2-(5-Bromo-3-isopropyl­sulfanyl-1-benzofuran-2-yl)acetic acid

Pil Ja Seo; Hong Dae Choi; Byeng Wha Son; Uk Lee

doi:10.1107/S1600536811052160

. 2011 Dec 10;68(Pt 1):o58. doi: 10.1107/S1600536811052160

2-(5-Bromo-3-isopropylsulfanyl-1-benzofuran-2-yl)acetic acid

Pil Ja Seo ^a, Hong Dae Choi ^a, Byeng Wha Son ^b, Uk Lee ^b,^*

PMCID: PMC3254414 PMID: 22259558

Abstract

The title compound, C₁₃H₁₃BrO₃S, was prepared by alkaline hydrolysis of ethyl 2-(5-bromo-3-isopropylsulfanyl-1-benzofuran-2-yl)acetate. In the crystal, the carboxyl groups are involved in intermolecular O—H⋯O hydrogen bonds, which link the molecules into dimers. These dimers are further packed into stacks along the c axis by intermolecular C—H⋯π interactions, and by slipped π–π interactions between the furan rings of adjacent molecules [centroid–centroid distance = 3.472 (2) Å, interplanar distance = 3.398 (2) Å and slippage = 0.713 (2) Å].

Related literature

For the pharmacological activity of benzofuran compounds, see: Aslam et al. (2009 ▶); Galal et al. (2009 ▶); Khan et al. (2005 ▶). For natural products with benzofuran rings, see: Akgul & Anil (2003 ▶); Soekamto et al. (2003 ▶). For the crystal structures of related compounds, see: Choi et al. (2009a ▶,b ▶).

Experimental

Crystal data

C₁₃H₁₃BrO₃S
M _r = 329.20
Triclinic,
a = 7.4689 (3) Å
b = 9.9449 (4) Å
c = 10.0653 (4) Å
α = 98.415 (2)°
β = 102.146 (2)°
γ = 110.341 (3)°
V = 665.38 (5) Å³
Z = 2
Mo Kα radiation
μ = 3.24 mm⁻¹
T = 296 K
0.24 × 0.17 × 0.10 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.510, T _max = 0.738
11869 measured reflections
3082 independent reflections
2731 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.024
wR(F ²) = 0.064
S = 1.03
3082 reflections
169 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.52 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; 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.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811052160/bg2430sup1.cif

e-68-00o58-sup1.cif^{(22.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811052160/bg2430Isup2.hkl

e-68-00o58-Isup2.hkl^{(151.2KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811052160/bg2430Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg2 is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2O⋯O3ⁱ	0.74 (3)	1.90 (3)	2.640 (2)	177 (3)
C9—H9B⋯Cg2ⁱⁱ	0.97	2.72 (1)	3.376 (2)	126

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Symmetry codes: (i) Inline graphic ; (ii) .

supplementary crystallographic information

Comment

Substituted benzofuran derivatives have attracted considerable interest in view of their valuable pharmacological properties such as antibacterial and antifungal, antitumor and antiviral, and antimicrobial activities (Aslam et al. , 2009, Galal et al. , 2009, Khan et al. , 2005). These benzofuran derivatives occur in a wide range of natural products (Akgul & Anil, 2003; Soekamto et al. , 2003). As a part of our ongoing study of 2-(5-bromo-1-benzofuran-2-yl) acetic acid analogues (Choi et al. , 2009a,b), we report herein the crystal structure of the title compound.

In the title molecule (Fig. 1), the benzofuran unit is essentially planar, with a mean deviation of 0.007 (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 (Table 1, first entry & Fig. 2), which link the molecules into centrosymmetric dimers. These dimers are further packed into stacks along the c axis by an intermolecular C—H···π interaction between a methylene H atom and the benzene ring (Table 1, second entry & Fig. 2), and by a weak slipped π–π interaction between the furan rings of adjacent molecules, with a Cg1···Cg1ⁱⁱ distance of 3.742 (2) Å and an interplanar distance of 3.398 (2) Å resulting in a slippage of 0.713 (2) Å (Fig. 2, Cg1 is the centroid of the C1-C2-C7-O1-C8 furan ring, (ii) -x+1, -y+1, -z.).

Experimental

Ethyl 2-(5-bromo-3-isopropylsulfanyl-1-benzofuran-2-yl)acetate (428 mg, 1.2 mmol) was added to a solution of potassium hydroxide (337 mg. 6 mmol) in water (10 ml) and methanol (10 ml), and the mixture was refluxed for 5 h, then cooled. Water (10 ml) 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 at reduced pressure. The residue was purified by column chromatography (ethyl acetate) to afford the title compound as a colorless solid [yield 86%, m.p. 432–433 K; R_f = 0.51 (ethyl acetate)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a solution of the title compound in benzene at room temperature.