organic compounds
2,4-Dimethoxy-6-[(E)-2-(4-methoxyphenyl)ethenyl]benzaldehyde
aSchool of Medical Engineering, Hefei University of Technology, Hefei 230009, People's Republic of China
*Correspondence e-mail: ruanbf@hfut.edu.cn
There are two conformationally similar molecules in the 18H18O4, in which the dihedral angles between the benzene rings are 23.54 (12) and 31.11 (12)°. In the crystal, C—H⋯π interactions (minimum H⋯ring centroid distance = 2.66 Å) link the molecules into a layered structure extending down a.
of he title compound, CRelated literature
The title compound is a derivative of the natural product resveratrol (trans-3,4,5-trihydroxystilbene). For background to resveratrol, see: Jang et al. (1997); Orsini et al. (1997); Pettit et al. (2002). For standard bond lengths and angles, see: Boumendjel et al. (2008). For the synthesis of the title compound, see: Huang et al. (2007).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 2000); cell SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S1600536813007964/zs2252sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813007964/zs2252Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536813007964/zs2252Isup3.ps
Supporting information file. DOI: https://doi.org/10.1107/S1600536813007964/zs2252Isup4.mol
Supporting information file. DOI: https://doi.org/10.1107/S1600536813007964/zs2252Isup5.cml
Title compound was synthesized according to the reported method (Huang et al., 2007). Crystals suitable for X-ray structure analysis were obtained by slow evaporation of a solution of the title compound in a petroleum ether/ dichloromethane mixture (1:1, v/v) at room temperature.
All the H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H distances of 0.93–0.96 Å, and with Uiso(H) = 1.2Ueq(carrier) or 1.5Ueq(methyl groups).
Resveratrol (trans-3,4,,5-trihydroxystilbene), a naturally occurring phytoalexin present in medicinal plants, grape skin, peanuts and red wine, has attracted a great deal of attention because it has been suggested as a possible cancer chemopreventive agent on the basis of its inhibitory effects on tumor initiation, promotion, and progression (Jang et al., 1997; Orsini et al., 1997; Pettit et al., 2002). In order to discover novel antitumor agents with high efficiency, a broad spectrum and safety, several series of derivatives of resveratrol were prepared in our laboratory. As an important intermediate, the title compound 2,4-dimethoxy-6-[(E)-2-(4-methoxyphenyl)ethenyl]benzaldehyde, was synthesized by the reaction of resveratrol using the Vilslmeier reaction and herein we report the crystal structure.
The title compound, C18 H18 O4, crystallizes in the triclinic
P-1 with two independent molecules in the (Fig. 1). All bond lengths are within normal ranges (Boumendjel et al., 2008). The C10—C11 and C28—C29 bond lengths [1.319 (3) and 1.323 (3) Å] are consistent with the expected value for a C—C double bond and similarly, the C7—O1 and C25—O5 bond lengths [1.196 (3) and 1.210 (3) Å] are consistent with the expected value for a carbonyl C—O double bond. The dihedral angle between the two phenyl rings in each are 23.54 (12)° [C1–C6 (ring 1) and C12–C17) (ring 2)] and 31.11 (12)° [C19–C24 (ring 3) and C30–C35 (ring 4)]. As such, the structural differences between the two molecules in the title compound are only marginal.In the crystal, the two molecules associate through C—H···pi stacking interactions [C14—H14···Cg(4)i; C17—H···Cg(4)ii; C32—H···Cg(2)iii; C35—H···Cg(2)iv: H···Cg = 2.88, 2.76, 2.82, 2.66 Å respectively] [for symmetry codes: (i) -x + 1, -y + 1, -z + 1; (ii) -x + 1, -y, -z + 1; (iii) x, y, z; (iv) x + 1, y, z]. Intermolecular methoxy C26—H···O8v interactions [3.041 (4) Å] across an inversion centre generate a sheet structure (Fig. 2) [for symmetry code (v): -x + 2, -y, -z + 1]. Present also in the structure are intramolecular C—H···O interactions between the aldehyde and ethylenic donors and methoxy O-atom acceptors (Table 1).
The title compound is a derivative of the natural product resveratrol (trans-3,4,5-trihydroxystilbene). For background to resveratrol, see: Jang et al. (1997); Orsini et al. (1997); Pettit et al. (2002). For standard bond lengths and angles, see: Boumendjel et al. (2008). For the synthesis of the title compound, see: Huang et al. (2007).
