organic compounds
E)-2-[(benzofuran-2-yl)methylidene]succinate
of diethyl (aLeibniz-Institut für Katalyse e. V. an der Universität Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
*Correspondence e-mail: Thomas.Werner@catalysis.de
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.
CCDC reference: 1430813
1. 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=CR1R2, which only differ in R1 and R2 with at least one electron-withdrawing group, see: Penthala et al. (2012); Wei et al. (2011).
2. Experimental
2.1. Crystal data
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2.3. Refinement
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Data collection: APEX2 (Bruker, 2014); cell 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.
Supporting information
CCDC reference: 1430813
https://doi.org/10.1107/S2056989015019313/rz5171sup1.cif
contains datablocks I, New_Global_Publ_Block. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989015019313/rz5171Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989015019313/rz5171Isup3.cml
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 ≤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.
was performed on Merck TLC-plates with fluorescence indication (silica type 60, F254), spots were visualized using UV-light. Flash 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 over silica (SiO2) with cyclohexane/ethyl acetate (20:1 v/v) as eluents. All residues and volatiles were removed in vacuum (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═CR1R2, which only differ in R1 and R2 with at least one electron-withdrawing group, see: Penthala et al. (2012); Wei et al. (2011).
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 ≤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.
was performed on Merck TLC-plates with fluorescence indication (silica type 60, F254), spots were visualized using UV-light. Flash 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 over silica (SiO2) with cyclohexane/ethyl acetate (20:1 v/v) as eluents. All residues and volatiles were removed in vacuum ( detailsH 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 Uiso(H) fixed at 1.2 Ueq(C) for CH and CH2 and 1.5 Ueq(C) for CH3. A rotating model was used for the methyl groups.
Data collection: APEX2 (Bruker, 2014); cell
SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); 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 (Sheldrick, 2008).Fig. 1. The molecular structure of the title compound, showing the atom labelling and displacement ellipsoids drawn at 30% probability level. |
C17H18O5 | Dx = 1.298 Mg m−3 |
Mr = 302.31 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 4958 reflections |
a = 7.0974 (4) Å | θ = 2.6–28.6° |
b = 8.0898 (4) Å | µ = 0.10 mm−1 |
c = 26.9429 (15) Å | T = 150 K |
V = 1546.97 (14) Å3 | Prism, colourless |
Z = 4 | 0.46 × 0.35 × 0.20 mm |
F(000) = 640 |
Bruker APEXII CCD diffractometer | 4020 independent reflections |
Radiation source: fine-focus sealed tube | 3645 reflections with I > 2σ(I) |
Detector resolution: 8.3333 pixels mm-1 | Rint = 0.021 |
φ and ω scans | θmax = 28.8°, θmin = 1.5° |
