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Acta Crystallogr Sect E Struct Rep Online. 2009 March 1; 65(Pt 3): o586.
Published online 2009 February 25. doi:  10.1107/S1600536809004231
PMCID: PMC2968613

2-(4-Methoxyphenoxy)-6-methyl-3-oxo-3,6-dihydro-2H-pyran-4-yl benzoate

Abstract

The title compound, C20H18O6, has been synthesized from 4-methoxy­phenyl 3-O-benzo­yloxy-α-l-rhamnopyran­oside by oxidation on treatment with pyridinium dichromate in the presence of acetic anhydride. In the mol­ecule, the pyran ring adopts an envelope conformation with the O atom at the flap position. Weak inter­molecular C—H(...)O hydrogen bonding is present in the crystal structure.

Related literature

For general background to enolone derivatives, see: Schmidt et al. (1954 [triangle]); Hodges et al. (1963 [triangle]); Bevan et al. (1963 [triangle]); Ripperger & Seifert (1975 [triangle]); Yan et al. (2008 [triangle]).

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Object name is e-65-0o586-scheme1.jpg

Experimental

Crystal data

  • C20H18O6
  • M r = 354.34
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-0o586-efi1.jpg
  • a = 8.5906 (17) Å
  • b = 11.594 (2) Å
  • c = 17.404 (4) Å
  • V = 1733.4 (6) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 173 (2) K
  • 0.80 × 0.72 × 0.40 mm

Data collection

  • Rigaku R-Axis Rapid IP are-detector diffractometer
  • Absorption correction: multi-scan (ABSCOR; Higashi, 1995 [triangle]) T min = 0.924, T max = 0.961
  • 3953 measured reflections
  • 2262 independent reflections
  • 1752 reflections with I > 2σ(I)
  • R int = 0.015

Refinement

  • R[F 2 > 2σ(F 2)] = 0.034
  • wR(F 2) = 0.055
  • S = 0.87
  • 2262 reflections
  • 236 parameters
  • H-atom parameters constrained
  • Δρmax = 0.17 e Å−3
  • Δρmin = −0.24 e Å−3

Data collection: RAPID-AUTO (Rigaku, 2001 [triangle]); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809004231/xu2467sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809004231/xu2467Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors thank the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry (No. 21168020) and the Doctoral Program Foundation of Institutions of Higher Education of China (No. 20070019072) for support.

supplementary crystallographic information

Comment

The enolone structural unit is often present in nature products, such as brevifolic acid, a constituent of the ellagitannins (Schmidt et al., 1954), meliacinslike cedrelone and anthothecol (Hodges et al., 1963; Bevan et al., 1963) or triterpenoids of the elaterin type, which are widely distributed in cucurbitaceous and cruciferous plants (Ripperger & Seifert, 1975). In a continuation of our search for alcohol oxidation (Yan et al., 2008), herein we present the crystal structure of the title compound, which was produced by oxidation with PDC and acetic anhydride.

In the molecule of the title compound (Fig. 1), the pyran ring conformation can be described as an envelope, with C1/C2/C3/C4/C5 lying almost on the same plane and O1 deviating from this mean plane. The terminal benzene rings of the molecule are nearly perpendicular to each other with a dihedral angle of 83.6 (1)°. The weak intermolecular C—H···O hydrogen bonding presents in the crystal structure (Table 1).

Experimental

A mixture of 4-methoxyphenyl 3-O-benzoyloxy-a-L-rhamnopyranoside (3.74 g, 10 mmol), pyridinium dichromate (4.60 g, 12 mmol), and acetic anhydride (5.68 ml, 60 mmol) in CH2Cl2 (40 ml) was stirred at reflux for 8 h, at the end of which time TLC (4:1 petroleumether–EtOAc) indicated that the reaction was complete. After direct concentration of the reaction mixture, the dark brown residue was diluted with EtOAc (60 ml) and the solution was passed through a short (5–10 cm) silica-gel column. The column was eluted with EtOAc and the eluents were concentrated and coevaporated with toluene. The residue was subjected to silica-gel column chromatography again (4:1 petroleum ether–EtOAc) to give the title compound (2.48 g, 70%). Single crystals suitable for X-ray measurements were obtained by recrystallization from 8:1 petroleumether–EtOAc at room temperature.

