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access(E)-2-Methoxy-9-(2-methoxy-9H-xanthen-9-ylidene)-9H-xanthene
aDepartment of Chemistry, University of Science and Technology of China, Hefei 230026, People's Republic of China
*Correspondence e-mail: qhsong@ustc.edu.cn
The title compound, C28H20O4, was synthesized by a bimolecular Zn–HCl reduction in glacial acetic acid using the methoxy-substituted xanthone as a starting material. The shows that the 2,2′-methoxybixanthenylidene unit is an E-type conformation anti-folded conformer. The molecule lies on an inversion center. The methoxy group is almost coplanar with the attached benzene ring, with a C—O—C—C torsion angle of 179.38 (14)°.
Related literature
For background to dixanthylidenes, see: Korenstein et al. (1976![[Korenstein, R., Muszkat, K. A., Slifkin, M. A. & Fischer, E. (1976). J. Chem. Soc. Perkin Trans. 2, pp. 438-443.]](../../../../../../logos/arrows/e_arr.gif "Korenstein, R., Muszkat, K. A., Slifkin, M. A. & Fischer, E. (1976). J. Chem. Soc. Perkin Trans. 2, pp. 438-443.")
); Agranat & Tapuhi (1979); Mao et al. (2011). For related structures, see: Mills & Nyburg (1963); Shi et al. (2012).
![[Scheme 1]](zq2201scheme1.gif)
Experimental
Crystal data
|
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97.
Supporting information
contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536813017297/zq2201sup1.cif
Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813017297/zq2201Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536813017297/zq2201Isup3.cml
2-Methoxyxanthone (8.8 mmol) was refluxed overnight in oxalyl dichloride (10 ml). The excess of oxalyl dichloride was removed, and the residue was dissolved in freshly distilled p-xylene (30 ml). Activated Cu powder (3.81 g, 60.0 mmol) was added and refluxed for 7 h with occasional shaking. The reaction solution was filtered, and the filter was concentrated and crystallized to give the title compound (Mao et al., 2011). The title compound was dissolved in 10 ml of THF, and then adding 2 ml of toluene to the solution. The mixture solution was placed in a open flask upon standing at 45–50° C for 5 days, single crystals appeared, and were separated from the solvent by decantation.
All hydrogen positions were calculated after each cycle of using a riding model, with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C) for aromatic H atoms, and with C—H = 0.96 Å and Uiso(H) = 1.5Ueq(C) for methyl H atoms.
The 2,2'-substituted bixanthenylidenes have two conformers (Z, E), which are unstable at room temperature (Korenstein et al., 1976). Z, E isomerization, with a low activation energy of 2,2'-disubstituted bixanthenylidenes, occurs easily at room temperature, and the ratio of Z/E in solution depends on the bulkiness of the the 2 and 2' substituents (Agranat & Tapuhi, 1979), 1:1.13 for the title compound. The of the title compound shows that the E-type conformer lies on an inversion center located in the middle of the C8=C8i double bond (symmetry code: i = -x+1, -y+1, -z+1). The methoxy group is almost coplanar with the phenyl ring with a C1—O1—C2—C3 torsion angle of 179.38 (14) degrees (Fig.1). For related structures, see: Mills & Nyburg (1963); Shi et al. (2012).
For background to dixanthylidenes, see: Korenstein et al. (1976); Agranat & Tapuhi (1979); Mao et al. (2011). For related structures, see: Mills & Nyburg (1963); Shi et al. (2012).
