Crystal structure of diethyl (E)-2-[(benzo­furan-2-yl)methyl­idene]succinate

Marie-Luis Schirmer; Anke Spannenberg; Thomas Werner

doi:10.1107/S2056989015019313

. 2015 Oct 24;71(Pt 11):o872. doi: 10.1107/S2056989015019313

Crystal structure of diethyl (E)-2-[(benzofuran-2-yl)methylidene]succinate

Marie-Luis Schirmer ^a, Anke Spannenberg ^a, Thomas Werner ^a,^*

PMCID: PMC4645082 PMID: 26594572

Abstract

The title compound, C₁₇H₁₈O₅, was synthesized by a base-free catalytic Wittig reaction. The molecule consists of a diethyl itaconate unit, which is connected via the C=C double bond to a benzofuran moiety. The benzofuran ring system (r.m.s. deviation = 0.007 Å) forms dihedral angles of 79.58 (4) and 12.12 (10)° with the mean planes through the cis and trans ethoxycarbonyl groups, respectively. An intramolecular C—H⋯O hydrogen bond involving the O atom of the benzofuran moiety is observed. In the crystal, molecules are linked into ribbons running parallel to the b axis by C—H⋯O hydrogen bonds.

Keywords: crystal structure, benzofuran, diene, Wittig reaction, hydrogen bonding

Related literature

For the synthesis of the title compound and related structures, see: Schirmer et al. (2015 ▸). For related crystal structures of similar compounds corresponding to (benzofuran)-CH=CR ¹ R ², which only differ in R ¹ and R ² with at least one electron-withdrawing group, see: Penthala et al. (2012 ▸); Wei et al. (2011 ▸). graphic file with name e-71-0o872-scheme1.jpg

Experimental

Crystal data

C₁₇H₁₈O₅
M _r = 302.31
Orthorhombic,
a = 7.0974 (4) Å
b = 8.0898 (4) Å
c = 26.9429 (15) Å
V = 1546.97 (14) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 150 K
0.46 × 0.35 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2014 ▸) T _min = 0.84, T _max = 0.98
11102 measured reflections
4020 independent reflections
3645 reflections with I > 2σ(I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.035
wR(F ²) = 0.087
S = 1.03
4020 reflections
201 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Data collection: APEX2 (Bruker, 2014 ▸); cell refinement: SAINT (Bruker, 2013 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015 ▸); molecular graphics: XP in SHELXTL (Sheldrick, 2008 ▸); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S2056989015019313/rz5171sup1.cif

e-71-0o872-sup1.cif^{(339.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015019313/rz5171Isup2.hkl

e-71-0o872-Isup2.hkl^{(320.5KB, hkl)}

Click here for additional data file.^{(6.1KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015019313/rz5171Isup3.cml

Click here for additional data file.^{(1.3MB, tif)}

. DOI: 10.1107/S2056989015019313/rz5171fig1.tif

The molecular structure of the title compound, showing the atom labelling and displacement ellipsoids drawn at 30% probability level.

CCDC reference: 1430813

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C2H2O3ⁱ	0.95	2.47	3.412(2)	170
C11H11AO5ⁱⁱ	0.99	2.52	3.458(2)	158
C11H11BO1	0.99	2.30	3.044(2)	131

Open in a new tab

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

supplementary crystallographic information

S1. Synthesis and crystallization

Diethyl (E)-2-(benzofuran-2-ylmethylene) succinate was prepared as previously described by Schirmer et al. (2015). All reagents were purchased from commercial sources and used as received without further purification. The reaction was performed in 5 mL Wheaton screw-top V-Vials® with solid-top cap. The vial was dried in an oven at 120°C before use. Toluene was freshly distilled from sodium/benzophenone. Thin layer chromatography was performed on Merck TLC-plates with fluorescence indication (silica type 60, F254), spots were visualized using UV-light. Flash chromatography was performed using silica with a grain size of 40–63 µm from Macherey-Nagel. Benzofuran-2-carbaldehyde (151 mg, 1.03 mmol) was dissolved in toluene (2 mL). Diethyl maleate (197 mg, 1.14 mmol), tri-n-butylphosphine (11 mg, 0.054 mmol) and phenylsilane (113 mg, 1.04 mmol) were added successively to the solution. After stirring for 24 h at 125°C, the reaction mixture was cooled to ambient temperature. The crude product was purified by column chromatography over silica (SiO₂) with cyclohexane/ethyl acetate (20:1 v/v) as eluents. All residues and volatiles were removed in vacuum (≤1 mbar, 60°C) to afford the olefination product (219 mg, 0.724 mmol, yield 70%, E/Z = 95:5) as colourless solid. Single crystals could be obtained by slow evaporation of a petroleum/dichloromethane (4:1 v/v) solution.

S2. Refinement

H atoms were placed in idealized positions with d(C—H) = 0.95 Å (CH), 0.99 Å (CH₂), 0.98 Å (CH₃) and refined using a riding model with U_iso(H) fixed at 1.2 U_eq(C) for CH and CH₂ and 1.5 U_eq(C) for CH₃. A rotating model was used for the methyl groups.