atom of the methylsulfinyl group is disordered over two positions with site-occupancy factors of 0.9 and 0.1.

Comment top

This work is related to our previous communications on the synthesis and structure of alkyl 2-(3-methylsulfinyl-1-benzofuran-2-yl)acetate analogues, viz. ethyl 2-(5-methyl-3-methylsulfinyl-1-benzofuran-2-yl)acetate (Choi et al., 2007) and isopropyl 2-(5-methyl-3-methylsulfinyl-1-benzofuran-2-yl) acetate (Choi et al., 2008). Here we report the crystal structure of the title compound, isopropyl 2-(4,6-dimethyl-3-methylsulfinyl-1-benzofuran-2-yl) acetate (Fig. 1).

The benzofuran unit is essentially planar, with a mean deviation of 0.011 (2) Å from the least-squares plane defined by the nine constituent atoms. The O4 atom of the methylsulfinyl group is disordered over two positions with site-occupancy factors fixed at 0.9 (for atom O4A) and 0.1 (for atom O4B) in Fig. 1. The molecular packing (Fig. 2) is stabilized by C—H···π interactions between the hydrogen of 9-methylene group and a benzene ring of benzofuran unit, with a C9—H9B···Cgi separation of 2.99 Å (Fig. 2 & Table 1) (Cg is the centroid of C2–C7 benzene ring, symmetry code as in Fig. 2). The molecular packing is further stabilized by intermolecular C—H···O hydrogen bonds (Table 1). In addition, the crystal packing exhibits a type-II carbonyl–carbonyl interaction (Allen et al., 1998), with C10···O3 ii and O3···C10ii distance of 3.295 (2) Å (symmetry code as in Fig. 2).

Related literature top

For the crystal structures of similar alkyl 2-(3-methylsulfinyl-1-benzofuran- 2-yl)acetate derivatives, see: Choi et al. (2007, 2008). For a review of carbonyl–carbonyl interactions, see: Allen et al. (1998). Cg is the centroid of C2–C7 benzene ring.

Experimental top

77% 3-chloroperoxybenzoic acid (314 mg, 1.40 mmol) was added in small portions to a stirred solution of isopropyl 2-(4,6-dimethyl-3-methylsulfanyl-1-benzofuran-2-yl)acetate (380 mg, 1.30 mmol) in dichloromethane (40 ml) at 273 K. After being stirred for 3 h at room temperature, 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 (hexane-ethylcetate, 1:2 v/v) to afford the title compound as a colorless solid [yield 84%, m.p. 357–358 K; Rf = 0.77 (hexane-ethyl acetate, 1;2 v/v)]. Single crystals suitable for X-ray diffraction were prepared by evaporation of a solution of the title compound in acetone at room temperature. Spectroscopic analysis: 1H NMR (CDCl3, 400 MHz) δ 1.26 (d, J = 6.24 Hz, 6H), 2.42 (s, 3H), 2.62 (s, 3H), 2.99 (s, 3H), 4.34 (s, 2H), 5.00–5.08 (m, 1H), 6.93 (s, 1H), 7.13 (s, 1H); EI—MS 308 [M+].

Refinement top

All H atoms were geometrically positioned and refined using a riding model, with C—H = 0.98 (methine), 0.93 (aromatic), 0.97 (methylene), and 0.96 Å (methyl) H atoms, respectively, and with Uiso(H) = 1.2Ueq(C) (aromatic, methylene, methine), and 1.5Ueq(C) (methyl) H atoms. The O4 atom of the methylsulfinyl group is disordered over two positions with site-occupancy factors fixed at 0.90 (O4A) and 0.10 (O4B) in final refinement. The displacement ellipsoids of O4B was restrained using command ISOR (0.01) and both O4 atoms were restrained usig command DELU. The distances of S—O4 (A & B) were restrained using command SADI (0.001).