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell CrysAlis PRO (Oxford Diffraction, 2007); data reduction: CrysAlis PRO (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
![[Figure 1]](./zq2201fig1thm.gif) | Fig. 1. The structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme (symmetry code: i = -x+1, -y+1, -z+1). |
| C28H20O4 | F(000) = 440 |
| Mr = 420.28 | Dx = 1.337 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 2041 reflections |
| a = 8.5699 (7) Å | θ = 2.7–29.1° |
| b = 7.5200 (6) Å | µ = 0.09 mm−1 |
| c = 16.6101 (18) Å | T = 291 K |
| β = 102.682 (7)° | Block, colourless |
| V = 1044.33 (16) Å3 | 0.42 × 0.40 × 0.32 mm |
| Z = 2 |
| Oxford Diffraction Gemini S Ultra diffractometer | 2205 independent reflections |
| Radiation source: Enhance (Mo) X-ray Source | 1264 reflections with I > 2σ(I) |
| Graphite monochromator | Rint = 0.029 |
| Detector resolution: 15.9149 pixels mm-1 | θmax = 26.7°, θmin = 3.0° |
| ω scans | h = −10→7 |
| Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) | k = −7→9 |
| Tmin = 0.964, Tmax = 0.972 | l = −21→21 |
| 6419 measured reflections |
| Refinement on F2 | 0 restraints |
| Least-squares matrix: full | H-atom parameters constrained |
| R[F2 > 2σ(F2)] = 0.037 | w = 1/[σ2(Fo2) + (0.0079P)2 + 0.150P] where P = (Fo2 + 2Fc2)/3 |
| wR(F2) = 0.060 | (Δ/σ)max < 0.001 |
| S = 1.00 | Δρmax = 0.16 e Å−3 |
| 2205 reflections | Δρmin = −0.17 e Å−3 |
| 146 parameters |
| C28H20O4 | V = 1044.33 (16) Å3 |
| Mr = 420.28 | Z = 2 |
| Monoclinic, P21/c | Mo Kα radiation |
| a = 8.5699 (7) Å | µ = 0.09 mm−1 |
| b = 7.5200 (6) Å | T = 291 K |
| c = 16.6101 (18) Å | 0.42 × 0.40 × 0.32 mm |
| β = 102.682 (7)° |
| Oxford Diffraction Gemini S Ultra diffractometer | 2205 independent reflections |
| Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) | 1264 reflections with I > 2σ(I) |
| Tmin = 0.964, Tmax = 0.972 | Rint = 0.029 |
| 6419 measured reflections |
| R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
| wR(F2) = 0.060 | H-atom parameters constrained |
| S = 1.00 | Δρmax = 0.16 e Å−3 |
| 2205 reflections | Δρmin = −0.17 e Å−3 |
| 146 parameters |
Experimental. CrysAlisPro, Oxford Diffraction Ltd., Version 1.171.33.34d (release 27-02-2009 CrysAlis171 .NET) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
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 | ||
| O1 | 0.37126 (14) | −0.03674 (16) | 0.29797 (7) | 0.0612 (4) | |
| O2 | 0.15571 (11) | 0.62217 (15) | 0.36978 (6) | 0.0464 (3) | |
| C1 | 0.4953 (2) | −0.1274 (2) | 0.35211 (12) | 0.0720 (6) | |
| H1A | 0.5140 | −0.2396 | 0.3283 | 0.108* | |
| H1B | 0.4654 | −0.1471 | 0.4038 | 0.108* | |
| H1C | 0.5912 | −0.0572 | 0.3611 | 0.108* | |
| C2 | 0.32826 (18) | 0.1287 (2) | 0.32026 (10) | 0.0419 (4) | |