Absorption correction: multi-scan (SADABS; Bruker, 2014) | h = −9→8 |
Tmin = 0.84, Tmax = 0.98 | k = −9→10 |
11102 measured reflections | l = −35→36 |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.035 | w = 1/[σ2(Fo2) + (0.0447P)2 + 0.2481P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.087 | (Δ/σ)max < 0.001 |
S = 1.03 | Δρmax = 0.25 e Å−3 |
4020 reflections | Δρmin = −0.16 e Å−3 |
201 parameters | Absolute structure: Flack x determined using 1441 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
0 restraints | Absolute structure parameter: −0.4 (3) |
C17H18O5 | V = 1546.97 (14) Å3 |
Mr = 302.31 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.0974 (4) Å | µ = 0.10 mm−1 |
b = 8.0898 (4) Å | T = 150 K |
c = 26.9429 (15) Å | 0.46 × 0.35 × 0.20 mm |
Bruker APEXII CCD diffractometer | 4020 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2014) | 3645 reflections with I > 2σ(I) |
Tmin = 0.84, Tmax = 0.98 | Rint = 0.021 |
11102 measured reflections |
R[F2 > 2σ(F2)] = 0.035 | H-atom parameters constrained |
wR(F2) = 0.087 | Δρmax = 0.25 e Å−3 |
S = 1.03 | Δρmin = −0.16 e Å−3 |
4020 reflections | Absolute structure: Flack x determined using 1441 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
201 parameters | Absolute structure parameter: −0.4 (3) |
0 restraints |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 1.1845 (2) | 0.8258 (2) | 0.20175 (6) | 0.0226 (3) | |
C2 | 1.3594 (3) | 0.9003 (2) | 0.20151 (7) | 0.0283 (4) | |
H2 | 1.4074 | 0.9551 | 0.1730 | 0.034* | |
C3 | 1.4612 (3) | 0.8902 (2) | 0.24552 (8) | 0.0317 (4) | |
H3 | 1.5820 | 0.9403 | 0.2473 | 0.038* | |
C4 | 1.3901 (3) | 0.8079 (2) | 0.28718 (7) | 0.0308 (4) | |
H4 | 1.4637 | 0.8033 | 0.3166 | 0.037* | |
C5 | 1.2152 (3) | 0.7334 (2) | 0.28647 (6) | 0.0282 (4) | |
H5 | 1.1677 | 0.6777 | 0.3149 | 0.034* | |
C6 | 1.1097 (2) | 0.7422 (2) | 0.24256 (6) | 0.0235 (3) | |
C7 | 0.9292 (3) | 0.6833 (2) | 0.22697 (6) | 0.0251 (3) | |
H7 | 0.8431 | 0.6206 | 0.2463 | 0.030* | |
C8 | 0.9040 (3) | 0.7338 (2) | 0.17946 (6) | 0.0237 (3) | |
C9 | 0.7443 (3) | 0.7013 (2) | 0.14801 (6) | 0.0231 (3) | |
H9 | 0.6562 | 0.6249 | 0.1613 | 0.028* | |
C10 | 0.6987 (3) | 0.7607 (2) | 0.10299 (6) | 0.0238 (3) | |
C11 | 0.8049 (3) | 0.8887 (2) | 0.07369 (6) | 0.0266 (4) | |
H11A | 0.8143 | 0.8530 | 0.0386 | 0.032* | |
H11B | 0.9342 | 0.8994 | 0.0871 | 0.032* | |
C12 | 0.7066 (3) | 1.0538 (2) | 0.07631 (6) | 0.0221 (3) | |
C13 | 0.6907 (3) | 1.3237 (2) | 0.04296 (7) | 0.0275 (4) | |
H13A | 0.7166 | 1.3773 | 0.0753 | 0.033* | |
H13B | 0.5525 | 1.3171 | 0.0384 | 0.033* | |
C14 | 0.7776 (4) | 1.4218 (3) | 0.00172 (8) | 0.0411 (5) | |
H14A | 0.9137 | 1.4307 | 0.0072 | 0.062* | |
H14B | 0.7219 | 1.5326 | 0.0010 | 0.062* | |
H14C | 0.7541 | 1.3662 | −0.0300 | 0.062* | |
C15 | 0.5193 (3) | 0.7059 (2) | 0.07940 (6) | 0.0264 (4) | |
C16 | 0.2480 (3) | 0.5350 (3) | 0.08479 (7) | 0.0333 (4) | |
H16A | 0.2709 | 0.4904 | 0.0511 | 0.040* | |
H16B | 0.1552 | 0.6259 | 0.0823 | 0.040* | |
C17 | 0.1757 (3) | 0.4019 (3) | 0.11828 (9) | 0.0423 (5) | |
H17A | 0.2665 | 0.3106 | 0.1193 | 0.063* | |
H17B | 0.0547 | 0.3612 | 0.1057 | 0.063* | |