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 the title compound, showing displacement ellipsoids drawn at the 30% probability level.
[Figure 2] Fig. 2. C—H···π and C···O interactions (dotted lines) in the title compound. Cg denotes ring centroid. [Symmetry code: (i) x - 1, y, z; (ii) -x, -y, -z + 1; (iii) x + 1, y, z.]
Isopropyl 2-(4,6-dimethyl-3-methylsulfinyl-1-benzofuran-2-yl)acetate top
Crystal data top
C16H20O4SZ = 2
Mr = 308.38F(000) = 328
Triclinic, P1Dx = 1.296 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.308 (1) ÅCell parameters from 2459 reflections
b = 11.340 (2) Åθ = 2.4–28.0°
c = 11.506 (2) ŵ = 0.22 mm−1
α = 81.403 (3)°T = 298 K
β = 77.205 (3)°Block, colorless
γ = 83.167 (4)°0.40 × 0.30 × 0.10 mm
V = 790.4 (2) Å3
Data collection top
Bruker SMART CCD
diffractometer		2270 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.044
graphiteθmax = 25.0°, θmin = 2.4°
Detector resolution: 10.0 pixels mm-1h = −6→7
φ and ω scansk = −8→13
4195 measured reflectionsl = −13→13
2760 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: difference Fourier map
wR(F2) = 0.126H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0676P)2 + 0.1659P]
where P = (Fo2 + 2Fc2)/3
2760 reflections(Δ/σ)max < 0.001
202 parametersΔρmax = 0.40 e Å−3
7 restraintsΔρmin = −0.27 e Å−3
Crystal data top
C16H20O4Sγ = 83.167 (4)°
Mr = 308.38V = 790.4 (2) Å3
Triclinic, P1Z = 2
a = 6.308 (1) ÅMo Kα radiation
b = 11.340 (2) ŵ = 0.22 mm−1
c = 11.506 (2) ÅT = 298 K
α = 81.403 (3)°0.40 × 0.30 × 0.10 mm
β = 77.205 (3)°
Data collection top
Bruker SMART CCD
diffractometer		2270 reflections with I > 2σ(I)
4195 measured reflectionsRint = 0.044
2760 independent reflectionsθmax = 25.0°
Refinement top
R[F2 > 2σ(F2)] = 0.043H-atom parameters constrained
wR(F2) = 0.126Δρmax = 0.40 e Å−3
S = 1.06Δρmin = −0.27 e Å−3
2760 reflectionsAbsolute structure: ?
202 parametersFlack parameter: ?
7 restraintsRogers parameter: ?
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*/UeqOcc. (<1)
S0.14112 (9)0.43525 (5)0.31658 (6)0.0639 (2)
O10.2743 (2)0.14311 (12)0.15511 (12)0.0528 (4)
O2−0.2895 (2)0.15214 (13)0.49041 (11)0.0503 (4)
O30.0716 (2)0.13761 (14)0.48320 (14)0.0612 (4)
O4A−0.0855 (3)0.41447 (18)0.37312 (18)0.0742 (5)0.90
O4B0.082 (3)0.5555 (7)0.2602 (15)0.086 (5)0.10
