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Acta Crystallogr Sect E Struct Rep Online. 2010 March 1; 66(Pt 3): o607.
Published online 2010 February 13. doi:  10.1107/S1600536810005167
PMCID: PMC2983525

4′-Bromo­butyl ent-16-oxobeyeran-19-oate

Abstract

The title compound, C24H37BrO3, is a tetra­cyclic diterpenoid with a beyerane skeleton, synthesized by esterification of isosteviol. It comprises a fused four-ring system A/B/C/D. Rings A and B have a chair conformation, whereas ring C is an unsymmetrical distorted chair; the remaining five-membered ring D adopts an envelope conformation. The stereochemistry of the A/B and B/C ring junctions are trans, while the C/D junction is cis.

Related literature

For the pharmacological activity of isosteviol, see: Liu et al. (2001 [triangle]); Mizushina et al. (2005 [triangle]); Wong et al. (2004 [triangle]); Xu et al. (2007 [triangle]). For ring conformations, see: Cremer & Pople (1975 [triangle]). For the synthesis of isosteviol derivates via esterification and bromination, see: Cai et al. (2009 [triangle]); Chen (2010 [triangle]).

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Object name is e-66-0o607-scheme1.jpg

Experimental

Crystal data

  • C24H37BrO3
  • M r = 453.45
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-0o607-efi1.jpg
  • a = 7.4335 (10) Å
  • b = 9.7732 (14) Å
  • c = 30.920 (4) Å
  • V = 2246.3 (5) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 1.85 mm−1
  • T = 298 K
  • 0.45 × 0.43 × 0.37 mm

Data collection

  • Bruker SMART CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 1999 [triangle]) T min = 0.490, T max = 0.548
  • 11802 measured reflections
  • 3955 independent reflections
  • 3041 reflections with I > 2/s(I)
  • R int = 0.052

Refinement

  • R[F 2 > 2σ(F 2)] = 0.042
  • wR(F 2) = 0.108
  • S = 1.00
  • 3955 reflections
  • 256 parameters
  • H-atom parameters constrained
  • Δρmax = 0.64 e Å−3
  • Δρmin = −0.25 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1657 Friedel pairs
  • Flack parameter: 0.065 (11)

Data collection: SMART (Bruker, 1999 [triangle]); cell refinement: SAINT (Bruker, 1999 [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: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 [triangle]).

Supplementary Material

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S1600536810005167/bg2330sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810005167/bg2330Isup2.hkl

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

Acknowledgments

We are grateful to the China Ministry of Health Foundation for Scientific Research (project no. WKJ2005-2-022) for financial support.

supplementary crystallographic information

Comment

Isosteviol is a tetracyclic diterpenoid with a beyerane skeleton, which has good pharmacological activity against broad spectrum significant diseases including ischemia-reperfusion injury, hypertension, and cancer (Wong et al., 2004; Liu, et al., 2001; Xu, et al., 2007; Mizushina et al., 2005). The title compound was obtained by esterification of isosteviol. The molecule structure of (I) contains a fused four-ring system A/B/C/D (Fig. 1). The A/B ring and B/C junction are trans-fused, while C/D is cis-fused. Rings A and B adopt chair conformations (Puckering parameters as defined by Cremer & Pople, 1975: Q = 0.554 (4)/0.559 (4) Å, θ= 176.8 (4)/170.4 (4)° and [var phi]= 68 (7)/83 (2)° , respectively), while ring C is in a distorted chair conformation with puckering amplitude Q = 0.647 (4) Å, θ= 18.1 (4)° [var phi]=253.0 (13)°. The distortion may be attributed to the narrowing of the C9—C16—C12 bond angle to 104.2 (3)°. The five-membered ring D adopts an envelope conformation (puckering parameters Q = 0.456 (5)Å, [var phi] = 140.7 (6) °) with atom C16 displaced from the C9/C10/C11/C12 plane by 0.297 (4) Å . The C17—C1—C2—C3 torsion angle of -74.8 (5)° describes the β-orientation of the 4'-bromobutyl ester group with respect to the ent-kaurane nucleus.