Data collection: SMART (Bruker, 2000); cell
SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. The molecular structure and atom numbering scheme for the two independent molecules of the title compound in the asymmetric unit, showing 30% probability displacement ellipsoids. | |
Fig. 2. The layered structure of title compound formed through C—H···pi stacking interactions. Non-interactive H-atoms are omitted. |
C18H18O4 | Z = 4 |
Mr = 298.32 | F(000) = 632 |
Triclinic, P1 | Dx = 1.308 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71069 Å |
a = 9.292 (5) Å | Cell parameters from 1909 reflections |
b = 9.448 (5) Å | θ = 2.2–26.7° |
c = 17.547 (5) Å | µ = 0.09 mm−1 |
α = 84.097 (5)° | T = 298 K |
β = 84.040 (5)° | Block, colourless |
γ = 83.315 (5)° | 0.30 × 0.20 × 0.20 mm |
V = 1515.3 (12) Å3 |
Bruker SMART CCD area-detector diffractometer | 5272 independent reflections |
Radiation source: fine-focus sealed tube | 3060 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.039 |
φ and ω scans | θmax = 25.0°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | h = −11→10 |
Tmin = 0.973, Tmax = 0.982 | k = −11→11 |
10535 measured reflections | l = −20→19 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.048 | H-atom parameters constrained |
wR(F2) = 0.168 | w = 1/[σ2(Fo2) + (0.1P)2 + 0.699P] where P = (Fo2 + 2Fc2)/3 |
S = 0.79 | (Δ/σ)max < 0.001 |
5272 reflections | Δρmax = 0.15 e Å−3 |
404 parameters | Δρmin = −0.18 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.017 (2) |
C18H18O4 | γ = 83.315 (5)° |
Mr = 298.32 | V = 1515.3 (12) Å3 |
Triclinic, P1 | Z = 4 |
a = 9.292 (5) Å | Mo Kα radiation |
b = 9.448 (5) Å | µ = 0.09 mm−1 |
c = 17.547 (5) Å | T = 298 K |
α = 84.097 (5)° | 0.30 × 0.20 × 0.20 mm |
β = 84.040 (5)° |
Bruker SMART CCD area-detector diffractometer | 5272 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | 3060 reflections with I > 2σ(I) |
Tmin = 0.973, Tmax = 0.982 | Rint = 0.039 |
10535 measured reflections |
R[F2 > 2σ(F2)] = 0.048 | 0 restraints |
wR(F2) = 0.168 | H-atom parameters constrained |
S = 0.79 | Δρmax = 0.15 e Å−3 |
5272 reflections | Δρmin = −0.18 e Å−3 |
404 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O4 | 0.14160 (19) | 0.29091 (17) | 0.65390 (9) | 0.0490 (5) | |
O8 | 0.6445 (2) | 0.3074 (2) | 0.65049 (10) | 0.0584 (5) | |
O2 | 0.6991 (2) | −0.0498 (2) | 0.13171 (10) | 0.0641 (6) | |
O6 | 1.2124 (2) | −0.0612 (2) | 0.13477 (10) | 0.0663 (6) | |
C12 | 0.3000 (2) | 0.2119 (2) | 0.42976 (13) | 0.0377 (6) | |
C15 | 0.1936 (2) | 0.2736 (2) | 0.57966 (13) | 0.0368 (6) | |
O5 | 0.9275 (2) | 0.3222 (2) | 0.00997 (10) | 0.0698 (6) | |
O1 | 0.4129 (2) | 0.3330 (2) | 0.00836 (10) | 0.0674 (6) | |
C33 | 0.6939 (3) | 0.2778 (2) | 0.57720 (13) | 0.0393 (6) | |
C29 | 0.8934 (3) | 0.1922 (2) | 0.35458 (13) | 0.0413 (6) | |
H29 | 0.9886 | 0.1486 | 0.3536 | 0.050* | |
C13 | 0.2388 (2) | 0.3479 (2) | 0.44573 (13) | 0.0400 (6) | |
H13 | 0.2332 | 0.4200 | 0.4055 | 0.048* | |
C11 | 0.3571 (3) | 0.1739 (3) | 0.35295 (14) | 0.0444 (6) | |
H11 | 0.4007 | 0.0807 | 0.3497 | 0.053* | |
