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Acta Cryst. (2009). E65, o2150    [ doi:10.1107/S160053680903116X ]

trans-1,2-Bis(3,5-dimethoxyphenyl)ethene

S. Ritter, J.-M. Neudörfl, J. Velder and H.-G. Schmalz

Abstract top

The title compound, C18H20O4, was prepared in high yield from 3,5-dimethoxystyrene via a Ru-catalysed homo-olefin metathesis. Exclusive formation of the E-configurated isomer was observed. Interestingly, one symmetric unit contains two molecules adopting an s-syn-anti and and an all-s-anti conformation.

Comment top

In recent years, polyhydroxylated stilbenes such as resveratrol have gained a tremendous importance especially due to their potential for the prevention and therapy of cancer (Aggarwal et al. (2004), Wolter et al. (2002), Fremont (2000), Jang et al. (1997)). In the course of our own research in the field of bioactive stilbenes (Wieder et al. (2001)) we were able to develop a highly efficient synthetic route towards symmetrically as well as unsymmetrically substituted E-stilbenes applying a Ru-catalyzed metathesis strategy (Velder et al. (2006)). Alternative strategies for the synthesis of stilbenes are based on Wittig-type olefinations or Heck couplings (Kim et al. (2002), Lion et al. (2005), Botella et al. (2004), Reetz et al. (1998). One of the compounds prepared was the title compound trans-1,2-bis-(3,5-dimethoxyphenyl)ethene. The asymmetric unit contains two molecules, A and B, both of which exhibit a center of symmetry (figure 1). The 3,5-dimethoxy groups of molecule B all adopt a s-anti configuration, whereas in molecule A, a s-syn as well as a s-anti conformation is found on both sides. Zhang and co-workers reported the same observation on a related structure (Yin et al., 2002). The torsion angles between the benzene ring planes in molecule A are 0.2 (3)° (C1a—C1—C2—C3), which gives the molecule a planar shape. Molecule B, in contrast, adopts a slightly twisted conformation with a torsion angle of 7.0 (2)° (C10b—C10—C11—C12). The molecules form slightly twisted pseudo-layers which are arranged along the b axis (Fig. 2). In figure 3, two of those pseudo-layers are shown from the top view (with the front layer being displayed in dark and the retral layer in light green).

Related literature top

For the preparation of differently substituted stilbenes using a Ru-catalysed metathesis strategy, see: Velder et al. (2006). Alternative methodologies for the synthesis of oxy-functionalized stilbenes using Wittig-type olefinations or Heck couplings have been described by Kim et al. (2002), Lion et al. (2005), Botella et al. (2004) and Reetz et al. (1998). For the bioactivity of various stilbenes with a focus on their anticancer activity, see: Aggarwal et al. (2004); Wolter et al. (2002); Fremont (2000); Jang et al. (1997); Wieder et al. (2001). For related structures and syntheses see: Yin et al. (2002); Uda et al. (2002).

Experimental top

In a glove-box (Labmaster 130, mBraun), the catalyst (Grubbs-II, 2 mol %) was weighted into a 25 ml Schlenk tube, which was then sealed with a rubber septum. This was then taken out of the box, connected to an Ar-vacuum double manifold and equipped with a reflux condenser under argon. A solution of 3,5-dimethoxy-styrene (1 mmol) in CH2Cl2 (10 ml) was then added via syringe and the resulting solution was refluxed for 1.5 h under argon. After allowing the reaction mixture to cool to room temperature, the solvent was evaporated in vacuo and the crude product was purified by flash chromatography (SiO2, cyclohexane/ ethyl acetate = 10:1) to give 138 mg (0.46 mmol; 92%) of the homo metathesis product (1). mp. 142 °C (Uda et al., 2002: 141–144 °C). 1H NMR (300 MHz, CDCl3): δ = 3.81 (s, 6H, OCH3), 6.4 (t, 1H, J = 2.1 Hz,H-4), 6.67 (d, 2H, J = 2.1 Hz, H-2, H-6), 7.00 (s, 1H, H-7); 13C NMR (75 MHz, CDCl3): δ = 55.4 (OCH3), 100.2 (C-4), 104.7 (C-2, C-6), 129.2 (C-7), 139.2 (C-1), 161.0 (C-3, C-5); HRMS, calcd for C18H20O4 (M+) 300.1361, found 300.136.

Computing details top

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SCHAKAL99 (Keller 1999); software used to prepare material for publication: PLATON (Spek, 2009) and enCIFer (Allen et al., 2004).