Experimental

Isosteviol was obtained by hydrolysis of stevioside with 10% sulfuric acid at 95 °C for 7 h and recrystallization from ethanol gave colorless crystals of isosteviol in 80% yield. A mixture of 1,4-dibromobutane (2.4 ml, 20 mmol), K2CO3 (2.8 g, 20 mmol) and acetonitrile (20 ml) was heated to reflux. Isosteviol (3.2 g, 10 mmol) in 30 ml acetonitrile was added dropwise over 10 min, and the resulting mixture was stirred for 2 h further. The mixture was cooled to room temperature, and then distilled to one third volume under reduced pressure. The residue was poured into ice water, and the aqueous layer was extracted with CH2Cl2 (3 × 50 ml). The combined CH2Cl2 extracts were washed with water (1 × 50 ml) and brine (1 × 50 ml) respectively, and then dried with anhydrous Na2SO4. After the solvent was evaporated, the residue was purified by column chromatography on silica (petroleum ether/ethyl acetate = 18:1, v/v) to give the title compound (2.7 g, 60%). Crystals of the title compound suitable for X-ray diffraction were obtained by slow evaporation of ethanol solution at room temperature. m.p. 372-373 K; 1H NMR(300 MHz, CDCl3), δH ppm: 0.74(s, 3H), 0.90(s, 3H), 1.18(s, 3H), 0.96-2.01(m, 22H), 2.17-2.22(d, 1H, J=15.00 Hz), 2.49-2.56(dd, 1H, J=18.37, 3.57 Hz), 3.53-3.57(t, 2H, J=6.60 Hz), 4.00-4.14(m, 2H).

Refinement

All H atoms were placed in geometrical positions and constrained to ride on their parent atoms with C–H distances in the range 0.96–0.98 Å, and included in the final cycles of refinement using a riding model, with Uiso(H) = 1.5Ueq(C) for methyl H and 1.2Ueq(C) for other H atoms.

Figures

Fig. 1.
The molecular structure of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Crystal data

C24H37BrO3Dx = 1.341 Mg m3
Mr = 453.45Melting point = 372–373 K
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 3390 reflections
a = 7.4335 (10) Åθ = 2.2–20.1°
b = 9.7732 (14) ŵ = 1.85 mm1
c = 30.920 (4) ÅT = 298 K
V = 2246.3 (5) Å3Block, colourless
Z = 40.45 × 0.43 × 0.37 mm
F(000) = 960

Data collection

Bruker SMART CCD area-detector diffractometer3955 independent reflections
Radiation source: fine-focus sealed tube3041 reflections with I > 2/s(I)
graphiteRint = 0.052
phi and ω scansθmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 1999)h = −8→8
Tmin = 0.490, Tmax = 0.548k = −11→11
11802 measured reflectionsl = −25→36

