Ethyl 2-(5-bromo-3-ethyl­sulfinyl-1-benzofuran-2-yl)acetate

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

doi:10.1107/S1600536809009775

. 2009 Mar 25;65(Pt 4):o838. doi: 10.1107/S1600536809009775

Ethyl 2-(5-bromo-3-ethylsulfinyl-1-benzofuran-2-yl)acetate

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

PMCID: PMC2968862 PMID: 21582557

Abstract

The title compound, C₁₄H₁₅BrO₄S, was prepared by the oxidation of ethyl 2-(5-bromo-3-ethylsulfanyl-1-benzofuran-2-yl)acetate with 3-chloroperoxybenzoic acid. The crystal structure is stabilized by aromatic π–π interactions between the benzene rings of neighbouring molecules [centroid–centroid distance = 3.814 (9) Å], and possibly by weak C—H⋯π interactions. In addition, the crystal structure exhibits three intermolecular C—H⋯O non-classical hydrogen bonds. The ethyl group bonded to carboxylate O atom is disordered over two positions, with refined site-occupancy factors of 0.686 (18) and 0.314 (18).

Related literature

For the crystal structures of similar alkyl 2-(1-benzofuran-2-yl)acetate derivatives, see: Choi et al. (2008a ▶,b ▶, 2009 ▶).

Experimental

Crystal data

C₁₄H₁₅BrO₄S
M _r = 359.23
Triclinic,
a = 8.311 (3) Å
b = 9.800 (3) Å
c = 10.621 (3) Å
α = 69.552 (5)°
β = 77.671 (6)°
γ = 66.259 (5)°
V = 739.3 (4) Å³
Z = 2
Mo Kα radiation
μ = 2.93 mm⁻¹
T = 298 K
0.30 × 0.20 × 0.10 mm

Data collection

Bruker SMART CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1999 ▶) T _min = 0.496, T _max = 0.750
5330 measured reflections
2562 independent reflections
1790 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.057
wR(F ²) = 0.168
S = 1.12
2562 reflections
191 parameters
29 restraints
H-atom parameters constrained
Δρ_max = 0.65 e Å⁻³
Δρ_min = −0.58 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); 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 datablocks global, I. DOI: 10.1107/S1600536809009775/rk2134sup1.cif

e-65-0o838-sup1.cif^{(19.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809009775/rk2134Isup2.hkl

e-65-0o838-Isup2.hkl^{(125.8KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C12A—H12B⋯Cg2ⁱ	0.96	2.92	3.85 (1)	164
C3—H3⋯O4ⁱⁱ	0.93	2.67	3.556 (8)	160
C5—H5⋯O3ⁱⁱⁱ	0.93	2.67	3.528 (9)	155
C9—H9B⋯O4^iv	0.97	2.35	3.277 (9)	161

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) . Cg2 is the centroid of the C1/C2/C7/O1/C8 furan ring.

supplementary crystallographic information

Comment

As a part of our continuing studies on the synthesis and structure of alkyl 2-(1-benzofuran-2-yl)acetate analogues, we have recently described the crystal structure of isopropyl 2-(5-bromo-3-methylsulfinyl-1-benzofuran-2-yl)acetate (Choi et al., 2008a), methyl 2-(5-bromo-3-methylsulfinyl-1-benzofuran-2-yl)acetate (Choi et al., 2008b), and ethyl 2-(3-ethylsulfinyl-5-methyl-1-benzofuran-2-yl)acetate (Choi et al., 2009). Here we report the crystal structure of the title compound, ethyl 2-(5-bromo-3-ethylsulfinyl-1-benzofuran-2-yl)acetate (Fig. 1).

The benzofuran unit is essentially planar, with a mean deviation of 0.009 (5) Å from the least-squares plane defined by the nine constituent atoms. The ethyl group bonded to carboxylate O atom is disordered over two positions with site-occupancy factors of 0.686 (18) (for atoms labelled A) and 0.314 (18) (for atoms labelled B). The molecular packing (Fig. 2) is stabilized by aromatic π–π interactions between the benzene rings of the adjacent molecules, with a Cg1···Cg1ⁱⁱ distance of 3.814 (9) Å (Cg1 is the centroid of the C2–C7 benzene ring; symmetry code as in Fig. 2). The crystal packing is further stabilized by intermolecular C—H···π interactions; a first between the methylene H atom of ethoxy group and the benzene ring of a neighbouring molecule, with C11—H11B···Cg1ⁱ, a second between the methyl H atom of ethoxy group and the furan ring of a neighbouring benzofuran fragment, with C12—H12B···Cg2ⁱ, respectively (Table 1 and Fig. 2; Cg2 is the centroid of the C1/C2/C7/O1/C8 furan ring; symmetry code as in Fig. 2). Additionally, the crystal packing exhibits weak intermolecular C—H···O nonclassical hydrogen bonds; a first between a benzene H atom and the S═O unit, a second between a benzene H atom and the C═O unit, a third between an H atom of the methylene group bonded to carboxylate C atom and the S═O unit, respectively (Table 1).

Experimental

The 77% 3-chloroperoxybenzoic acid (247 mg, 1.1 mmol) was added in small portions to a stirred solution of ethyl 2-(5-bromo-3-ethylsulfanyl-1-benzofuran-2-yl)acetate (343 mg, 1.0 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–ethyl acetate, 1:2 v/v) to afford the title compound as a colourless solid [yield 78%, m.p. 391–392 K; R_f = 0.54 (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 chloroform at room temperature. Spectroscopic analysis: ¹H NMR (CDCl₃, 400 MHz) δ 1.28 (t, J = 6.96 Hz, 3H), 1.33 (t, J = 7.32 Hz, 3H), 3.28 (q, J = 7.32 Hz, 2H), 4.05 (s, 2H), 4.21 (q, J = 6.96 Hz, 2H), 7.40 (d, J = 8.76 Hz, 1H), 7.34 (dd, J = 8.44 Hz and J = 1.84 Hz, 1H), 8.01 (s, 1H); EI–MS 360 [M+2], 358 [M⁺].