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Acta Crystallogr Sect E Struct Rep Online. 2010 December 1; 66(Pt 12): o3239.
Published online 2010 November 20. doi:  10.1107/S1600536810047471
PMCID: PMC3011600

9α-Acet­oxy-1β,10α-ep­oxy­parthenolide

Abstract

The title compound, C17H22O6, was semi-synthesized from 9-hy­droxy­arthenolide, which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The mol­ecule contains fused five- and ten-membered rings: the five-membered lactone ring has a twisted conformation, whereas the ten-membered ring displays an approximate chair–chair conformation. The dihedral angle between the rings is 24.76 (9)°.

Related literature

For the isolation of 9-hy­droxy­arthenolide, see: El Hassany et al. (2004 [triangle]); Abdel Sattar et al. (1996 [triangle]). For the reactivity of this sesquiterpene, see: Castaneda-Acosta et al. (1993 [triangle]); Neukirch et al. (2003 [triangle]). For its biological activity, see: Abdel Sattar et al. (1996 [triangle]). For ring puckering parameters, see: Cremer & Pople (1975 [triangle]). For conformations of ten-membered rings, see: Castaneda-Acosta et al. (1997 [triangle]); Watson & Zabel (1982 [triangle]); Moumou et al. (2010 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o3239-scheme1.jpg

Experimental

Crystal data

  • C17H22O6
  • M r = 322.35
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o3239-efi1.jpg
  • a = 8.2390 (3) Å
  • b = 10.6482 (4) Å
  • c = 9.4633 (3) Å
  • β = 102.039 (2)°
  • V = 811.96 (5) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 298 K
  • 0.38 × 0.27 × 0.12 mm

Data collection

  • Bruker X8 APEX CCD area-detector diffractometer
  • 12911 measured reflections
  • 2718 independent reflections
  • 2480 reflections with I > 2σ(I)
  • R int = 0.023

Refinement

  • R[F 2 > 2σ(F 2)] = 0.038
  • wR(F 2) = 0.115
  • S = 1.05
  • 2718 reflections
  • 211 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 0.25 e Å−3
  • Δρmin = −0.17 e Å−3

Data collection: APEX2 (Bruker, 2007 [triangle]); cell refinement: SAINT (Bruker, 2007 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810047471/fj2367sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810047471/fj2367Isup2.hkl

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

Acknowledgments

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.

supplementary crystallographic information

Comment

The Natural sesquiterpene lactone (9α-hydroxyparthenolide) is the main constituent of the chloroform extract of aerial parts of Anvillea radiata (El Hassany et al., 2004), and of Anvillea garcini(Abdel Sattar et al.,1996). The reactivity of this sesuiterpène and its derivatives has been the subject of several studies (Castaneda-Acosta et al.,1993; Neukirch et al., 2003), in order to prepare products with high value added, used in industrial pharmacology. In the same context, we carried out the acetylation followed by epoxydation of 9α-hydroxyparthenolide. Thus, the action of one equivalent of acetic anhydride on this sesquiterpene in pyridine at 0°C leads to quantitative yield 9α-acétoxyparthenolide. The treatment of this latter with one equivalent of meta-choroperbenzoïque acid (mCPBA) in dichloromethane at room temperature gives 9α-acetoxy-1β, 10β-epoxyparthenolide with a yield of 95%. The structure of this new product was determined by NMR spectral analysis of 1H, 13 C and mass spectrometry, and confirmed by a study of X ray crystallography. The structure of (I) was established by 1H and 13 C NMR and confirmed by its single-crystal X-ray structure.The molecule is built up from two fused five-and ten-membered rings.(Fig. 1). The five-membered ring adopts a twisted conformation,as indicated by Cremer & Pople (1975) puckering parameters Q = 0.26 (2) Å and [var phi] = 23.77 (4)°. The ten-membered ring displays an approximate chair-chair conformation. This is the typical conformation observed for other sesquiterpenes lactones (Moumou et al., 2010; Watson & Zabel, 1982; Castaneda-Acosta et al., 1997).