Refinement

H atoms were positioned geometrically, with C—H = 0.95 Å, 0.98 Å and 1.00 Å for aromatic, methyl and methine H, respectively, and constrained to ride on their parent atoms, with Uiso(H) = xUeq(C), where x= 1.5 for methyl H and x = 1.2 for other H. The absolute structure was not determined for this structure, Friedel pairs were merged.

Figures

Fig. 1.
The molecular structure of the title compound, showing the atomic labelling and displacement ellipsoids drawn at the 50% probability level.

Crystal data

C20H18O6F(000) = 744
Mr = 354.34Dx = 1.358 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 789 reflections
a = 8.5906 (17) Åθ = 2.2–27.5°
b = 11.594 (2) ŵ = 0.10 mm1
c = 17.404 (4) ÅT = 173 K
V = 1733.4 (6) Å3Block, colorless
Z = 40.80 × 0.72 × 0.40 mm

Data collection

Rigaku R-Axis Rapid IP are-detector diffractometer2262 independent reflections
Radiation source: rotating anode1752 reflections with I > 2σ(I)
graphiteRint = 0.015
ω scanθmax = 27.4°, θmin = 2.1°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)h = −11→11
Tmin = 0.924, Tmax = 0.961k = −14→15
3953 measured reflectionsl = −22→22