C30 | 0.8207 (3) | 0.2192 (2) | 0.43039 (13) | 0.0367 (6) | |
C35 | 0.8980 (3) | 0.1892 (2) | 0.49504 (13) | 0.0404 (6) | |
H35 | 0.9942 | 0.1490 | 0.4892 | 0.048* | |
C31 | 0.6761 (3) | 0.2748 (2) | 0.44293 (13) | 0.0394 (6) | |
H31 | 0.6201 | 0.2922 | 0.4013 | 0.047* | |
C16 | 0.2576 (3) | 0.1382 (2) | 0.56550 (13) | 0.0401 (6) | |
H16 | 0.2659 | 0.0670 | 0.6060 | 0.048* | |
C4 | 0.5278 (3) | 0.1016 (3) | 0.20863 (14) | 0.0463 (6) | |
H4 | 0.5554 | 0.0505 | 0.2539 | 0.056* | |
C19 | 0.9651 (3) | 0.2384 (3) | 0.07433 (14) | 0.0491 (7) | |
C24 | 0.8850 (3) | 0.2751 (3) | 0.14382 (14) | 0.0436 (6) | |
C3 | 0.5943 (3) | 0.0623 (3) | 0.13922 (15) | 0.0471 (6) | |
O7 | 0.7066 (2) | 0.4560 (2) | 0.19247 (11) | 0.0734 (6) | |
C32 | 0.6124 (3) | 0.3051 (2) | 0.51476 (13) | 0.0410 (6) | |
H32 | 0.5156 | 0.3435 | 0.5211 | 0.049* | |
C34 | 0.8365 (3) | 0.2172 (3) | 0.56693 (14) | 0.0443 (6) | |
H34 | 0.8908 | 0.1954 | 0.6090 | 0.053* | |
C23 | 0.9194 (3) | 0.1940 (2) | 0.21264 (13) | 0.0421 (6) | |
C20 | 1.0740 (3) | 0.1273 (3) | 0.07344 (15) | 0.0522 (7) | |
H20 | 1.1262 | 0.1047 | 0.0273 | 0.063* | |
C1 | 0.4531 (3) | 0.2517 (3) | 0.07286 (14) | 0.0473 (6) | |
C5 | 0.4200 (3) | 0.2160 (3) | 0.21234 (13) | 0.0430 (6) | |
C2 | 0.5590 (3) | 0.1378 (3) | 0.07091 (14) | 0.0516 (7) | |
H2 | 0.6062 | 0.1118 | 0.0243 | 0.062* | |
C28 | 0.8397 (3) | 0.2227 (2) | 0.28713 (14) | 0.0444 (6) | |
H28 | 0.7443 | 0.2654 | 0.2869 | 0.053* | |
C21 | 1.1053 (3) | 0.0493 (3) | 0.14175 (15) | 0.0481 (6) | |
C14 | 0.1858 (3) | 0.3803 (2) | 0.51919 (13) | 0.0395 (6) | |
H14 | 0.1453 | 0.4726 | 0.5280 | 0.047* | |
C6 | 0.3793 (3) | 0.2931 (3) | 0.14320 (14) | 0.0441 (6) | |
O3 | 0.1938 (3) | 0.4673 (3) | 0.19099 (12) | 0.0913 (8) | |
C17 | 0.3091 (3) | 0.1078 (2) | 0.49209 (13) | 0.0396 (6) | |
H17 | 0.3509 | 0.0157 | 0.4837 | 0.047* | |
C22 | 1.0291 (3) | 0.0813 (3) | 0.21013 (14) | 0.0475 (6) | |
H22 | 1.0513 | 0.0267 | 0.2554 | 0.057* | |
C10 | 0.3540 (3) | 0.2567 (3) | 0.28771 (14) | 0.0492 (7) | |
H10 | 0.3060 | 0.3484 | 0.2896 | 0.059* | |
C27 | 0.7704 (3) | 0.3951 (3) | 0.13975 (16) | 0.0545 (7) | |
H27 | 0.7437 | 0.4282 | 0.0909 | 0.065* | |
C18 | 0.0775 (3) | 0.4283 (3) | 0.67268 (16) | 0.0655 (9) | |
H18A | 0.1483 | 0.4957 | 0.6614 | 0.098* | |
H18B | 0.0444 | 0.4241 | 0.7265 | 0.098* | |
H18C | −0.0035 | 0.4581 | 0.6429 | 0.098* | |
C9 | 0.2627 (3) | 0.4111 (3) | 0.13893 (17) | 0.0593 (8) | |
H9 | 0.2396 | 0.4467 | 0.0898 | 0.071* | |
C25 | 1.0115 (4) | 0.2970 (3) | −0.06044 (15) | 0.0743 (9) | |
H25A | 1.1114 | 0.3084 | −0.0557 | 0.111* | |
H25B | 0.9758 | 0.3642 | −0.1008 | 0.111* | |
H25C | 1.0042 | 0.2014 | −0.0725 | 0.111* | |
C8 | 0.7351 (4) | −0.1367 (3) | 0.19987 (16) | 0.0722 (9) | |
H8A | 0.7697 | −0.0791 | 0.2346 | 0.108* | |
H8B | 0.8097 | −0.2118 | 0.1868 | 0.108* | |
H8C | 0.6502 | −0.1779 | 0.2241 | 0.108* | |
C36 | 0.5076 (3) | 0.3858 (3) | 0.66358 (16) | 0.0632 (8) | |
H36A | 0.5030 | 0.4724 | 0.6297 | 0.095* | |
H36B | 0.4933 | 0.4091 | 0.7160 | 0.095* | |
H36C | 0.4329 | 0.3295 | 0.6540 | 0.095* | |