Figures top
[Figure 1] Fig. 1. A view of (1). Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. View of the unit cell along the b axis.
[Figure 3] Fig. 3. Top view of two pseudo layers.
trans-1,2-Bis(3,5-dimethoxyphenyl)ethene top
Crystal data top
C18H20O4F(000) = 640
Mr = 300.34Dx = 1.301 Mg m−3
Monoclinic, P21/cMelting point: 142 K
Hall symbol: -P 2ybcMo Kα radiation, λ = 0.71073 Å
a = 7.1954 (3) ÅCell parameters from 7687 reflections
b = 9.4203 (4) Åθ = 2.3–27.0°
c = 22.6762 (5) ŵ = 0.09 mm−1
β = 93.783 (2)°T = 100 K
V = 1533.71 (10) Å3Needle, colourless
Z = 40.4 × 0.2 × 0.2 mm
Data collection top
Nonius KappaCCD
diffractometer		2142 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.041
graphiteθmax = 27.0°, θmin = 2.3°
φ and ω scansh = −6→9
7687 measured reflectionsk = −12→10
3320 independent reflectionsl = −25→28
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)] = 0.055Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.150H-atom parameters constrained
S = 1.03 w = 1/[σ2(Fo2) + (0.0722P)2 + 0.274P]
where P = (Fo2 + 2Fc2)/3
3320 reflections(Δ/σ)max < 0.001
207 parametersΔρmax = 0.24 e Å−3
0 restraintsΔρmin = −0.24 e Å−3
Crystal data top
C18H20O4V = 1533.71 (10) Å3
Mr = 300.34Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.1954 (3) ŵ = 0.09 mm−1
b = 9.4203 (4) ÅT = 100 K
c = 22.6762 (5) Å0.4 × 0.2 × 0.2 mm
β = 93.783 (2)°
Data collection top
Nonius KappaCCD
diffractometer		2142 reflections with I > 2σ(I)
7687 measured reflectionsRint = 0.041
3320 independent reflectionsθmax = 27.0°
Refinement top
R[F2 > 2σ(F2)] = 0.055H-atom parameters constrained
wR(F2) = 0.150Δρmax = 0.24 e Å−3
S = 1.03Δρmin = −0.24 e Å−3
3320 reflectionsAbsolute structure: ?
207 parametersFlack parameter: ?
0 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. The coordinates of the hydrogenatoms are constrained, and the U values of the H atoms are constrained relative to the Ueq of the atom the hydrogen binds to (1.2 for CH and CH2, 1.5 for CH3).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.16550 (18)0.11969 (13)0.29039 (5)0.0322 (4)
O20.11990 (18)0.52539 (13)0.41414 (6)0.0346 (4)
C10.0096 (2)0.07001 (18)0.49846 (8)0.0272 (4)
H1−0.00990.12200.53340.033*
C20.0575 (2)0.15286 (19)0.44674 (8)0.0256 (4)
C30.0903 (2)0.0879 (2)0.39261 (8)0.0268 (4)
H30.0831−0.01230.38850.032*
C40.1329 (2)0.17169 (19)0.34549 (8)0.0259 (4)
C50.1450 (2)0.31913 (19)0.35017 (8)0.0275 (4)
H50.17480.37530.31730.033*
C60.1123 (2)0.38210 (19)0.40394 (8)0.0267 (4)
C70.0691 (2)0.2989 (2)0.45200 (8)0.0274 (4)
H70.04750.34280.48860.033*
C80.1666 (3)−0.03060 (19)0.28252 (8)0.0312 (5)
H8A0.2575−0.07340.31130.047*
H8B0.2006−0.05300.24240.047*