C10.2493 (3)0.31729 (18)0.22999 (17)0.0471 (5)
C20.4558 (3)0.30687 (18)0.14521 (17)0.0480 (5)
C30.6322 (3)0.3783 (2)0.10060 (19)0.0573 (5)
C40.8036 (4)0.3295 (3)0.0188 (2)0.0697 (7)
H40.92310.3739−0.01180.084*
C50.8091 (4)0.2190 (3)−0.0207 (2)0.0705 (7)
C60.6334 (3)0.1514 (2)0.0214 (2)0.0634 (6)
H60.63070.0778−0.00440.076*
C70.4621 (3)0.19809 (19)0.10351 (17)0.0504 (5)
C80.1482 (3)0.21824 (18)0.23284 (17)0.0478 (5)
C9−0.0638 (3)0.1747 (2)0.30051 (18)0.0538 (5)
H9A−0.08260.10050.27320.065*
H9B−0.18140.23300.28250.065*
C10−0.0808 (3)0.15375 (17)0.43450 (18)0.0461 (4)
C11−0.3372 (3)0.13159 (19)0.62208 (17)0.0523 (5)
H11−0.21260.08500.64980.063*
C12−0.3741 (5)0.2506 (2)0.6681 (2)0.0836 (8)
H12A−0.49510.29670.64020.100*
H12B−0.24550.29270.63930.100*
H12C−0.40550.23890.75430.100*
C13−0.5315 (4)0.0596 (2)0.6574 (2)0.0671 (6)
H13A−0.4967−0.01440.62340.080*
H13B−0.65240.10410.62800.080*
H13C−0.56990.04300.74340.080*
C140.6363 (4)0.4994 (2)0.1375 (2)0.0748 (7)
H14A0.70170.49080.20650.112*
H14B0.48980.53600.15710.112*
H14C0.71990.54880.07250.112*
C151.0074 (4)0.1738 (4)−0.1096 (3)0.1018 (11)
H15A0.98170.0989−0.13110.153*
H15B1.13290.1626−0.07350.153*
H15C1.03270.2313−0.18040.153*
C160.3028 (4)0.3962 (2)0.4279 (2)0.0661 (6)
H16A0.26270.45150.48630.099*
H16B0.45430.39960.39050.099*
H16C0.27840.31660.46690.099*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S0.0584 (4)0.0639 (4)0.0712 (4)0.0072 (3)−0.0154 (3)−0.0215 (3)
O10.0453 (8)0.0637 (9)0.0494 (8)−0.0128 (6)0.0000 (6)−0.0156 (6)
O20.0364 (7)0.0699 (9)0.0424 (7)−0.0089 (6)−0.0025 (6)−0.0057 (6)
O30.0408 (8)0.0785 (10)0.0620 (9)−0.0078 (7)−0.0115 (7)0.0015 (7)
O4A0.0467 (10)0.0921 (14)0.0844 (13)0.0064 (9)−0.0059 (9)−0.0346 (10)
O4B0.088 (9)0.086 (8)0.088 (9)−0.014 (7)−0.012 (7)−0.027 (7)
C10.0400 (10)0.0573 (12)0.0441 (10)−0.0055 (8)−0.0075 (8)−0.0074 (8)
C20.0408 (10)0.0620 (12)0.0406 (10)−0.0089 (9)−0.0087 (8)−0.0012 (9)
C30.0474 (11)0.0727 (14)0.0510 (12)−0.0190 (10)−0.0111 (9)0.0069 (10)
C40.0452 (12)0.108 (2)0.0529 (13)−0.0264 (12)−0.0032 (10)0.0042 (13)
C50.0440 (12)0.116 (2)0.0469 (12)−0.0070 (12)0.0000 (10)−0.0109 (13)
C60.0504 (12)0.0878 (17)0.0509 (12)−0.0058 (11)−0.0005 (10)−0.0202 (11)
C70.0400 (10)0.0681 (13)0.0420 (10)−0.0106 (9)−0.0043 (8)−0.0051 (9)
C80.0392 (10)0.0619 (12)0.0413 (10)−0.0055 (9)−0.0033 (8)−0.0102 (9)