C26 | 1.2461 (4) | −0.1482 (3) | 0.20355 (16) | 0.0727 (9) | |
H26A | 1.2762 | −0.0899 | 0.2394 | 0.109* | |
H26B | 1.3232 | −0.2215 | 0.1914 | 0.109* | |
H26C | 1.1613 | −0.1917 | 0.2260 | 0.109* | |
C7 | 0.4947 (4) | 0.3057 (3) | −0.06241 (15) | 0.0728 (9) | |
H7A | 0.5953 | 0.3159 | −0.0586 | 0.109* | |
H7B | 0.4589 | 0.3728 | −0.1028 | 0.109* | |
H7C | 0.4855 | 0.2101 | −0.0738 | 0.109* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O4 | 0.0641 (12) | 0.0468 (10) | 0.0339 (10) | 0.0028 (9) | −0.0014 (9) | −0.0061 (8) |
O8 | 0.0587 (12) | 0.0752 (13) | 0.0359 (11) | 0.0159 (10) | −0.0024 (9) | −0.0079 (9) |
O2 | 0.0753 (14) | 0.0640 (12) | 0.0428 (11) | 0.0229 (11) | 0.0027 (10) | 0.0008 (9) |
O6 | 0.0766 (14) | 0.0687 (13) | 0.0430 (11) | 0.0281 (11) | 0.0005 (10) | −0.0008 (9) |
C12 | 0.0364 (13) | 0.0377 (13) | 0.0383 (14) | −0.0038 (10) | −0.0014 (11) | −0.0023 (10) |
C15 | 0.0364 (13) | 0.0404 (13) | 0.0336 (14) | −0.0026 (11) | −0.0040 (11) | −0.0048 (10) |
O5 | 0.0817 (14) | 0.0805 (14) | 0.0353 (11) | 0.0236 (11) | 0.0019 (10) | 0.0076 (10) |
O1 | 0.0782 (14) | 0.0788 (14) | 0.0348 (11) | 0.0208 (11) | 0.0007 (10) | 0.0044 (9) |
C33 | 0.0438 (15) | 0.0380 (13) | 0.0347 (14) | −0.0009 (11) | −0.0027 (11) | −0.0016 (10) |
C29 | 0.0428 (14) | 0.0406 (13) | 0.0391 (15) | −0.0001 (11) | −0.0019 (12) | −0.0034 (11) |
C13 | 0.0452 (15) | 0.0379 (13) | 0.0353 (14) | −0.0010 (11) | −0.0065 (11) | 0.0039 (11) |
C11 | 0.0488 (15) | 0.0438 (14) | 0.0392 (15) | −0.0006 (12) | −0.0005 (12) | −0.0062 (12) |
C30 | 0.0395 (14) | 0.0331 (12) | 0.0371 (14) | −0.0032 (10) | −0.0033 (11) | −0.0022 (10) |
C35 | 0.0334 (13) | 0.0438 (14) | 0.0440 (15) | −0.0008 (11) | −0.0076 (11) | −0.0035 (11) |
C31 | 0.0423 (15) | 0.0405 (13) | 0.0350 (14) | −0.0011 (11) | −0.0105 (11) | 0.0018 (10) |
C16 | 0.0483 (15) | 0.0328 (12) | 0.0385 (14) | −0.0036 (11) | −0.0077 (12) | 0.0028 (10) |
C4 | 0.0518 (16) | 0.0506 (15) | 0.0336 (14) | 0.0021 (13) | −0.0040 (12) | 0.0007 (11) |
C19 | 0.0574 (17) | 0.0488 (15) | 0.0383 (15) | 0.0006 (13) | −0.0054 (13) | 0.0030 (12) |
C24 | 0.0491 (15) | 0.0428 (14) | 0.0368 (15) | 0.0013 (12) | −0.0022 (12) | −0.0033 (11) |
C3 | 0.0511 (16) | 0.0482 (15) | 0.0399 (15) | 0.0024 (13) | −0.0018 (12) | −0.0050 (12) |
O7 | 0.0889 (16) | 0.0706 (13) | 0.0507 (13) | 0.0321 (12) | −0.0004 (11) | −0.0093 (10) |
C32 | 0.0351 (14) | 0.0435 (14) | 0.0421 (15) | 0.0026 (11) | −0.0037 (11) | −0.0012 (11) |
C34 | 0.0406 (15) | 0.0536 (15) | 0.0386 (15) | 0.0018 (12) | −0.0113 (12) | −0.0037 (12) |
C23 | 0.0475 (15) | 0.0406 (13) | 0.0377 (14) | −0.0028 (12) | −0.0022 (12) | −0.0052 (11) |
C20 | 0.0574 (17) | 0.0561 (16) | 0.0388 (16) | 0.0063 (14) | 0.0032 (13) | −0.0062 (13) |
C1 | 0.0549 (16) | 0.0515 (15) | 0.0335 (14) | −0.0017 (13) | −0.0058 (12) | 0.0026 (12) |
C5 | 0.0472 (15) | 0.0472 (14) | 0.0351 (14) | −0.0050 (12) | −0.0052 (12) | −0.0047 (11) |
C2 | 0.0611 (18) | 0.0555 (16) | 0.0344 (15) | 0.0036 (14) | 0.0016 (13) | −0.0035 (12) |
C28 | 0.0486 (15) | 0.0427 (14) | 0.0403 (15) | 0.0015 (12) | −0.0029 (12) | −0.0050 (11) |