H8C0.0424−0.06870.28840.047*
C90.1455 (3)0.6156 (2)0.36467 (9)0.0359 (5)
H9A0.26450.59330.34820.054*
H9B0.14570.71490.37750.054*
H9C0.04370.60030.33440.054*
O30.31579 (18)0.49045 (14)0.21349 (5)0.0360 (4)
O40.33384 (18)0.03486 (14)0.13362 (6)0.0392 (4)
C100.4952 (2)0.43244 (19)0.00794 (8)0.0299 (4)
H100.52840.3637−0.02020.040 (6)*
C110.4382 (2)0.3787 (2)0.06489 (8)0.0273 (4)
C120.4051 (2)0.4693 (2)0.11208 (8)0.0289 (4)
H120.42060.56890.10830.020 (5)*
C130.3493 (2)0.4114 (2)0.16439 (8)0.0288 (5)
C140.3246 (2)0.2665 (2)0.17034 (8)0.0303 (5)
H140.28490.22850.20620.047 (6)*
C150.3581 (2)0.1774 (2)0.12378 (8)0.0296 (5)
C160.4155 (2)0.2328 (2)0.07095 (8)0.0293 (5)
H160.43910.17110.03920.030 (5)*
C170.3394 (3)0.6410 (2)0.20992 (9)0.0373 (5)
H17A0.46790.66250.20110.056*
H17B0.31280.68450.24770.056*
H17C0.25360.67920.17850.056*
C180.3671 (3)−0.0593 (2)0.08589 (9)0.0386 (5)
H18A0.2853−0.03400.05120.058*
H18B0.3415−0.15710.09760.058*
H18C0.4974−0.05140.07610.058*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0478 (8)0.0283 (7)0.0216 (7)−0.0022 (6)0.0118 (6)0.0006 (6)
O20.0487 (8)0.0268 (8)0.0291 (8)−0.0033 (6)0.0080 (6)0.0032 (6)
C10.0288 (9)0.0332 (10)0.0200 (9)0.0004 (8)0.0046 (7)−0.0001 (8)
C20.0249 (9)0.0291 (11)0.0227 (10)0.0000 (8)0.0014 (7)0.0040 (8)
C30.0280 (10)0.0261 (10)0.0265 (11)−0.0010 (7)0.0028 (8)0.0025 (8)
C40.0256 (9)0.0307 (11)0.0216 (10)0.0010 (8)0.0034 (7)0.0005 (8)
C50.0291 (10)0.0288 (11)0.0252 (10)−0.0006 (8)0.0053 (8)0.0073 (8)
C60.0269 (10)0.0249 (10)0.0281 (11)−0.0020 (8)0.0008 (8)0.0025 (8)
C70.0294 (10)0.0295 (10)0.0235 (10)−0.0007 (8)0.0040 (8)0.0012 (8)
C80.0372 (11)0.0303 (11)0.0266 (11)−0.0027 (8)0.0056 (8)−0.0018 (8)
C90.0444 (12)0.0292 (11)0.0342 (12)−0.0031 (9)0.0046 (9)0.0078 (9)
O30.0443 (8)0.0397 (8)0.0251 (8)−0.0033 (6)0.0097 (6)0.0002 (6)
O40.0489 (9)0.0328 (8)0.0370 (8)−0.0008 (6)0.0108 (7)0.0093 (6)
C100.0324 (10)0.0344 (10)0.0232 (10)−0.0013 (9)0.0044 (8)0.0020 (9)
C110.0248 (9)0.0339 (11)0.0234 (10)−0.0013 (8)0.0019 (7)0.0060 (8)
C120.0285 (10)0.0308 (11)0.0275 (11)−0.0019 (8)0.0020 (8)0.0048 (8)
C130.0252 (10)0.0396 (12)0.0218 (10)−0.0017 (8)0.0027 (7)0.0028 (8)
C140.0294 (10)0.0383 (12)0.0237 (10)−0.0005 (8)0.0051 (8)0.0093 (9)
C150.0266 (10)0.0320 (11)0.0304 (11)−0.0018 (8)0.0023 (8)0.0090 (9)
C160.0282 (10)0.0339 (12)0.0259 (11)−0.0001 (8)0.0025 (8)0.0018 (8)
C170.0434 (12)0.0404 (12)0.0287 (12)−0.0045 (10)0.0078 (9)−0.0043 (9)
C180.0412 (12)0.0330 (12)0.0423 (13)−0.0009 (9)0.0070 (10)0.0054 (10)
Geometric parameters (Å, °) top
O1—C41.376 (2)O3—C131.374 (2)
O1—C81.427 (2)O3—C171.432 (2)
O2—C61.370 (2)O4—C151.375 (2)
O2—C91.429 (2)O4—C181.432 (2)
C1—C1i1.328 (3)C10—C10ii1.326 (4)