C90.0402 (10)0.0725 (14)0.0492 (11)−0.0129 (9)−0.0039 (9)−0.0116 (10)
C100.0363 (10)0.0491 (11)0.0521 (11)−0.0078 (8)−0.0054 (8)−0.0065 (8)
C110.0484 (11)0.0654 (13)0.0408 (10)−0.0062 (9)−0.0055 (8)−0.0045 (9)
C120.118 (2)0.0786 (18)0.0577 (15)−0.0077 (16)−0.0186 (15)−0.0185 (13)
C130.0555 (13)0.0899 (17)0.0500 (12)−0.0156 (12)0.0016 (10)−0.0021 (11)
C140.0683 (15)0.0767 (17)0.0809 (17)−0.0326 (13)−0.0162 (13)0.0071 (13)
C150.0542 (15)0.168 (3)0.0741 (18)−0.0068 (17)0.0147 (13)−0.0319 (19)
C160.0635 (14)0.0744 (15)0.0670 (14)−0.0040 (11)−0.0174 (11)−0.0257 (12)
Geometric parameters (Å, °) top
C10—O3i3.295 (2)C8—C91.490 (3)
S—O4B1.463 (2)C9—C101.506 (3)
S—O4A1.464 (2)C9—H9A0.9700
S—C11.769 (2)C9—H9B0.9700
S—C161.783 (2)C11—C121.497 (3)
O1—C71.378 (2)C11—C131.501 (3)
O1—C81.382 (2)C11—H110.9800
O2—C101.332 (2)C12—H12A0.9600
O2—C111.466 (2)C12—H12B0.9600
O3—C101.199 (2)C12—H12C0.9600
C1—C81.349 (3)C13—H13A0.9600
C1—C21.448 (3)C13—H13B0.9600
C2—C71.382 (3)C13—H13C0.9600
C2—C31.412 (3)C14—H14A0.9600
C3—C41.387 (3)C14—H14B0.9600
C3—C141.502 (4)C14—H14C0.9600
C4—C51.389 (4)C15—H15A0.9600
C4—H40.9300C15—H15B0.9600
C5—C61.380 (3)C15—H15C0.9600
C5—C151.521 (3)C16—H16A0.9600
C6—C71.379 (3)C16—H16B0.9600
C6—H60.9300C16—H16C0.9600
O4B—S—O4A93.2 (8)O2—C10—C9109.90 (16)
O4B—S—C1121.5 (7)O3—C10—O3i79.52 (13)
O4A—S—C1107.56 (10)O2—C10—O3i83.17 (11)
O4B—S—C16127.3 (7)C9—C10—O3i107.38 (13)
O4A—S—C16108.31 (12)O2—C11—C12108.31 (17)
C1—S—C1697.44 (10)O2—C11—C13105.86 (16)
C7—O1—C8106.29 (15)C12—C11—C13114.3 (2)
C10—O2—C11117.50 (15)O2—C11—H11109.4
C8—C1—C2107.41 (17)C12—C11—H11109.4
C8—C1—S124.50 (15)C13—C11—H11109.4
C2—C1—S128.08 (16)C11—C12—H12A109.5
C7—C2—C3119.24 (19)C11—C12—H12B109.5
C7—C2—C1104.92 (17)H12A—C12—H12B109.5
C3—C2—C1135.8 (2)C11—C12—H12C109.5
C4—C3—C2115.5 (2)H12A—C12—H12C109.5
C4—C3—C14121.5 (2)H12B—C12—H12C109.5
C2—C3—C14123.0 (2)C11—C13—H13A109.5
C3—C4—C5124.5 (2)C11—C13—H13B109.5
C3—C4—H4117.7H13A—C13—H13B109.5
C5—C4—H4117.7C11—C13—H13C109.5
C6—C5—C4119.4 (2)H13A—C13—H13C109.5
C6—C5—C15120.6 (3)H13B—C13—H13C109.5
C4—C5—C15120.0 (3)C3—C14—H14A109.5
C7—C6—C5116.9 (2)C3—C14—H14B109.5
C7—C6—H6121.6H14A—C14—H14B109.5
C5—C6—H6121.6C3—C14—H14C109.5
O1—C7—C6124.8 (2)H14A—C14—H14C109.5
O1—C7—C2110.74 (16)H14B—C14—H14C109.5
C6—C7—C2124.4 (2)C5—C15—H15A109.5