H17C | 0.1586 | 0.4465 | 0.1518 | 0.063* | |
O1 | 1.05847 (18) | 0.82331 (16) | 0.16268 (4) | 0.0251 (3) | |
O2 | 0.77290 (18) | 1.15850 (15) | 0.04184 (4) | 0.0255 (3) | |
O3 | 0.5870 (2) | 1.09132 (17) | 0.10586 (5) | 0.0325 (3) | |
O4 | 0.42296 (19) | 0.59499 (17) | 0.10627 (5) | 0.0294 (3) | |
O5 | 0.4678 (2) | 0.75572 (19) | 0.03924 (5) | 0.0382 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0260 (8) | 0.0202 (8) | 0.0217 (7) | 0.0027 (7) | 0.0028 (6) | −0.0030 (6) |
C2 | 0.0274 (9) | 0.0263 (9) | 0.0314 (9) | −0.0004 (8) | 0.0098 (7) | −0.0024 (7) |
C3 | 0.0213 (8) | 0.0279 (9) | 0.0460 (10) | 0.0003 (8) | 0.0010 (8) | −0.0071 (8) |
C4 | 0.0287 (9) | 0.0290 (9) | 0.0349 (9) | 0.0047 (8) | −0.0086 (7) | −0.0045 (8) |
C5 | 0.0316 (9) | 0.0282 (9) | 0.0247 (8) | 0.0011 (8) | −0.0019 (7) | 0.0020 (7) |
C6 | 0.0244 (8) | 0.0210 (8) | 0.0250 (8) | 0.0004 (7) | 0.0018 (6) | −0.0007 (7) |
C7 | 0.0263 (8) | 0.0256 (8) | 0.0234 (7) | −0.0035 (8) | −0.0011 (6) | 0.0041 (7) |
C8 | 0.0273 (9) | 0.0205 (8) | 0.0232 (7) | −0.0006 (7) | 0.0013 (6) | 0.0011 (6) |
C9 | 0.0272 (8) | 0.0196 (8) | 0.0227 (7) | −0.0003 (7) | −0.0006 (6) | 0.0014 (6) |
C10 | 0.0307 (9) | 0.0203 (8) | 0.0205 (7) | 0.0061 (7) | 0.0005 (6) | −0.0011 (6) |
C11 | 0.0345 (9) | 0.0251 (9) | 0.0202 (7) | 0.0088 (8) | 0.0052 (7) | 0.0034 (7) |
C12 | 0.0271 (9) | 0.0218 (8) | 0.0176 (7) | 0.0003 (7) | −0.0019 (6) | −0.0007 (6) |
C13 | 0.0286 (9) | 0.0196 (8) | 0.0343 (9) | 0.0029 (7) | 0.0057 (7) | 0.0000 (7) |
C14 | 0.0496 (13) | 0.0254 (10) | 0.0483 (12) | 0.0056 (10) | 0.0184 (10) | 0.0096 (9) |
C15 | 0.0338 (9) | 0.0224 (9) | 0.0230 (8) | 0.0098 (7) | −0.0032 (7) | −0.0045 (6) |
C16 | 0.0259 (9) | 0.0382 (11) | 0.0356 (10) | 0.0064 (9) | −0.0093 (8) | −0.0103 (8) |
C17 | 0.0294 (10) | 0.0500 (14) | 0.0475 (12) | −0.0045 (10) | −0.0053 (9) | −0.0038 (10) |
O1 | 0.0295 (6) | 0.0262 (6) | 0.0197 (5) | −0.0021 (6) | 0.0032 (5) | 0.0010 (5) |
O2 | 0.0296 (7) | 0.0208 (6) | 0.0261 (6) | 0.0035 (5) | 0.0068 (5) | 0.0031 (5) |
O3 | 0.0433 (8) | 0.0269 (7) | 0.0272 (6) | 0.0057 (6) | 0.0126 (6) | 0.0008 (5) |
O4 | 0.0296 (7) | 0.0320 (7) | 0.0266 (6) | 0.0006 (6) | −0.0073 (5) | −0.0028 (5) |
O5 | 0.0503 (9) | 0.0375 (8) | 0.0267 (6) | 0.0075 (7) | −0.0135 (6) | 0.0018 (6) |
C1—C2 | 1.380 (3) | C11—H11A | 0.9900 |
C1—O1 | 1.381 (2) | C11—H11B | 0.9900 |
C1—C6 | 1.396 (2) | C12—O3 | 1.203 (2) |
C2—C3 | 1.391 (3) | C12—O2 | 1.342 (2) |
C2—H2 | 0.9500 | C13—O2 | 1.459 (2) |
C3—C4 | 1.399 (3) | C13—C14 | 1.498 (3) |
C3—H3 | 0.9500 | C13—H13A | 0.9900 |
C4—C5 | 1.380 (3) | C13—H13B | 0.9900 |
C4—H4 | 0.9500 | C14—H14A | 0.9800 |
C5—C6 | 1.402 (2) | C14—H14B | 0.9800 |
C5—H5 | 0.9500 | C14—H14C | 0.9800 |
C6—C7 | 1.430 (2) | C15—O5 | 1.211 (2) |
C7—C8 | 1.355 (2) | C15—O4 | 1.340 (2) |
C7—H7 | 0.9500 | C16—O4 | 1.453 (2) |
C8—O1 | 1.389 (2) | C16—C17 | 1.496 (3) |
C8—C9 | 1.439 (2) | C16—H16A | 0.9900 |
C9—C10 | 1.344 (2) | C16—H16B | 0.9900 |
C9—H9 | 0.9500 | C17—H17A | 0.9800 |
C10—C15 | 1.491 (3) | C17—H17B | 0.9800 |
C10—C11 | 1.504 (3) | C17—H17C | 0.9800 |
C11—C12 | 1.509 (2) | ||
C2—C1—O1 | 125.84 (16) | H11A—C11—H11B | 108.1 |