C1—C21.469 (2)C10—C111.470 (2)
C1—H10.9500C10—H100.9500
C2—C71.383 (3)C11—C161.392 (3)
C2—C31.405 (2)C11—C121.401 (3)
C3—C41.379 (2)C12—C131.389 (2)
C3—H30.9500C12—H120.9500
C4—C51.395 (3)C13—C141.384 (3)
C5—C61.390 (2)C14—C151.382 (3)
C5—H50.9500C14—H140.9500
C6—C71.394 (2)C15—C161.394 (2)
C7—H70.9500C16—H160.9500
C8—H8A0.9800C17—H17A0.9800
C8—H8B0.9800C17—H17B0.9800
C8—H8C0.9800C17—H17C0.9800
C9—H9A0.9800C18—H18A0.9800
C9—H9B0.9800C18—H18B0.9800
C9—H9C0.9800C18—H18C0.9800
C4—O1—C8117.99 (13)C13—O3—C17117.61 (14)
C6—O2—C9117.31 (15)C15—O4—C18116.97 (14)
C1i—C1—C2126.9 (2)C10ii—C10—C11126.3 (2)
C1i—C1—H1116.6C10ii—C10—H10116.9
C2—C1—H1116.6C11—C10—H10116.9
C7—C2—C3119.73 (16)C16—C11—C12119.91 (16)
C7—C2—C1118.41 (16)C16—C11—C10117.89 (17)
C3—C2—C1121.87 (16)C12—C11—C10122.19 (17)
C4—C3—C2119.10 (17)C13—C12—C11119.14 (17)
C4—C3—H3120.5C13—C12—H12120.4
C2—C3—H3120.5C11—C12—H12120.4
O1—C4—C3124.02 (16)O3—C13—C14115.15 (16)
O1—C4—C5114.20 (15)O3—C13—C12123.76 (17)
C3—C4—C5121.77 (16)C14—C13—C12121.09 (17)
C6—C5—C4118.58 (16)C15—C14—C13119.63 (16)
C6—C5—H5120.7C15—C14—H14120.2
C4—C5—H5120.7C13—C14—H14120.2
O2—C6—C5124.17 (16)O4—C15—C14116.03 (16)
O2—C6—C7115.49 (16)O4—C15—C16123.58 (17)
C5—C6—C7120.34 (17)C14—C15—C16120.38 (17)
C2—C7—C6120.47 (17)C11—C16—C15119.84 (17)
C2—C7—H7119.8C11—C16—H16120.1
C6—C7—H7119.8C15—C16—H16120.1
O1—C8—H8A109.5O3—C17—H17A109.5
O1—C8—H8B109.5O3—C17—H17B109.5
H8A—C8—H8B109.5H17A—C17—H17B109.5
O1—C8—H8C109.5O3—C17—H17C109.5
H8A—C8—H8C109.5H17A—C17—H17C109.5
H8B—C8—H8C109.5H17B—C17—H17C109.5
O2—C9—H9A109.5O4—C18—H18A109.5
O2—C9—H9B109.5O4—C18—H18B109.5
H9A—C9—H9B109.5H18A—C18—H18B109.5
O2—C9—H9C109.5O4—C18—H18C109.5
H9A—C9—H9C109.5H18A—C18—H18C109.5
H9B—C9—H9C109.5H18B—C18—H18C109.5
C1i—C1—C2—C7179.3 (2)C10ii—C10—C11—C16172.5 (2)
C1i—C1—C2—C3−0.3 (3)C10ii—C10—C11—C12−6.9 (4)
C7—C2—C3—C4−0.2 (3)C16—C11—C12—C13−0.2 (3)
C1—C2—C3—C4179.35 (16)C10—C11—C12—C13179.18 (17)
C8—O1—C4—C3−4.1 (2)C17—O3—C13—C14179.90 (16)
C8—O1—C4—C5176.49 (15)C17—O3—C13—C120.3 (3)
C2—C3—C4—O1−179.24 (16)C11—C12—C13—O3179.04 (16)
C2—C3—C4—C50.2 (3)C11—C12—C13—C14−0.5 (3)
O1—C4—C5—C6179.31 (15)O3—C13—C14—C15−178.83 (15)
C3—C4—C5—C6−0.2 (3)C12—C13—C14—C150.8 (3)
C9—O2—C6—C56.2 (3)C18—O4—C15—C14179.78 (16)
C9—O2—C6—C7−173.96 (15)C18—O4—C15—C16−1.1 (3)
C4—C5—C6—O2179.99 (16)C13—C14—C15—O4178.80 (16)
C4—C5—C6—C70.2 (3)C13—C14—C15—C16−0.3 (3)
C3—C2—C7—C60.2 (3)C12—C11—C16—C150.6 (3)
C1—C2—C7—C6−179.33 (16)C10—C11—C16—C15−178.75 (16)
O2—C6—C7—C2179.95 (15)O4—C15—C16—C11−179.43 (16)
C5—C6—C7—C2−0.2 (3)C14—C15—C16—C11−0.4 (3)
Symmetry codes: (i) −x, −y, −z+1; (ii) −x+1, −y+1, −z.
references
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