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.034H-atom parameters constrained
wR(F2) = 0.055w = 1/[σ2(Fo2)]
S = 0.87(Δ/σ)max = 0.001
2262 reflectionsΔρmax = 0.17 e Å3
236 parametersΔρmin = −0.24 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0215 (13)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
O11.17184 (15)0.59200 (11)0.94630 (8)0.0262 (4)
O20.93224 (17)0.89681 (11)0.91264 (8)0.0298 (4)
O31.04268 (19)0.94639 (12)1.02536 (9)0.0370 (4)
O41.21198 (18)0.84659 (12)0.84053 (9)0.0372 (4)
O51.13746 (15)0.59345 (11)0.81269 (7)0.0230 (3)
O61.36640 (18)0.16881 (11)0.72242 (9)0.0371 (4)
C11.0087 (2)0.58644 (17)0.96426 (13)0.0278 (5)
H1A0.95750.53020.92880.033*
C20.9327 (3)0.70107 (17)0.95530 (12)0.0290 (5)
H2A0.83180.71230.97630.035*
C31.0009 (3)0.78794 (17)0.91900 (12)0.0257 (5)
C41.1459 (2)0.77091 (16)0.87611 (12)0.0250 (5)
C51.2071 (2)0.64760 (16)0.87719 (11)0.0236 (5)
H5A1.32260.64880.87010.028*
C60.9976 (3)0.5411 (2)1.04592 (14)0.0425 (6)
H6A1.04860.46571.04910.064*
H6B0.88780.53331.06040.064*
H6C1.04910.59521.08100.064*
C70.9639 (2)0.97192 (17)0.97094 (13)0.0251 (5)
C80.8888 (2)1.08488 (16)0.95760 (12)0.0230 (5)
C90.8571 (3)1.15548 (17)1.02010 (13)0.0304 (5)
H9A0.88521.13161.07050.037*
C100.7844 (3)1.26088 (18)1.00880 (15)0.0379 (6)
H10A0.76211.30921.05150.045*
C110.7445 (3)1.29565 (18)0.93534 (14)0.0384 (6)
H11A0.69461.36790.92770.046*
C120.7767 (3)1.22605 (17)0.87332 (14)0.0340 (6)
H12A0.74981.25070.82300.041*
C130.8478 (2)1.12062 (16)0.88406 (12)0.0278 (5)
H13A0.86871.07240.84120.033*
C141.1981 (2)0.48407 (16)0.79498 (10)0.0203 (5)
C151.3486 (2)0.47295 (16)0.76804 (11)0.0242 (5)
H15A1.41470.53850.76520.029*
C161.4024 (2)0.36583 (16)0.74524 (12)0.0260 (5)
H16A1.50600.35730.72710.031*
C171.3043 (2)0.27089 (16)0.74899 (12)0.0247 (5)
C181.1540 (3)0.28231 (17)0.77601 (12)0.0278 (5)
H18A1.08690.21730.77840.033*
C191.1018 (2)0.39045 (16)0.79972 (11)0.0260 (5)
H19A0.99920.39910.81920.031*
C201.2665 (3)0.07108 (16)0.72123 (15)0.0446 (7)
H20A1.32330.00440.70100.067*
H20B1.17650.08710.68830.067*
H20C1.23070.05440.77350.067*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0262 (8)0.0268 (8)0.0256 (8)0.0052 (7)−0.0006 (6)0.0013 (7)
O20.0395 (9)0.0208 (8)0.0292 (8)0.0097 (7)−0.0036 (7)−0.0066 (7)
O30.0455 (10)0.0285 (9)0.0370 (10)0.0032 (7)−0.0157 (8)−0.0016 (7)
O40.0356 (10)0.0274 (8)0.0486 (10)−0.0030 (8)0.0019 (8)0.0054 (8)
O50.0236 (8)0.0212 (7)0.0244 (7)0.0041 (7)−0.0024 (6)−0.0035 (6)
O60.0275 (9)0.0231 (8)0.0607 (11)0.0022 (7)−0.0003 (9)−0.0118 (8)
C10.0272 (12)0.0244 (12)0.0319 (12)0.0035 (10)0.0030 (10)0.0004 (10)
C20.0276 (12)0.0339 (13)0.0255 (12)0.0059 (10)0.0044 (10)−0.0026 (10)
C30.0294 (13)0.0236 (11)0.0242 (11)0.0062 (10)−0.0048 (10)−0.0063 (10)
C40.0274 (13)0.0233 (11)0.0244 (11)−0.0013 (10)−0.0071 (10)−0.0039 (10)
C50.0199 (11)0.0251 (11)0.0258 (11)0.0026 (9)−0.0010 (10)−0.0013 (10)
C60.0481 (15)0.0426 (14)0.0367 (14)0.0099 (13)0.0097 (12)0.0110 (12)
C70.0249 (12)0.0227 (11)0.0278 (12)−0.0028 (10)0.0029 (10)−0.0022 (10)
C80.0196 (11)0.0199 (11)0.0295 (12)−0.0031 (9)0.0026 (9)−0.0009 (9)
C90.0358 (14)0.0268 (12)0.0287 (12)−0.0022 (11)0.0055 (11)−0.0010 (10)
C100.0484 (16)0.0218 (11)0.0434 (15)0.0026 (12)0.0142 (13)−0.0060 (11)
C110.0384 (15)0.0229 (12)0.0540 (17)0.0059 (11)0.0116 (13)0.0059 (11)
C120.0355 (14)0.0283 (13)0.0382 (14)0.0017 (11)0.0016 (12)0.0096 (11)
C130.0284 (12)0.0262 (12)0.0288 (12)−0.0008 (10)0.0030 (10)−0.0023 (10)
C140.0229 (12)0.0194 (10)0.0185 (10)0.0038 (9)−0.0009 (9)−0.0022 (8)
C150.0235 (12)0.0207 (10)0.0284 (12)−0.0047 (10)0.0006 (10)0.0005 (9)
C160.0170 (11)0.0284 (12)0.0326 (12)0.0022 (9)0.0041 (10)−0.0016 (10)
C170.0243 (13)0.0214 (11)0.0285 (12)0.0056 (9)−0.0048 (10)−0.0028 (9)
C180.0236 (12)0.0232 (11)0.0367 (13)−0.0053 (10)0.0011 (11)−0.0004 (10)
C190.0212 (12)0.0280 (12)0.0287 (12)0.0001 (10)0.0040 (9)−0.0019 (10)
C200.0363 (15)0.0194 (11)0.0782 (19)0.0025 (11)−0.0133 (14)−0.0114 (12)