Experimental

To a solution of 1,2 g (4,54 mmol) of 9α-hydroxyparthenolide in 30 ml of pyridine was added 10 ml of acetic anhydride. The mixture is left stirring for 12 h at room temperature and then treated with 100 ml of ice water and extracted with chloroform. The residue obtained after drying and evaporation of solvent was chromatographed on silica gel eluting with hexane-ethyl acetate (80/20) and allowed to isolate in pure form with a yield qantitatif the 9α-acétoxyparthenolide. To 0.5 g (1,6 mmol) of this latter dissolved in 40 ml of dichloromethane is added an equivalent of acid meta chloroperbenzoïque (mCPBA). The reaction mixture was stirred at room temperature for 3 h, then treated with a solution of sodium bisulfite at 10% and extracted with dichloromethane. The organic phase is dried over sodium sulfate and then evaporated under vacuum. chromatography of the residue obtained on silica gel column eluting with hexane ethyl acetate (75/25), allowed us to obtain the 9α-Acetoxy-1β, 10α-epoxyparthenolide with a yield of 80%.Crystallization of this product was carried out at room temperature from an ethyl acetate solution.

Refinement

All H atoms were fixed geometrically and treated as riding with C—H = 0.96 Å (methyl),0.97 Å (methylene), 0.98Å (methine) with Uiso(H) = 1.2Ueq(methylene, methine and OH) or Uiso(H) = 1.5Ueq(methyl). In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined and thus 2417 Friedel pairs were merged and any references to the Flack parameter were removed.

Figures

Fig. 1.
Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii.

Crystal data

C17H22O6F(000) = 344
Mr = 322.35Dx = 1.318 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 12911 reflections
a = 8.2390 (3) Åθ = 2.2–31.0°
b = 10.6482 (4) ŵ = 0.10 mm1
c = 9.4633 (3) ÅT = 298 K
β = 102.039 (2)°PRISM, colourless
V = 811.96 (5) Å30.38 × 0.27 × 0.12 mm
Z = 2

Data collection

Bruker X8 APEX CCD area-detector diffractometer2480 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.023
graphiteθmax = 31.1°, θmin = 2.2°
[var phi] and ω scansh = −11→11
12911 measured reflectionsk = −15→15
2718 independent reflectionsl = −13→13

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.115H-atom parameters constrained
S = 1.05w = 1/[σ2(Fo2) + (0.0742P)2 + 0.0491P] where P = (Fo2 + 2Fc2)/3
2718 reflections(Δ/σ)max < 0.001
211 parametersΔρmax = 0.25 e Å3
1 restraintΔρmin = −0.17 e Å3