C21 | 0.0515 (16) | 0.0460 (15) | 0.0441 (16) | 0.0047 (12) | −0.0025 (13) | −0.0051 (12) |
C14 | 0.0439 (14) | 0.0323 (12) | 0.0412 (15) | 0.0031 (11) | −0.0073 (11) | −0.0031 (11) |
C6 | 0.0463 (15) | 0.0476 (15) | 0.0369 (15) | −0.0012 (12) | −0.0023 (12) | −0.0034 (11) |
O3 | 0.1072 (18) | 0.0979 (17) | 0.0522 (14) | 0.0503 (15) | 0.0014 (13) | −0.0063 (12) |
C17 | 0.0452 (14) | 0.0311 (12) | 0.0414 (15) | −0.0005 (10) | −0.0030 (11) | −0.0036 (10) |
C22 | 0.0546 (16) | 0.0511 (15) | 0.0346 (15) | 0.0019 (13) | −0.0033 (12) | −0.0035 (12) |
C10 | 0.0545 (16) | 0.0524 (15) | 0.0390 (15) | 0.0053 (13) | −0.0042 (12) | −0.0078 (12) |
C27 | 0.0600 (18) | 0.0560 (17) | 0.0437 (16) | 0.0056 (14) | −0.0046 (14) | −0.0004 (13) |
C18 | 0.088 (2) | 0.0557 (17) | 0.0473 (18) | 0.0156 (16) | 0.0027 (16) | −0.0153 (14) |
C9 | 0.0634 (19) | 0.0636 (18) | 0.0450 (17) | 0.0100 (15) | 0.0002 (15) | −0.0005 (14) |
C25 | 0.091 (2) | 0.086 (2) | 0.0361 (17) | 0.0159 (19) | 0.0019 (16) | 0.0065 (15) |
C8 | 0.087 (2) | 0.0664 (19) | 0.0513 (19) | 0.0222 (17) | −0.0011 (16) | 0.0105 (15) |
C36 | 0.0549 (18) | 0.076 (2) | 0.0524 (18) | 0.0074 (15) | 0.0112 (14) | −0.0083 (15) |
C26 | 0.084 (2) | 0.070 (2) | 0.0526 (19) | 0.0292 (17) | −0.0030 (16) | 0.0004 (15) |
C7 | 0.091 (2) | 0.080 (2) | 0.0374 (17) | 0.0167 (18) | 0.0009 (16) | 0.0060 (15) |
O4—C15 | 1.361 (3) | C3—C2 | 1.380 (3) |
O4—C18 | 1.420 (3) | O7—C27 | 1.206 (3) |
O8—C33 | 1.365 (3) | C32—H32 | 0.9300 |
O8—C36 | 1.405 (3) | C34—H34 | 0.9300 |
O2—C3 | 1.360 (3) | C23—C22 | 1.386 (3) |
O2—C8 | 1.426 (3) | C23—C28 | 1.468 (3) |
O6—C21 | 1.362 (3) | C20—C21 | 1.380 (3) |
O6—C26 | 1.430 (3) | C20—H20 | 0.9300 |
C12—C13 | 1.387 (3) | C1—C2 | 1.372 (3) |
C12—C17 | 1.396 (3) | C1—C6 | 1.417 (3) |
C12—C11 | 1.461 (3) | C5—C6 | 1.412 (3) |
C15—C16 | 1.382 (3) | C5—C10 | 1.468 (3) |
C15—C14 | 1.388 (3) | C2—H2 | 0.9300 |
O5—C19 | 1.363 (3) | C28—H28 | 0.9300 |
O5—C25 | 1.418 (3) | C21—C22 | 1.372 (3) |
O1—C1 | 1.361 (3) | C14—H14 | 0.9300 |
O1—C7 | 1.418 (3) | C6—C9 | 1.463 (4) |
C33—C32 | 1.382 (3) | O3—C9 | 1.194 (3) |
C33—C34 | 1.383 (3) | C17—H17 | 0.9300 |
C29—C28 | 1.324 (3) | C22—H22 | 0.9300 |
C29—C30 | 1.461 (3) | C10—H10 | 0.9300 |
C29—H29 | 0.9300 | C27—H27 | 0.9300 |
C13—C14 | 1.383 (3) | C18—H18A | 0.9600 |
C13—H13 | 0.9300 | C18—H18B | 0.9600 |
C11—C10 | 1.319 (3) | C18—H18C | 0.9600 |
C11—H11 | 0.9300 | C9—H9 | 0.9300 |
C30—C31 | 1.389 (3) | C25—H25A | 0.9600 |
C30—C35 | 1.392 (3) | C25—H25B | 0.9600 |
C35—C34 | 1.368 (3) | C25—H25C | 0.9600 |
C35—H35 | 0.9300 | C8—H8A | 0.9600 |
C31—C32 | 1.379 (3) | C8—H8B | 0.9600 |
C31—H31 | 0.9300 | C8—H8C | 0.9600 |
C16—C17 | 1.374 (3) | C36—H36A | 0.9600 |
C16—H16 | 0.9300 | C36—H36B | 0.9600 |
C4—C3 | 1.373 (3) | C36—H36C | 0.9600 |
C4—C5 | 1.387 (3) | C26—H26A | 0.9600 |
C4—H4 | 0.9300 | C26—H26B | 0.9600 |
C19—C20 | 1.371 (3) | C26—H26C | 0.9600 |
C19—C24 | 1.414 (3) | C7—H7A | 0.9600 |
C24—C23 | 1.407 (3) | C7—H7B | 0.9600 |
C24—C27 | 1.464 (3) | C7—H7C | 0.9600 |
C15—O4—C18 | 118.68 (19) | C1—C2—C3 | 119.0 (2) |
C33—O8—C36 | 119.0 (2) | C1—C2—H2 | 120.5 |