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.042H-atom parameters constrained
wR(F2) = 0.108w = 1/[σ2(Fo2) + (0.0392P)2 + 0.9109P] where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max = 0.001
3955 reflectionsΔρmax = 0.64 e Å3
256 parametersΔρmin = −0.25 e Å3
0 restraintsAbsolute structure: Flack (1983), 1657 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.065 (11)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
Br11.06095 (7)0.65680 (5)0.843138 (17)0.06872 (19)
O10.6425 (6)1.2658 (4)0.55233 (12)0.0896 (14)
O20.4910 (4)0.6155 (3)0.72346 (9)0.0539 (8)
O30.2689 (5)0.7630 (3)0.71082 (10)0.0596 (8)
C10.3384 (5)0.5981 (4)0.65535 (13)0.0409 (9)
C20.4651 (7)0.4761 (4)0.64746 (13)0.0509 (11)
H2A0.46480.41870.67310.061*
H2B0.41740.42220.62380.061*
C30.6590 (7)0.5144 (4)0.63695 (14)0.0500 (11)
H3A0.71500.55390.66240.060*
H3B0.72540.43240.62930.060*
C40.6691 (6)0.6156 (4)0.59994 (14)0.0465 (10)
H4A0.62810.57100.57370.056*
H4B0.79370.64180.59570.056*
C50.5556 (5)0.7466 (4)0.60725 (11)0.0336 (8)
C60.5564 (5)0.8292 (4)0.56375 (11)0.0348 (8)
H60.52870.76220.54110.042*
C70.7413 (6)0.8882 (4)0.55177 (13)0.0463 (11)
H7A0.78220.94680.57510.056*
H7B0.82650.81360.54900.056*
C80.7401 (6)0.9696 (5)0.51008 (14)0.0522 (11)
H8A0.73560.90630.48590.063*
H8B0.85191.02030.50800.063*
C90.5820 (7)1.0706 (4)0.50609 (13)0.0511 (11)
C100.5754 (7)1.1544 (5)0.54781 (14)0.0539 (11)
C110.4664 (6)1.0794 (4)0.58069 (12)0.0403 (10)
H11A0.36061.13200.58860.048*
H11B0.53691.06270.60650.048*
C120.4113 (5)0.9427 (4)0.55920 (11)0.0355 (9)
C130.2273 (5)0.8911 (4)0.57262 (13)0.0431 (10)
H13A0.18460.82600.55130.052*
H13B0.14370.96730.57320.052*
C140.2291 (5)0.8229 (4)0.61678 (13)0.0401 (9)
H14A0.10900.79170.62400.048*
H14B0.26670.88840.63850.048*
C150.3585 (5)0.7013 (4)0.61649 (12)0.0356 (9)
H150.32370.64820.59090.043*
C160.4094 (6)0.9881 (4)0.51133 (12)0.0454 (10)
H16A0.40900.90940.49220.055*
H16B0.30461.04400.50520.055*
C170.3620 (6)0.6695 (5)0.69846 (13)0.0428 (10)
C180.1425 (6)0.5419 (5)0.65644 (17)0.0630 (13)
H18A0.13400.47030.67760.095*
H18B0.11150.50620.62850.095*
H18C0.06110.61450.66390.095*
C190.6359 (5)0.8274 (4)0.64501 (12)0.0404 (9)
H19A0.64880.76840.66960.061*
H19B0.55750.90210.65220.061*
H19C0.75160.86250.63680.061*
C200.5970 (8)1.1571 (5)0.46522 (16)0.0774 (16)