C2—C1—C6 | 123.88 (16) | O3—C12—O2 | 123.10 (16) |
O1—C1—C6 | 110.28 (15) | O3—C12—C11 | 125.51 (16) |
C1—C2—C3 | 115.95 (17) | O2—C12—C11 | 111.37 (14) |
C1—C2—H2 | 122.0 | O2—C13—C14 | 107.76 (15) |
C3—C2—H2 | 122.0 | O2—C13—H13A | 110.2 |
C2—C3—C4 | 121.64 (17) | C14—C13—H13A | 110.2 |
C2—C3—H3 | 119.2 | O2—C13—H13B | 110.2 |
C4—C3—H3 | 119.2 | C14—C13—H13B | 110.2 |
C5—C4—C3 | 121.42 (17) | H13A—C13—H13B | 108.5 |
C5—C4—H4 | 119.3 | C13—C14—H14A | 109.5 |
C3—C4—H4 | 119.3 | C13—C14—H14B | 109.5 |
C4—C5—C6 | 118.00 (17) | H14A—C14—H14B | 109.5 |
C4—C5—H5 | 121.0 | C13—C14—H14C | 109.5 |
C6—C5—H5 | 121.0 | H14A—C14—H14C | 109.5 |
C1—C6—C5 | 119.10 (16) | H14B—C14—H14C | 109.5 |
C1—C6—C7 | 105.72 (15) | O5—C15—O4 | 123.46 (18) |
C5—C6—C7 | 135.18 (16) | O5—C15—C10 | 122.67 (18) |
C8—C7—C6 | 107.16 (16) | O4—C15—C10 | 113.86 (15) |
C8—C7—H7 | 126.4 | O4—C16—C17 | 107.07 (16) |
C6—C7—H7 | 126.4 | O4—C16—H16A | 110.3 |
C7—C8—O1 | 111.12 (16) | C17—C16—H16A | 110.3 |
C7—C8—C9 | 127.21 (17) | O4—C16—H16B | 110.3 |
O1—C8—C9 | 121.66 (14) | C17—C16—H16B | 110.3 |
C10—C9—C8 | 130.98 (17) | H16A—C16—H16B | 108.6 |
C10—C9—H9 | 114.5 | C16—C17—H17A | 109.5 |
C8—C9—H9 | 114.5 | C16—C17—H17B | 109.5 |
C9—C10—C15 | 118.98 (17) | H17A—C17—H17B | 109.5 |
C9—C10—C11 | 126.78 (17) | C16—C17—H17C | 109.5 |
C15—C10—C11 | 114.12 (15) | H17A—C17—H17C | 109.5 |
C10—C11—C12 | 110.69 (15) | H17B—C17—H17C | 109.5 |
C10—C11—H11A | 109.5 | C1—O1—C8 | 105.71 (13) |
C12—C11—H11A | 109.5 | C12—O2—C13 | 115.07 (13) |
C10—C11—H11B | 109.5 | C15—O4—C16 | 116.38 (14) |
C12—C11—H11B | 109.5 | ||
O1—C1—C2—C3 | 178.71 (17) | C9—C10—C11—C12 | −103.4 (2) |
C6—C1—C2—C3 | −0.8 (3) | C15—C10—C11—C12 | 72.54 (18) |
C1—C2—C3—C4 | 0.5 (3) | C10—C11—C12—O3 | 15.9 (3) |
C2—C3—C4—C5 | −0.1 (3) | C10—C11—C12—O2 | −165.74 (14) |
C3—C4—C5—C6 | 0.0 (3) | C9—C10—C15—O5 | 178.99 (17) |
C2—C1—C6—C5 | 0.7 (3) | C11—C10—C15—O5 | 2.7 (2) |
O1—C1—C6—C5 | −178.89 (15) | C9—C10—C15—O4 | −2.1 (2) |
C2—C1—C6—C7 | −179.37 (17) | C11—C10—C15—O4 | −178.38 (15) |
O1—C1—C6—C7 | 1.0 (2) | C2—C1—O1—C8 | 179.37 (17) |
C4—C5—C6—C1 | −0.3 (3) | C6—C1—O1—C8 | −1.04 (19) |
C4—C5—C6—C7 | 179.9 (2) | C7—C8—O1—C1 | 0.65 (19) |
C1—C6—C7—C8 | −0.6 (2) | C9—C8—O1—C1 | −178.34 (16) |
C5—C6—C7—C8 | 179.3 (2) | O3—C12—O2—C13 | 0.7 (2) |
C6—C7—C8—O1 | 0.0 (2) | C11—C12—O2—C13 | −177.72 (14) |
C6—C7—C8—C9 | 178.90 (17) | C14—C13—O2—C12 | −178.92 (16) |
C7—C8—C9—C10 | 171.75 (19) | O5—C15—O4—C16 | −0.2 (3) |
O1—C8—C9—C10 | −9.4 (3) | C10—C15—O4—C16 | −179.08 (14) |
C8—C9—C10—C15 | −178.91 (17) | C17—C16—O4—C15 | 174.43 (16) |
C8—C9—C10—C11 | −3.1 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O3i | 0.95 | 2.47 | 3.412 (2) | 170 |
C11—H11A···O5ii | 0.99 | 2.52 | 3.458 (2) | 158 |
C11—H11B···O1 | 0.99 | 2.30 | 3.044 (2) | 131 |
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, −y+3/2, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O3i | 0.95 | 2.47 | 3.412 (2) | 170 |
C11—H11A···O5ii | 0.99 | 2.52 | 3.458 (2) | 158 |
C11—H11B···O1 | 0.99 | 2.30 | 3.044 (2) | 131 |
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, −y+3/2, −z. |
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