C3—O2—C8 | 117.7 (2) | C3—C2—H2 | 120.5 |
C21—O6—C26 | 117.2 (2) | C29—C28—C23 | 124.8 (2) |
C13—C12—C17 | 116.8 (2) | C29—C28—H28 | 117.6 |
C13—C12—C11 | 123.9 (2) | C23—C28—H28 | 117.6 |
C17—C12—C11 | 119.2 (2) | O6—C21—C22 | 124.1 (2) |
O4—C15—C16 | 115.8 (2) | O6—C21—C20 | 114.9 (2) |
O4—C15—C14 | 124.9 (2) | C22—C21—C20 | 121.0 (2) |
C16—C15—C14 | 119.3 (2) | C13—C14—C15 | 119.3 (2) |
C19—O5—C25 | 117.6 (2) | C13—C14—H14 | 120.4 |
C1—O1—C7 | 117.6 (2) | C15—C14—H14 | 120.4 |
O8—C33—C32 | 124.7 (2) | C5—C6—C1 | 118.2 (2) |
O8—C33—C34 | 115.8 (2) | C5—C6—C9 | 124.4 (2) |
C32—C33—C34 | 119.5 (2) | C1—C6—C9 | 117.4 (2) |
C28—C29—C30 | 127.5 (2) | C16—C17—C12 | 121.5 (2) |
C28—C29—H29 | 116.2 | C16—C17—H17 | 119.2 |
C30—C29—H29 | 116.2 | C12—C17—H17 | 119.2 |
C14—C13—C12 | 122.5 (2) | C21—C22—C23 | 120.9 (2) |
C14—C13—H13 | 118.8 | C21—C22—H22 | 119.6 |
C12—C13—H13 | 118.8 | C23—C22—H22 | 119.6 |
C10—C11—C12 | 127.4 (2) | C11—C10—C5 | 125.5 (2) |
C10—C11—H11 | 116.3 | C11—C10—H10 | 117.3 |
C12—C11—H11 | 116.3 | C5—C10—H10 | 117.3 |
C31—C30—C35 | 116.5 (2) | O7—C27—C24 | 127.4 (3) |
C31—C30—C29 | 123.9 (2) | O7—C27—H27 | 116.3 |
C35—C30—C29 | 119.6 (2) | C24—C27—H27 | 116.3 |
C34—C35—C30 | 121.9 (2) | O4—C18—H18A | 109.5 |
C34—C35—H35 | 119.0 | O4—C18—H18B | 109.5 |
C30—C35—H35 | 119.0 | H18A—C18—H18B | 109.5 |
C32—C31—C30 | 122.4 (2) | O4—C18—H18C | 109.5 |
C32—C31—H31 | 118.8 | H18A—C18—H18C | 109.5 |
C30—C31—H31 | 118.8 | H18B—C18—H18C | 109.5 |
C17—C16—C15 | 120.6 (2) | O3—C9—C6 | 127.8 (3) |
C17—C16—H16 | 119.7 | O3—C9—H9 | 116.1 |
C15—C16—H16 | 119.7 | C6—C9—H9 | 116.1 |
C3—C4—C5 | 121.1 (2) | O5—C25—H25A | 109.5 |
C3—C4—H4 | 119.4 | O5—C25—H25B | 109.5 |
C5—C4—H4 | 119.4 | H25A—C25—H25B | 109.5 |
O5—C19—C20 | 123.4 (2) | O5—C25—H25C | 109.5 |
O5—C19—C24 | 115.3 (2) | H25A—C25—H25C | 109.5 |
C20—C19—C24 | 121.3 (2) | H25B—C25—H25C | 109.5 |
C23—C24—C19 | 118.3 (2) | O2—C8—H8A | 109.5 |
C23—C24—C27 | 123.8 (2) | O2—C8—H8B | 109.5 |
C19—C24—C27 | 117.9 (2) | H8A—C8—H8B | 109.5 |
O2—C3—C4 | 123.9 (2) | O2—C8—H8C | 109.5 |
O2—C3—C2 | 114.9 (2) | H8A—C8—H8C | 109.5 |
C4—C3—C2 | 121.1 (2) | H8B—C8—H8C | 109.5 |
C31—C32—C33 | 119.3 (2) | O8—C36—H36A | 109.5 |
C31—C32—H32 | 120.3 | O8—C36—H36B | 109.5 |
C33—C32—H32 | 120.3 | H36A—C36—H36B | 109.5 |
C35—C34—C33 | 120.2 (2) | O8—C36—H36C | 109.5 |
C35—C34—H34 | 119.9 | H36A—C36—H36C | 109.5 |
C33—C34—H34 | 119.9 | H36B—C36—H36C | 109.5 |
C22—C23—C24 | 119.3 (2) | O6—C26—H26A | 109.5 |
C22—C23—C28 | 118.8 (2) | O6—C26—H26B | 109.5 |
C24—C23—C28 | 121.9 (2) | H26A—C26—H26B | 109.5 |
C19—C20—C21 | 119.2 (2) | O6—C26—H26C | 109.5 |
C19—C20—H20 | 120.4 | H26A—C26—H26C | 109.5 |
C21—C20—H20 | 120.4 | H26B—C26—H26C | 109.5 |
O1—C1—C2 | 122.8 (2) | O1—C7—H7A | 109.5 |
O1—C1—C6 | 115.6 (2) | O1—C7—H7B | 109.5 |
C2—C1—C6 | 121.5 (2) | H7A—C7—H7B | 109.5 |
C4—C5—C6 | 119.0 (2) | O1—C7—H7C | 109.5 |
C4—C5—C10 | 119.5 (2) | H7A—C7—H7C | 109.5 |
C6—C5—C10 | 121.6 (2) | H7B—C7—H7C | 109.5 |
C18—O4—C15—C16 | 178.6 (2) | C7—O1—C1—C6 | 173.1 (2) |
C18—O4—C15—C14 | −1.7 (3) | C3—C4—C5—C6 | −0.2 (4) |