H20A0.59841.09840.44030.116*
H20B0.70611.20960.46610.116*
H20C0.49581.21790.46350.116*
C210.5242 (7)0.6883 (5)0.76431 (14)0.0647 (14)
H21A0.41630.68790.78200.078*
H21B0.55700.78260.75850.078*
C220.6719 (6)0.6183 (5)0.78729 (15)0.0587 (12)
H22A0.63830.52340.79170.070*
H22B0.68570.65990.81560.070*
C230.8505 (7)0.6223 (7)0.76451 (16)0.0757 (16)
H23A0.83860.57750.73670.091*
H23B0.88290.71700.75920.091*
C240.9989 (7)0.5548 (6)0.78940 (17)0.0716 (15)
H24A1.10490.54840.77120.086*
H24B0.96260.46250.79700.086*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Br10.0692 (3)0.0608 (3)0.0761 (3)0.0049 (3)−0.0274 (3)−0.0054 (3)
O10.135 (4)0.054 (2)0.080 (3)−0.039 (2)0.034 (2)−0.0121 (19)
O20.060 (2)0.0612 (19)0.0409 (16)0.0070 (15)−0.0069 (14)−0.0048 (14)
O30.070 (2)0.062 (2)0.0470 (18)0.0160 (19)0.0007 (16)−0.0034 (16)
C10.046 (2)0.040 (2)0.037 (2)−0.0072 (18)−0.004 (2)0.0044 (19)
C20.076 (3)0.034 (2)0.043 (3)0.002 (2)−0.008 (2)0.0040 (18)
C30.062 (3)0.041 (2)0.047 (3)0.016 (2)−0.003 (2)0.003 (2)
C40.043 (2)0.050 (3)0.047 (2)0.011 (2)−0.0043 (19)−0.005 (2)
C50.032 (2)0.0344 (19)0.035 (2)−0.0022 (19)−0.0021 (18)−0.0015 (16)
C60.037 (2)0.0328 (18)0.0346 (19)−0.004 (2)0.0010 (17)−0.0038 (16)
C70.040 (2)0.046 (2)0.053 (3)−0.0039 (19)0.009 (2)−0.006 (2)
C80.053 (3)0.057 (3)0.047 (3)−0.006 (2)0.015 (2)−0.004 (2)
C90.073 (3)0.043 (2)0.037 (2)−0.007 (2)0.009 (2)0.0028 (18)
C100.068 (3)0.039 (2)0.054 (3)−0.006 (3)0.010 (2)−0.002 (2)
C110.048 (3)0.034 (2)0.039 (2)0.0043 (19)0.0012 (19)0.0017 (17)
C120.041 (2)0.038 (2)0.0273 (19)−0.0003 (18)−0.0034 (17)0.0009 (16)
C130.037 (2)0.045 (2)0.047 (2)0.0042 (18)−0.0059 (18)0.007 (2)
C140.029 (2)0.046 (2)0.046 (2)−0.0009 (19)0.0018 (17)0.004 (2)
C150.037 (2)0.039 (2)0.031 (2)−0.0041 (17)−0.0016 (17)−0.0046 (16)
C160.057 (3)0.045 (2)0.035 (2)−0.001 (2)−0.006 (2)0.0011 (18)
C170.044 (2)0.044 (2)0.041 (2)−0.005 (2)−0.0008 (18)0.009 (2)
C180.061 (3)0.069 (3)0.059 (3)−0.029 (2)−0.005 (3)0.009 (3)
C190.037 (2)0.047 (2)0.037 (2)−0.0021 (18)−0.0049 (16)−0.003 (2)
C200.108 (5)0.065 (3)0.060 (3)−0.013 (4)0.020 (3)0.018 (3)
C210.075 (3)0.082 (4)0.037 (2)−0.001 (3)−0.012 (2)−0.006 (2)
C220.059 (3)0.069 (3)0.048 (3)−0.004 (2)−0.004 (2)0.000 (2)
C230.064 (3)0.111 (5)0.052 (3)−0.003 (3)−0.001 (2)0.009 (3)
C240.056 (3)0.091 (4)0.068 (3)−0.004 (3)−0.004 (3)−0.016 (3)