Geometric parameters (Å, °)

O1—C51.398 (2)C8—C131.391 (3)
O1—C11.437 (2)C9—C101.386 (3)
O2—C71.365 (2)C9—H9A0.9500
O2—C31.398 (2)C10—C111.384 (3)
O3—C71.201 (2)C10—H10A0.9500
O4—C41.215 (2)C11—C121.376 (3)
O5—C141.405 (2)C11—H11A0.9500
O5—C51.418 (2)C12—C131.379 (3)
O6—C171.378 (2)C12—H12A0.9500
O6—C201.422 (2)C13—H13A0.9500
C1—C21.489 (3)C14—C191.367 (3)
C1—C61.518 (3)C14—C151.381 (3)
C1—H1A1.0000C15—C161.383 (3)
C2—C31.326 (3)C15—H15A0.9500
C2—H2A0.9500C16—C171.387 (3)
C3—C41.465 (3)C16—H16A0.9500
C4—C51.523 (3)C17—C181.381 (3)
C5—H5A1.0000C18—C191.394 (3)
C6—H6A0.9800C18—H18A0.9500
C6—H6B0.9800C19—H19A0.9500
C6—H6C0.9800C20—H20A0.9800
C7—C81.478 (3)C20—H20B0.9800
C8—C91.388 (3)C20—H20C0.9800
C5—O1—C1114.77 (15)C10—C9—H9A120.1
C7—O2—C3115.67 (16)C8—C9—H9A120.1
C14—O5—C5114.64 (14)C11—C10—C9120.0 (2)
C17—O6—C20117.11 (17)C11—C10—H10A120.0
O1—C1—C2111.40 (17)C9—C10—H10A120.0
O1—C1—C6106.29 (18)C12—C11—C10120.3 (2)
C2—C1—C6112.29 (19)C12—C11—H11A119.9
O1—C1—H1A108.9C10—C11—H11A119.9
C2—C1—H1A108.9C11—C12—C13120.2 (2)
C6—C1—H1A108.9C11—C12—H12A119.9
C3—C2—C1122.3 (2)C13—C12—H12A119.9
C3—C2—H2A118.9C12—C13—C8120.1 (2)
C1—C2—H2A118.9C12—C13—H13A120.0
C2—C3—O2122.5 (2)C8—C13—H13A120.0
C2—C3—C4121.08 (19)C19—C14—C15120.83 (18)
O2—C3—C4116.11 (18)C19—C14—O5118.64 (18)
O4—C4—C3124.03 (19)C15—C14—O5120.37 (17)
O4—C4—C5121.5 (2)C14—C15—C16119.60 (18)
C3—C4—C5114.42 (18)C14—C15—H15A120.2
O1—C5—O5112.68 (15)C16—C15—H15A120.2
O1—C5—C4111.63 (17)C15—C16—C17119.73 (19)
O5—C5—C4105.08 (15)C15—C16—H16A120.1
O1—C5—H5A109.1C17—C16—H16A120.1
O5—C5—H5A109.1O6—C17—C18123.95 (19)
C4—C5—H5A109.1O6—C17—C16115.51 (19)
C1—C6—H6A109.5C18—C17—C16120.52 (18)
C1—C6—H6B109.5C17—C18—C19119.18 (19)
H6A—C6—H6B109.5C17—C18—H18A120.4
C1—C6—H6C109.5C19—C18—H18A120.4
H6A—C6—H6C109.5C14—C19—C18120.1 (2)
H6B—C6—H6C109.5C14—C19—H19A119.9
O3—C7—O2122.79 (19)C18—C19—H19A119.9
O3—C7—C8126.03 (19)O6—C20—H20A109.5
O2—C7—C8111.18 (18)O6—C20—H20B109.5
C9—C8—C13119.72 (19)H20A—C20—H20B109.5
C9—C8—C7119.00 (19)O6—C20—H20C109.5