C36—O8—C33—C32 | −7.7 (4) | C3—C4—C5—C10 | −178.5 (2) |
C36—O8—C33—C34 | 171.8 (2) | O1—C1—C2—C3 | 179.1 (2) |
C17—C12—C13—C14 | −1.4 (3) | C6—C1—C2—C3 | −0.2 (4) |
C11—C12—C13—C14 | −179.9 (2) | O2—C3—C2—C1 | 179.2 (2) |
C13—C12—C11—C10 | −3.6 (4) | C4—C3—C2—C1 | −1.5 (4) |
C17—C12—C11—C10 | 177.9 (2) | C30—C29—C28—C23 | 179.3 (2) |
C28—C29—C30—C31 | 4.4 (4) | C22—C23—C28—C29 | 27.9 (4) |
C28—C29—C30—C35 | −175.4 (2) | C24—C23—C28—C29 | −153.8 (2) |
C31—C30—C35—C34 | −2.1 (3) | C26—O6—C21—C22 | 0.1 (4) |
C29—C30—C35—C34 | 177.7 (2) | C26—O6—C21—C20 | −178.1 (3) |
C35—C30—C31—C32 | 2.7 (3) | C19—C20—C21—O6 | 178.3 (2) |
C29—C30—C31—C32 | −177.0 (2) | C19—C20—C21—C22 | 0.1 (4) |
O4—C15—C16—C17 | 177.7 (2) | C12—C13—C14—C15 | 0.0 (4) |
C14—C15—C16—C17 | −2.0 (3) | O4—C15—C14—C13 | −178.0 (2) |
C25—O5—C19—C20 | −3.6 (4) | C16—C15—C14—C13 | 1.7 (3) |
C25—O5—C19—C24 | 175.3 (2) | C4—C5—C6—C1 | −1.4 (4) |
O5—C19—C24—C23 | −179.3 (2) | C10—C5—C6—C1 | 176.9 (2) |
C20—C19—C24—C23 | −0.3 (4) | C4—C5—C6—C9 | 176.9 (2) |
O5—C19—C24—C27 | 1.1 (4) | C10—C5—C6—C9 | −4.8 (4) |
C20—C19—C24—C27 | −179.9 (2) | O1—C1—C6—C5 | −177.7 (2) |
C8—O2—C3—C4 | 4.0 (4) | C2—C1—C6—C5 | 1.6 (4) |
C8—O2—C3—C2 | −176.8 (3) | O1—C1—C6—C9 | 3.8 (4) |
C5—C4—C3—O2 | −179.1 (2) | C2—C1—C6—C9 | −176.8 (2) |
C5—C4—C3—C2 | 1.7 (4) | C15—C16—C17—C12 | 0.6 (4) |
C30—C31—C32—C33 | −0.9 (3) | C13—C12—C17—C16 | 1.0 (3) |
O8—C33—C32—C31 | 177.8 (2) | C11—C12—C17—C16 | 179.7 (2) |
C34—C33—C32—C31 | −1.7 (3) | O6—C21—C22—C23 | −178.8 (2) |
C30—C35—C34—C33 | −0.4 (4) | C20—C21—C22—C23 | −0.7 (4) |
O8—C33—C34—C35 | −177.2 (2) | C24—C23—C22—C21 | 0.8 (4) |
C32—C33—C34—C35 | 2.3 (4) | C28—C23—C22—C21 | 179.1 (2) |
C19—C24—C23—C22 | −0.3 (4) | C12—C11—C10—C5 | 176.5 (2) |
C27—C24—C23—C22 | 179.3 (2) | C4—C5—C10—C11 | −19.5 (4) |
C19—C24—C23—C28 | −178.6 (2) | C6—C5—C10—C11 | 162.3 (3) |
C27—C24—C23—C28 | 1.0 (4) | C23—C24—C27—O7 | 12.8 (5) |
O5—C19—C20—C21 | 179.3 (3) | C19—C24—C27—O7 | −167.6 (3) |
C24—C19—C20—C21 | 0.4 (4) | C5—C6—C9—O3 | 6.5 (5) |
C7—O1—C1—C2 | −6.2 (4) | C1—C6—C9—O3 | −175.2 (3) |
Cg2 and Cg4 are the centroids of the C12–C17 and C30–C35 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···O1 | 0.93 | 2.29 | 2.681 (4) | 105 |
C10—H10···O3 | 0.93 | 2.25 | 2.863 (4) | 123 |
C27—H27···O5 | 0.93 | 2.31 | 2.681 (4) | 103 |
C28—H28···O7 | 0.93 | 2.34 | 2.861 (3) | 115 |
C14—H14···Cg4i | 0.93 | 2.88 | 3.597 (3) | 135 |
C17—H14···Cg4ii | 0.93 | 2.76 | 3.471 (3) | 134 |
C32—H14···Cg2 | 0.93 | 2.82 | 3.530 (3) | 135 |
C15—H14···Cg2iii | 0.93 | 2.66 | 3.371 (3) | 134 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y+1, −z+1; (iii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C18H18O4 |
Mr | 298.32 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 298 |
a, b, c (Å) | 9.292 (5), 9.448 (5), 17.547 (5) |
α, β, γ (°) | 84.097 (5), 84.040 (5), 83.315 (5) |
V (Å3) | 1515.3 (12) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.30 × 0.20 × 0.20 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2000) |