| C3 | 0.20616 (18) | 0.2107 (2) | 0.26345 (10) | 0.0471 (4) | |
| H3 | 0.1611 | 0.1537 | 0.2141 | 0.057* | |
| C4 | 0.15201 (17) | 0.3756 (2) | 0.27995 (10) | 0.0453 (4) | |
| H4 | 0.0692 | 0.4298 | 0.2424 | 0.054* | |
| C5 | 0.22169 (16) | 0.4607 (2) | 0.35303 (9) | 0.0381 (4) | |
| C6 | 0.34973 (16) | 0.3863 (2) | 0.40865 (9) | 0.0335 (4) | |
| C7 | 0.39884 (17) | 0.2148 (2) | 0.39259 (9) | 0.0374 (4) | |
| H7 | 0.4793 | 0.1586 | 0.4308 | 0.045* | |
| C8 | 0.42069 (14) | 0.49291 (19) | 0.48303 (9) | 0.0331 (4) | |
| C9 | 0.29155 (16) | 0.58847 (19) | 0.51278 (9) | 0.0340 (4) | |
| C10 | 0.16438 (17) | 0.6537 (2) | 0.45337 (10) | 0.0389 (4) | |
| C11 | 0.04103 (17) | 0.7507 (2) | 0.47368 (11) | 0.0484 (5) | |
| H11 | −0.0405 | 0.7970 | 0.4326 | 0.058* | |
| C12 | 0.04121 (19) | 0.7774 (2) | 0.55581 (11) | 0.0501 (5) | |
| H12 | −0.0398 | 0.8441 | 0.5704 | 0.060* | |
| C13 | 0.16141 (18) | 0.7056 (2) | 0.61689 (11) | 0.0466 (4) | |
| H13 | 0.1593 | 0.7207 | 0.6722 | 0.056* | |
| C14 | 0.28401 (16) | 0.6117 (2) | 0.59522 (10) | 0.0397 (4) | |
| H14 | 0.3635 | 0.5626 | 0.6365 | 0.048* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| O1 | 0.0783 (9) | 0.0499 (8) | 0.0496 (8) | 0.0048 (7) | 0.0012 (6) | −0.0137 (7) |
| O2 | 0.0441 (7) | 0.0518 (7) | 0.0374 (7) | 0.0114 (6) | −0.0043 (5) | 0.0007 (6) |
| C1 | 0.0937 (16) | 0.0533 (12) | 0.0666 (14) | 0.0160 (12) | 0.0122 (12) | −0.0051 (12) |
| C2 | 0.0445 (10) | 0.0415 (10) | 0.0395 (11) | −0.0044 (8) | 0.0088 (8) | −0.0064 (9) |
| C3 | 0.0441 (10) | 0.0614 (12) | 0.0319 (10) | −0.0077 (9) | −0.0003 (7) | −0.0105 (9) |
| C4 | 0.0365 (9) | 0.0615 (12) | 0.0336 (10) | 0.0011 (9) | −0.0019 (7) | −0.0005 (9) |
| C5 | 0.0331 (9) | 0.0438 (10) | 0.0356 (10) | −0.0003 (8) | 0.0032 (7) | −0.0019 (8) |
| C6 | 0.0263 (8) | 0.0423 (10) | 0.0295 (9) | −0.0025 (7) | 0.0010 (6) | −0.0003 (8) |
| C7 | 0.0344 (9) | 0.0429 (10) | 0.0320 (9) | −0.0009 (8) | 0.0012 (7) | −0.0002 (8) |
| C8 | 0.0326 (8) | 0.0341 (9) | 0.0299 (9) | 0.0004 (7) | 0.0007 (6) | 0.0020 (7) |
| C9 | 0.0300 (9) | 0.0343 (10) | 0.0362 (10) | −0.0012 (7) | 0.0039 (7) | 0.0003 (8) |
| C10 | 0.0361 (9) | 0.0398 (10) | 0.0384 (11) | −0.0001 (8) | 0.0027 (7) | −0.0014 (8) |
| C11 | 0.0351 (10) | 0.0475 (11) | 0.0581 (12) | 0.0091 (8) | 0.0003 (8) | 0.0009 (10) |
| C12 | 0.0409 (10) | 0.0473 (11) | 0.0640 (14) | 0.0060 (8) | 0.0159 (9) | −0.0050 (10) |
| C13 | 0.0451 (11) | 0.0496 (11) | 0.0473 (11) | 0.0002 (8) | 0.0149 (9) | −0.0012 (9) |
| C14 | 0.0342 (9) | 0.0430 (10) | 0.0404 (11) | −0.0020 (8) | 0.0047 (7) | 0.0020 (9) |
| O1—C2 | 1.3716 (18) | C6—C8 | 1.4865 (19) |
| O1—C1 | 1.4086 (19) | C7—H7 | 0.9300 |
| O2—C5 | 1.3930 (17) | C8—C8i | 1.357 (2) |