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
C140.6599 (2)−0.1768 (2)1.05001 (19)0.0485 (4)
H14A0.5629−0.22651.05090.073*
H14B0.7023−0.14401.14500.073*
H14C0.7431−0.22821.02100.073*
C150.6072 (3)−0.3610 (2)0.7190 (3)0.0648 (5)
H15A0.7103−0.37760.69060.097*
H15B0.5426−0.43670.71130.097*
H15C0.6289−0.33190.81720.097*
C10.46449 (18)−0.06799 (17)0.82978 (17)0.0403 (3)
H10.4716−0.01450.74700.048*
C20.3450 (2)−0.1765 (2)0.7955 (2)0.0521 (4)
H2A0.2344−0.14810.80050.063*
H2B0.3768−0.24170.86750.063*
C30.3418 (3)−0.2314 (3)0.6452 (3)0.0644 (6)
H3A0.2744−0.30680.63270.077*
H3B0.2905−0.17120.57240.077*
C40.5134 (3)−0.2628 (2)0.6226 (2)0.0537 (4)
C50.5937 (2)−0.1649 (2)0.55053 (18)0.0501 (4)
H50.5264−0.08920.52530.060*
C60.7768 (2)−0.14210 (17)0.57840 (17)0.0447 (4)
H60.8377−0.21710.61950.054*
C70.82874 (19)−0.02749 (15)0.67649 (15)0.0366 (3)
H70.73570.03180.66010.044*
C80.87578 (18)−0.05478 (18)0.83958 (15)0.0393 (3)
H8A0.8723−0.14490.85350.047*
H8B0.9894−0.02790.87510.047*
C90.76603 (17)0.00787 (16)0.93218 (15)0.0352 (3)
H90.83330.02041.02950.042*
C100.61532 (17)−0.06993 (15)0.94522 (15)0.0356 (3)
C110.9645 (2)0.02787 (18)0.61024 (19)0.0464 (4)
C120.9353 (3)−0.0178 (2)0.4586 (2)0.0559 (5)
C131.0911 (3)0.1006 (3)0.6654 (3)0.0665 (6)
H13A1.16560.12500.60910.080*
H13B1.10600.12760.76070.080*
C160.8244 (2)0.22159 (18)0.9006 (2)0.0460 (4)
C170.7628 (3)0.3407 (2)0.8271 (2)0.0597 (5)
H17A0.74510.40110.89760.090*
H17B0.66000.32540.76000.090*
H17C0.84320.37260.77600.090*
O10.5260 (3)−0.2753 (2)0.47208 (17)0.0731 (5)
O20.47027 (14)−0.00130 (14)0.96360 (14)0.0473 (3)
O30.8194 (2)−0.10899 (18)0.44012 (14)0.0622 (4)
O40.9965 (3)0.0176 (3)0.36135 (19)0.0840 (6)
O50.71087 (14)0.12924 (11)0.87370 (13)0.0387 (2)
O60.96035 (19)0.20593 (19)0.9760 (2)0.0711 (5)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C140.0535 (9)0.0498 (10)0.0430 (8)0.0018 (8)0.0119 (7)0.0129 (7)
C150.0920 (16)0.0371 (9)0.0689 (13)0.0029 (10)0.0251 (12)0.0000 (9)
C10.0353 (6)0.0393 (7)0.0477 (7)0.0015 (6)0.0119 (5)0.0030 (6)
C20.0378 (7)0.0526 (10)0.0660 (11)−0.0065 (7)0.0109 (7)0.0037 (9)
C30.0513 (10)0.0673 (14)0.0683 (12)−0.0167 (10)−0.0022 (9)−0.0061 (11)
C40.0654 (11)0.0462 (10)0.0474 (9)−0.0088 (8)0.0072 (8)−0.0093 (7)
C50.0593 (9)0.0500 (10)0.0377 (7)−0.0004 (8)0.0028 (7)0.0003 (7)
C60.0588 (9)0.0410 (8)0.0367 (7)0.0087 (7)0.0156 (6)0.0014 (6)
C70.0414 (6)0.0376 (7)0.0331 (6)0.0092 (5)0.0134 (5)0.0039 (5)
C80.0379 (6)0.0472 (8)0.0340 (6)0.0098 (6)0.0105 (5)0.0069 (6)
C90.0367 (6)0.0383 (7)0.0307 (5)−0.0009 (5)0.0077 (4)−0.0002 (5)
C100.0374 (6)0.0353 (7)0.0366 (6)0.0030 (5)0.0135 (5)0.0008 (5)
C110.0546 (8)0.0436 (8)0.0470 (8)0.0113 (7)0.0244 (7)0.0111 (7)
C120.0688 (11)0.0586 (12)0.0482 (9)0.0182 (10)0.0303 (8)0.0098 (8)
C130.0757 (14)0.0592 (13)0.0730 (13)−0.0089 (11)0.0347 (11)0.0052 (11)
C160.0531 (9)0.0411 (8)0.0491 (8)−0.0111 (7)0.0231 (7)−0.0132 (7)
C170.0799 (13)0.0397 (9)0.0674 (12)−0.0121 (10)0.0336 (10)−0.0033 (9)
O10.0935 (12)0.0769 (12)0.0452 (8)−0.0166 (11)0.0059 (7)−0.0190 (8)
O20.0473 (6)0.0429 (6)0.0586 (7)0.0051 (5)0.0267 (5)−0.0034 (6)
O30.0873 (10)0.0679 (10)0.0372 (6)0.0057 (9)0.0268 (6)−0.0042 (6)
O40.1043 (14)0.1021 (15)0.0613 (9)0.0130 (13)0.0531 (10)0.0150 (11)
O50.0410 (5)0.0329 (5)0.0432 (5)−0.0035 (4)0.0110 (4)−0.0027 (4)
O60.0544 (8)0.0626 (10)0.0909 (13)−0.0184 (8)0.0025 (8)−0.0182 (9)

Geometric parameters (Å, °)