Tmin, Tmax | 0.973, 0.982 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10535, 5272, 3060 |
Rint | 0.039 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.048, 0.168, 0.79 |
No. of reflections | 5272 |
No. of parameters | 404 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.15, −0.18 |
Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
Cg2 and Cg4 are the centroids of the C12–C17 and C30–C35 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C14—H14···Cg4i | 0.93 | 2.88 | 3.597 (3) | 135 |
C17—H14···Cg4ii | 0.93 | 2.76 | 3.471 (3) | 134 |
C32—H14···Cg2 | 0.93 | 2.82 | 3.530 (3) | 135 |
C15—H14···Cg2iii | 0.93 | 2.66 | 3.371 (3) | 134 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y+1, −z+1; (iii) x+1, y, z. |
Acknowledgements
This work was supported by Anhui Provincial Natural Science Foundation (grant No. 1308085MB18).
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Resveratrol (trans-3,4,,5-trihydroxystilbene), a naturally occurring phytoalexin present in medicinal plants, grape skin, peanuts and red wine, has attracted a great deal of attention because it has been suggested as a possible cancer chemopreventive agent on the basis of its inhibitory effects on tumor initiation, promotion, and progression (Jang et al., 1997; Orsini et al., 1997; Pettit et al., 2002). In order to discover novel antitumor agents with high efficiency, a broad spectrum and safety, several series of derivatives of resveratrol were prepared in our laboratory. As an important intermediate, the title compound 2,4-dimethoxy-6-[(E)-2-(4-methoxyphenyl)ethenyl]benzaldehyde, was synthesized by the reaction of resveratrol using the Vilslmeier reaction and herein we report the crystal structure.
The title compound, C18 H18 O4, crystallizes in the triclinic space group P-1 with two independent molecules in the asymmetric unit (Fig. 1). All bond lengths are within normal ranges (Boumendjel et al., 2008). The C10—C11 and C28—C29 bond lengths [1.319 (3) and 1.323 (3) Å] are consistent with the expected value for a C—C double bond and similarly, the C7—O1 and C25—O5 bond lengths [1.196 (3) and 1.210 (3) Å] are consistent with the expected value for a carbonyl C—O double bond. The dihedral angle between the two phenyl rings in each are 23.54 (12)° [C1–C6 (ring 1) and C12–C17) (ring 2)] and 31.11 (12)° [C19–C24 (ring 3) and C30–C35 (ring 4)]. As such, the structural differences between the two molecules in the title compound are only marginal.
In the crystal, the two molecules associate through C—H···pi stacking interactions [C14—H14···Cg(4)i; C17—H···Cg(4)ii; C32—H···Cg(2)iii; C35—H···Cg(2)iv: H···Cg = 2.88, 2.76, 2.82, 2.66 Å respectively] [for symmetry codes: (i) -x + 1, -y + 1, -z + 1; (ii) -x + 1, -y, -z + 1; (iii) x, y, z; (iv) x + 1, y, z]. Intermolecular methoxy C26—H···O8v interactions [3.041 (4) Å] across an inversion centre generate a sheet structure (Fig. 2) [for symmetry code (v): -x + 2, -y, -z + 1]. Present also in the structure are intramolecular C—H···O interactions between the aldehyde and ethylenic donors and methoxy O-atom acceptors (Table 1).