C1—C8—O1110.62 (16)C5—C15—H15B109.5
C1—C8—C9134.01 (18)H15A—C15—H15B109.5
O1—C8—C9115.37 (17)C5—C15—H15C109.5
C8—C9—C10113.33 (16)H15A—C15—H15C109.5
C8—C9—H9A108.9H15B—C15—H15C109.5
C10—C9—H9A108.9S—C16—H16A109.5
C8—C9—H9B108.9S—C16—H16B109.5
C10—C9—H9B108.9H16A—C16—H16B109.5
H9A—C9—H9B107.7S—C16—H16C109.5
O3—C10—O2125.19 (18)H16A—C16—H16C109.5
O3—C10—C9124.88 (17)H16B—C16—H16C109.5
O4B—S—C1—C8−114.6 (9)C5—C6—C7—O1−179.9 (2)
O4A—S—C1—C8−9.3 (2)C5—C6—C7—C20.2 (3)
C16—S—C1—C8102.6 (2)C3—C2—C7—O1−178.61 (17)
O4B—S—C1—C265.6 (9)C1—C2—C7—O10.9 (2)
O4A—S—C1—C2170.83 (18)C3—C2—C7—C61.4 (3)
C16—S—C1—C2−77.2 (2)C1—C2—C7—C6−179.1 (2)
C8—C1—C2—C7−0.5 (2)C2—C1—C8—O1−0.2 (2)
S—C1—C2—C7179.39 (15)S—C1—C8—O1179.98 (13)
C8—C1—C2—C3179.0 (2)C2—C1—C8—C9179.6 (2)
S—C1—C2—C3−1.2 (4)S—C1—C8—C9−0.2 (3)
C7—C2—C3—C4−1.7 (3)C7—O1—C8—C10.7 (2)
C1—C2—C3—C4179.0 (2)C7—O1—C8—C9−179.11 (17)
C7—C2—C3—C14177.9 (2)C1—C8—C9—C10−62.5 (3)
C1—C2—C3—C14−1.5 (4)O1—C8—C9—C10117.28 (19)
C2—C3—C4—C50.6 (3)C11—O2—C10—O31.4 (3)
C14—C3—C4—C5−179.0 (2)C11—O2—C10—C9179.47 (16)
C3—C4—C5—C60.9 (4)C11—O2—C10—O3i73.42 (14)
C3—C4—C5—C15−179.2 (2)C8—C9—C10—O3−21.3 (3)
C4—C5—C6—C7−1.3 (3)C8—C9—C10—O2160.60 (17)
C15—C5—C6—C7178.8 (2)C8—C9—C10—O3i−110.50 (16)
C8—O1—C7—C6179.0 (2)C10—O2—C11—C1292.1 (2)
C8—O1—C7—C2−1.0 (2)C10—O2—C11—C13−144.89 (18)
Symmetry codes: (i) −x, −y, −z+1.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C9—H9B···Cgii0.972.993.646 (4)126
C14—H14A···O4Aiii0.962.573.504 (3)165
C15—H15C···O4Biv0.962.543.343 (5)142
C16—H16A···O4Av0.962.393.333 (3)168
C16—H16A···O4Av0.962.393.333 (3)168
Symmetry codes: (ii) x−1, y, z; (iii) x+1, y, z; (iv) −x+1, −y+1, −z; (v) −x, −y+1, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C9—H9B···Cgi0.972.993.646 (4)126
C14—H14A···O4Aii0.962.573.504 (3)165
C15—H15C···O4Biii0.962.543.343 (5)142
C16—H16A···O4Aiv0.962.393.333 (3)168
C16—H16A···O4Aiv0.962.393.333 (3)168
Symmetry codes: (i) x−1, y, z; (ii) x+1, y, z; (iii) −x+1, −y+1, −z; (iv) −x, −y+1, −z+1.
references
References top

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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, o3839.

Choi, H. D., Seo, P. J., Son, B. W. & Lee, U. (2008). Acta Cryst. E64, o2079.

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

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