C14—C101.504 (2)C6—C71.539 (2)
C14—H14A0.9600C6—H60.9800
C14—H14B0.9600C7—C111.511 (2)
C14—H14C0.9600C7—C81.5386 (19)
C15—C41.493 (3)C7—H70.9800
C15—H15A0.9600C8—C91.537 (2)
C15—H15B0.9600C8—H8A0.9700
C15—H15C0.9600C8—H8B0.9700
C1—O21.444 (2)C9—O51.442 (2)
C1—C101.474 (2)C9—C101.519 (2)
C1—C21.508 (3)C9—H90.9800
C1—H10.9800C10—O21.4419 (18)
C2—C31.534 (3)C11—C131.316 (3)
C2—H2A0.9700C11—C121.486 (3)
C2—H2B0.9700C12—O41.199 (2)
C3—C41.511 (3)C12—O31.348 (3)
C3—H3A0.9700C13—H13A0.9300
C3—H3B0.9700C13—H13B0.9300
C4—O11.456 (3)C16—O61.207 (3)
C4—C51.476 (3)C16—O51.345 (2)
C5—O11.439 (3)C16—C171.484 (3)
C5—C61.496 (3)C17—H17A0.9600
C5—H50.9800C17—H17B0.9600
C6—O31.467 (2)C17—H17C0.9600
C10—C14—H14A109.5C7—C6—H6110.6
C10—C14—H14B109.5C11—C7—C8115.88 (14)
H14A—C14—H14B109.5C11—C7—C6101.30 (13)
C10—C14—H14C109.5C8—C7—C6115.81 (14)
H14A—C14—H14C109.5C11—C7—H7107.8
H14B—C14—H14C109.5C8—C7—H7107.8
C4—C15—H15A109.5C6—C7—H7107.8
C4—C15—H15B109.5C9—C8—C7115.78 (12)
H15A—C15—H15B109.5C9—C8—H8A108.3
C4—C15—H15C109.5C7—C8—H8A108.3
H15A—C15—H15C109.5C9—C8—H8B108.3
H15B—C15—H15C109.5C7—C8—H8B108.3
O2—C1—C1059.23 (10)H8A—C8—H8B107.4
O2—C1—C2117.75 (14)O5—C9—C10108.82 (11)
C10—C1—C2124.07 (16)O5—C9—C8110.26 (12)
O2—C1—H1114.7C10—C9—C8113.44 (13)
C10—C1—H1114.7O5—C9—H9108.1
C2—C1—H1114.7C10—C9—H9108.1
C1—C2—C3112.05 (17)C8—C9—H9108.1
C1—C2—H2A109.2O2—C10—C159.36 (10)
C3—C2—H2A109.2O2—C10—C14113.50 (13)
C1—C2—H2B109.2C1—C10—C14123.48 (15)
C3—C2—H2B109.2O2—C10—C9116.46 (13)
H2A—C2—H2B107.9C1—C10—C9120.62 (13)
C4—C3—C2112.34 (16)C14—C10—C9112.01 (13)
C4—C3—H3A109.1C13—C11—C12122.04 (18)
C2—C3—H3A109.1C13—C11—C7131.20 (19)
C4—C3—H3B109.1C12—C11—C7106.75 (17)
C2—C3—H3B109.1O4—C12—O3121.8 (2)
H3A—C3—H3B107.9O4—C12—C11129.0 (3)
O1—C4—C558.81 (14)O3—C12—C11109.18 (15)
O1—C4—C15113.58 (19)C11—C13—H13A120.0
C5—C4—C15123.53 (19)C11—C13—H13B120.0
O1—C4—C3114.76 (18)H13A—C13—H13B120.0
C5—C4—C3115.6 (2)O6—C16—O5122.27 (19)
C15—C4—C3116.7 (2)O6—C16—C17125.43 (18)
O1—C5—C459.90 (14)O5—C16—C17112.30 (16)
O1—C5—C6119.44 (19)C16—C17—H17A109.5
C4—C5—C6124.49 (17)C16—C17—H17B109.5
O1—C5—H5114.1H17A—C17—H17B109.5
C4—C5—H5114.1C16—C17—H17C109.5
C6—C5—H5114.1H17A—C17—H17C109.5
O3—C6—C5107.57 (14)H17B—C17—H17C109.5
O3—C6—C7105.02 (14)C5—O1—C461.28 (13)
C5—C6—C7112.25 (14)C10—O2—C161.41 (10)
O3—C6—H6110.6C12—O3—C6110.63 (14)
C5—C6—H6110.6C16—O5—C9115.58 (13)

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2367).

References

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