C13—C8—C7121.27 (18)H20A—C20—H20C109.5
C10—C9—C8119.8 (2)H20B—C20—H20C109.5
C5—O1—C1—C2−48.6 (2)O3—C7—C8—C13157.1 (2)
C5—O1—C1—C6−171.17 (16)O2—C7—C8—C13−23.2 (3)
O1—C1—C2—C314.0 (3)C13—C8—C9—C100.2 (3)
C6—C1—C2—C3133.1 (2)C7—C8—C9—C10−179.0 (2)
C1—C2—C3—O2−177.84 (19)C8—C9—C10—C11−0.3 (3)
C1—C2—C3—C48.9 (3)C9—C10—C11—C120.0 (4)
C7—O2—C3—C289.0 (2)C10—C11—C12—C130.6 (4)
C7—O2—C3—C4−97.4 (2)C11—C12—C13—C8−0.7 (3)
C2—C3—C4—O4178.5 (2)C9—C8—C13—C120.3 (3)
O2—C3—C4—O44.8 (3)C7—C8—C13—C12179.49 (19)
C2—C3—C4—C50.3 (3)C5—O5—C14—C19116.7 (2)
O2—C3—C4—C5−173.41 (17)C5—O5—C14—C15−67.9 (2)
C1—O1—C5—O5−59.9 (2)C19—C14—C15—C160.3 (3)
C1—O1—C5—C458.1 (2)O5—C14—C15—C16−174.99 (17)
C14—O5—C5—O1−68.5 (2)C14—C15—C16—C170.6 (3)
C14—O5—C5—C4169.78 (16)C20—O6—C17—C181.8 (3)
O4—C4—C5—O1149.13 (18)C20—O6—C17—C16−176.5 (2)
C3—C4—C5—O1−32.6 (2)C15—C16—C17—O6177.71 (17)
O4—C4—C5—O5−88.4 (2)C15—C16—C17—C18−0.6 (3)
C3—C4—C5—O589.8 (2)O6—C17—C18—C19−178.37 (19)
C3—O2—C7—O3−1.6 (3)C16—C17—C18—C19−0.2 (3)
C3—O2—C7—C8178.67 (17)C15—C14—C19—C18−1.1 (3)
O3—C7—C8—C9−23.8 (3)O5—C14—C19—C18174.26 (17)
O2—C7—C8—C9155.93 (18)C17—C18—C19—C141.0 (3)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C15—H15A···O6i0.952.423.343 (2)163

Symmetry codes: (i) −x+3, y+1/2, −z+3/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: XU2467).

References

  • Bevan, C. W. L., Rees, A. H. & Taylor, D. A. H. (1963). J. Chem. Soc. pp. 983–989.
  • Higashi, T. (1995). ABSCOR Rigaku Corporation, Tokyo, Japan.
  • Hodges, R., McGeachin, S. G. & Raphael, R. A. H. (1963). J. Chem. Soc. pp. 2515–2526.
  • Rigaku (2001). RAPID-AUTO Rigaku Corporation, Tokyo.
  • Ripperger, H. & Seifert, K. (1975). Tetrahedron, 31, 1561–1563.
  • Schmidt, O. T. & Bernauer, K. (1954). Justus Liebigs Ann. Chem 588, 211–230.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Yan, S. Q., Liang, X. M., Diao, P. Y., Yang, Y., Zhang, J. J., Wang, D. Q. & Kong, F. Z. (2008). Carbohydr. Res.343, 3107–3111. [PubMed]

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