Geometric parameters (Å, °)

Br1—C241.992 (5)C11—C121.547 (5)
O1—C101.206 (5)C11—H11A0.9700
O2—C171.340 (5)C11—H11B0.9700
O2—C211.470 (5)C12—C131.516 (6)
O3—C171.208 (5)C12—C161.545 (5)
C1—C171.515 (6)C13—C141.519 (5)
C1—C21.539 (6)C13—H13A0.9700
C1—C181.557 (6)C13—H13B0.9700
C1—C151.576 (5)C14—C151.529 (5)
C2—C31.524 (6)C14—H14A0.9700
C2—H2A0.9700C14—H14B0.9700
C2—H2B0.9700C15—H150.9800
C3—C41.515 (6)C16—H16A0.9700
C3—H3A0.9700C16—H16B0.9700
C3—H3B0.9700C18—H18A0.9600
C4—C51.549 (5)C18—H18B0.9600
C4—H4A0.9700C18—H18C0.9600
C4—H4B0.9700C19—H19A0.9600
C5—C191.531 (5)C19—H19B0.9600
C5—C151.557 (5)C19—H19C0.9600
C5—C61.569 (5)C20—H20A0.9600
C6—C71.535 (6)C20—H20B0.9600
C6—C121.554 (5)C20—H20C0.9600
C6—H60.9800C21—C221.476 (7)
C7—C81.515 (6)C21—H21A0.9700
C7—H7A0.9700C21—H21B0.9700
C7—H7B0.9700C22—C231.503 (7)
C8—C91.540 (7)C22—H22A0.9700
C8—H8A0.9700C22—H22B0.9700
C8—H8B0.9700C23—C241.499 (7)
C9—C161.524 (6)C23—H23A0.9700
C9—C201.525 (6)C23—H23B0.9700
C9—C101.529 (6)C24—H24A0.9700
C10—C111.492 (6)C24—H24B0.9700
C17—O2—C21115.1 (3)C12—C13—C14112.6 (3)
C17—C1—C2115.2 (3)C12—C13—H13A109.1
C17—C1—C18104.6 (4)C14—C13—H13A109.1
C2—C1—C18107.6 (3)C12—C13—H13B109.1
C17—C1—C15111.4 (3)C14—C13—H13B109.1
C2—C1—C15108.5 (3)H13A—C13—H13B107.8
C18—C1—C15109.3 (3)C13—C14—C15110.0 (3)
C3—C2—C1115.0 (3)C13—C14—H14A109.7
C3—C2—H2A108.5C15—C14—H14A109.7
C1—C2—H2A108.5C13—C14—H14B109.7
C3—C2—H2B108.5C15—C14—H14B109.7
C1—C2—H2B108.5H14A—C14—H14B108.2
H2A—C2—H2B107.5C14—C15—C5111.8 (3)
C4—C3—C2111.6 (4)C14—C15—C1115.7 (3)
C4—C3—H3A109.3C5—C15—C1114.3 (3)
C2—C3—H3A109.3C14—C15—H15104.5
C4—C3—H3B109.3C5—C15—H15104.5
C2—C3—H3B109.3C1—C15—H15104.5
H3A—C3—H3B108.0C9—C16—C12104.2 (3)
C3—C4—C5113.8 (3)C9—C16—H16A110.9
C3—C4—H4A108.8C12—C16—H16A110.9
C5—C4—H4A108.8C9—C16—H16B110.9
C3—C4—H4B108.8C12—C16—H16B110.9
C5—C4—H4B108.8H16A—C16—H16B108.9
H4A—C4—H4B107.7O3—C17—O2121.7 (4)
C19—C5—C4109.0 (3)O3—C17—C1124.1 (4)
C19—C5—C15111.9 (3)O2—C17—C1114.1 (4)
C4—C5—C15107.7 (3)C1—C18—H18A109.5
C19—C5—C6112.8 (3)C1—C18—H18B109.5
C4—C5—C6107.3 (3)H18A—C18—H18B109.5
C15—C5—C6107.9 (3)C1—C18—H18C109.5
C7—C6—C12109.4 (3)H18A—C18—H18C109.5
C7—C6—C5113.8 (3)H18B—C18—H18C109.5
C12—C6—C5116.3 (3)C5—C19—H19A109.5
C7—C6—H6105.5C5—C19—H19B109.5
C12—C6—H6105.5H19A—C19—H19B109.5
C5—C6—H6105.5C5—C19—H19C109.5
C8—C7—C6113.4 (4)H19A—C19—H19C109.5
C8—C7—H7A108.9H19B—C19—H19C109.5
C6—C7—H7A108.9C9—C20—H20A109.5
C8—C7—H7B108.9C9—C20—H20B109.5
C6—C7—H7B108.9H20A—C20—H20B109.5
H7A—C7—H7B107.7C9—C20—H20C109.5
C7—C8—C9114.1 (3)H20A—C20—H20C109.5
C7—C8—H8A108.7H20B—C20—H20C109.5
C9—C8—H8A108.7O2—C21—C22108.3 (4)
C7—C8—H8B108.7O2—C21—H21A110.0
C9—C8—H8B108.7C22—C21—H21A110.0
H8A—C8—H8B107.6O2—C21—H21B110.0
C16—C9—C20116.3 (4)C22—C21—H21B110.0
C16—C9—C1099.6 (3)H21A—C21—H21B108.4
C20—C9—C10113.8 (3)C21—C22—C23114.8 (4)
C16—C9—C8107.2 (3)C21—C22—H22A108.6
C20—C9—C8111.5 (4)C23—C22—H22A108.6
C10—C9—C8107.5 (4)C21—C22—H22B108.6
O1—C10—C11126.1 (4)C23—C22—H22B108.6
O1—C10—C9124.6 (4)H22A—C22—H22B107.5
C11—C10—C9109.2 (4)C24—C23—C22113.5 (4)
C10—C11—C12106.0 (3)C24—C23—H23A108.9
C10—C11—H11A110.5C22—C23—H23A108.9
C12—C11—H11A110.5C24—C23—H23B108.9
C10—C11—H11B110.5C22—C23—H23B108.9
C12—C11—H11B110.5H23A—C23—H23B107.7
H11A—C11—H11B108.7C23—C24—Br1112.2 (4)
C13—C12—C16110.4 (3)C23—C24—H24A109.2
C13—C12—C11114.1 (3)Br1—C24—H24A109.2
C16—C12—C1199.6 (3)C23—C24—H24B109.2
C13—C12—C6111.3 (3)Br1—C24—H24B109.2
C16—C12—C6107.3 (3)H24A—C24—H24B107.9
C11—C12—C6113.2 (3)

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BG2330).

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