| O2—C10 | 1.3942 (17) | C8—C9 | 1.4918 (17) |
| C1—H1A | 0.9600 | C9—C10 | 1.3892 (19) |
| C1—H1B | 0.9600 | C9—C14 | 1.3960 (19) |
| C1—H1C | 0.9600 | C10—C11 | 1.3857 (19) |
| C2—C7 | 1.3816 (19) | C11—C12 | 1.379 (2) |
| C2—C3 | 1.390 (2) | C11—H11 | 0.9300 |
| C3—C4 | 1.373 (2) | C12—C13 | 1.387 (2) |
| C3—H3 | 0.9300 | C12—H12 | 0.9300 |
| C4—C5 | 1.3861 (19) | C13—C14 | 1.3777 (18) |
| C4—H4 | 0.9300 | C13—H13 | 0.9300 |
| C5—C6 | 1.3878 (18) | C14—H14 | 0.9300 |
| C6—C7 | 1.400 (2) | ||
| C2—O1—C1 | 118.46 (14) | C2—C7—H7 | 119.9 |
| C5—O2—C10 | 114.32 (12) | C6—C7—H7 | 119.9 |
| O1—C1—H1A | 109.5 | C8i—C8—C6 | 125.28 (16) |
| O1—C1—H1B | 109.5 | C8i—C8—C9 | 124.96 (17) |
| H1A—C1—H1B | 109.5 | C6—C8—C9 | 109.71 (11) |
| O1—C1—H1C | 109.5 | C10—C9—C14 | 117.04 (13) |
| H1A—C1—H1C | 109.5 | C10—C9—C8 | 117.27 (13) |
| H1B—C1—H1C | 109.5 | C14—C9—C8 | 125.63 (13) |
| O1—C2—C7 | 124.57 (15) | C11—C10—C9 | 122.30 (15) |
| O1—C2—C3 | 115.21 (15) | C11—C10—O2 | 117.08 (14) |
| C7—C2—C3 | 120.22 (15) | C9—C10—O2 | 120.62 (13) |
| C4—C3—C2 | 120.15 (15) | C12—C11—C10 | 118.85 (15) |
| C4—C3—H3 | 119.9 | C12—C11—H11 | 120.6 |
| C2—C3—H3 | 119.9 | C10—C11—H11 | 120.6 |
| C3—C4—C5 | 119.50 (15) | C11—C12—C13 | 120.42 (15) |
| C3—C4—H4 | 120.2 | C11—C12—H12 | 119.8 |
| C5—C4—H4 | 120.2 | C13—C12—H12 | 119.8 |
| C4—C5—C6 | 121.49 (15) | C14—C13—C12 | 119.68 (16) |
| C4—C5—O2 | 117.49 (14) | C14—C13—H13 | 120.2 |
| C6—C5—O2 | 121.00 (14) | C12—C13—H13 | 120.2 |
| C5—C6—C7 | 118.14 (14) | C13—C14—C9 | 121.50 (15) |
| C5—C6—C8 | 117.06 (13) | C13—C14—H14 | 119.3 |
| C7—C6—C8 | 124.75 (13) | C9—C14—H14 | 119.3 |
| C2—C7—C6 | 120.30 (15) | ||
| C1—O1—C2—C7 | 0.3 (2) | C5—C6—C8—C9 | 37.73 (17) |
| C1—O1—C2—C3 | 179.38 (14) | C7—C6—C8—C9 | −139.75 (14) |
| O1—C2—C3—C4 | 179.07 (13) | C8i—C8—C9—C10 | 140.63 (19) |
| C7—C2—C3—C4 | −1.8 (2) | C6—C8—C9—C10 | −36.97 (18) |
| C2—C3—C4—C5 | 1.0 (2) | C8i—C8—C9—C14 | −42.2 (3) |
| C3—C4—C5—C6 | 2.7 (2) | C6—C8—C9—C14 | 140.17 (15) |
| C3—C4—C5—O2 | −175.69 (13) | C14—C9—C10—C11 | 5.3 (2) |
| C10—O2—C5—C4 | 147.12 (13) | C8—C9—C10—C11 | −177.34 (14) |
| C10—O2—C5—C6 | −31.24 (19) | C14—C9—C10—O2 | −174.28 (13) |
| C4—C5—C6—C7 | −5.4 (2) | C8—C9—C10—O2 | 3.1 (2) |
| O2—C5—C6—C7 | 172.91 (12) | C5—O2—C10—C11 | −147.58 (13) |
| C4—C5—C6—C8 | 176.96 (12) | C5—O2—C10—C9 | 32.0 (2) |
| O2—C5—C6—C8 | −4.7 (2) | C9—C10—C11—C12 | −2.6 (2) |
| O1—C2—C7—C6 | 178.01 (13) | O2—C10—C11—C12 | 176.93 (15) |
| C3—C2—C7—C6 | −1.0 (2) | C10—C11—C12—C13 | −1.1 (2) |
| C5—C6—C7—C2 | 4.5 (2) | C11—C12—C13—C14 | 2.1 (2) |
| C8—C6—C7—C2 | −178.03 (13) | C12—C13—C14—C9 | 0.8 (2) |
| C5—C6—C8—C8i | −139.87 (19) | C10—C9—C14—C13 | −4.3 (2) |
| C7—C6—C8—C8i | 42.7 (3) | C8—C9—C14—C13 | 178.55 (14) |
| Symmetry code: (i) −x+1, −y+1, −z+1. |
Experimental details
| Crystal data | |
| Chemical formula | C28H20O4 |
| Mr | 420.28 |
| Crystal system, space group | Monoclinic, P21/c |
| Temperature (K) | 291 |
| a, b, c (Å) | 8.5699 (7), 7.5200 (6), 16.6101 (18) |
| β (°) | 102.682 (7) |
| V (Å3) | 1044.33 (16) |
| Z | 2 |
| Radiation type | Mo Kα |
| µ (mm−1) | 0.09 |
| Crystal size (mm) | 0.42 × 0.40 × 0.32 |
| Data collection | |
| Diffractometer | Oxford Diffraction Gemini S Ultra |
| Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) |
| Tmin, Tmax | 0.964, 0.972 |
| No. of measured, independent and observed [I > 2σ(I)] reflections | 6419, 2205, 1264 |
| Rint | 0.029 |
| (sin θ/λ)max (Å−1) | 0.633 |
| Refinement | |
| R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.060, 1.00 |
| No. of reflections | 2205 |
| No. of parameters | 146 |
| H-atom treatment | H-atom parameters constrained |
| Δρmax, Δρmin (e Å−3) | 0.16, −0.17 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012).
Acknowledgements
This work was supporting by the National Natural Science Foundation of China (grant Nos. 20972149 and 21272224).
References
Agranat, I. & Tapuhi, Y. (1979). J. Am. Chem. Soc. 101, 665–671. CrossRef CAS Web of Science Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Korenstein, R., Muszkat, K. A., Slifkin, M. A. & Fischer, E. (1976). J. Chem. Soc. Perkin Trans. 2, pp. 438–443. CrossRef Google Scholar
Mao, M., Wu, Q.-Q., Ren, M.-G. & Song, Q.-H. (2011). Org. Biomol Chem. 9, 3165–3169. Web of Science CrossRef CAS PubMed Google Scholar
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Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Shi, J., Chang, N., Li, C., Mei, J., Deng, C., Luo, X., Liu, Z., Bo, Z., Dong, Y. Q. & Tang, B. Z. (2012). Chem. Commun. 48, 10675–10677. Web of Science CSD CrossRef CAS Google Scholar
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The 2,2'-substituted bixanthenylidenes have two conformers (Z, E), which are unstable at room temperature (Korenstein et al., 1976). Z, E isomerization, with a low activation energy of 2,2'-disubstituted bixanthenylidenes, occurs easily at room temperature, and the ratio of Z/E in solution depends on the bulkiness of the the 2 and 2' substituents (Agranat & Tapuhi, 1979), 1:1.13 for the title compound. The crystal structure of the title compound shows that the E-type conformer lies on an inversion center located in the middle of the C8=C8i double bond (symmetry code: i = -x+1, -y+1, -z+1). The methoxy group is almost coplanar with the phenyl ring with a C1—O1—C2—C3 torsion angle of 179.38 (14) degrees (Fig.1). For related structures, see: Mills & Nyburg (1963); Shi et al. (2012).