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The title compound, C20H26O5, or ludongnin B, which has been isolated from Rabdosia var lophanthoides, is composed of three six-membered rings and two five-membered rings. The isobenzo­furan ring system couples almost orthogonally to the methano­cyclo­hepta­[c]­pyran moiety through a spiro-C atom.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801015847/ob6077sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801015847/ob6077Isup2.hkl
Contains datablock I

CCDC reference: 175996

Key indicators

  • Single-crystal X-ray study
  • T = 295 K
  • Mean [sigma](C-C) = 0.006 Å
  • R factor = 0.053
  • wR factor = 0.128
  • Data-to-parameter ratio = 10.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes

REFLT_03 From the CIF: _diffrn_reflns_theta_max 28.25 From the CIF: _reflns_number_total 2291 Count of symmetry unique reflns 2291 Completeness (_total/calc) 100.00% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present no Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF.

Comment top

Rabdosia lophanthoides is widely distributed in South and Southeast Asia and has long been used as folk medicine in China. Its concoctions are used for the treatment of acute icteric hepatitis, acute cholecystitis, enteritis, laryngopharyngitis, gynopathy and lepromatous leprosy (Wu & Li, 1977). As the natural diterpenoids isolated from plants which belong to rabdosia category usually have the bioactivity of antibiotic and antitumor (Zhu, 1982), in order to isolate bioactive constituents from this plant, we investigated the whole herb of Rabdosia var lophanthoides, which led to the isolation of the title compound, ()I, the natural diterpenoid ludongnin B. The ludongnin B had been previously isolated from Rabdosia rubescens Hara (Sun et al., 1988; Zheng et al., 1986), its structure was established from the IR, 1H NMR and 13C NMR spectral evidence. This is the first time that ludongnin B has been isolated from Rabdosia lophanthoides, and its structure was confirmed by the X-ray.

The title compound, (I), is composed of three six-membered rings and two five-membered rings (Fig. 1). The cyclohexane ring B (C1—C5/C10) exists in a twist chair conformation owing to the cis fusion with ring A. This is also indicated by the smaller torsion angles C2—C3—C4—C5 of 36.2 (5)°, C3—C4—C5—C10 of -34.3 (4)° and C4—C5—C10—C1 of 45.0 (4)°. Ring C (C7—C10/C20/O2) adopts a sofa conformation with the apex at C10, displaced by 0.745 (5) Å from the mean plane of the remaining five atoms, and ring D (C8—C9/C11—C14) adopts a boat conformation. The two five-membered rings, A (C4—C6/O1/C19) and E (C8/C13—C16), adopt envelope conformations, with C4 and C14 displaced by 0.521 (6) and 0.715 (6) Å, respectively, from the mean plane of the remaining four atoms. The C18 methyl group is equatorial to ring B and the associated torsion angles are 158.1 (4) (C2—C3—C4—C18) and -156.2 (3)° (C18—C4—C5—C10). The isobenzofuran ring system couples almost orthogonally to the methanocyclohepta[c] pyran moiety through a spiro-C atom.

Experimental top

The plant was collected in the mountain near the Shangqiu City, Shanxi province, People's Republic of China. The identity of the plant was confirmed by Dr Li Bao-Lin of Shanxi Normal University. 2 kg of dried powder of the whole herb of Rabdosia var lophanthoides were soaked three times with 95% EtOH at room temperature. The ethanolic extracts were evaporated under reduced pressure, the residue was successively fractioned with petroleum ether, EtOAc and n-BuOH. The residue of EtOAc fraction was subjected to column chromatography over silica gel. The column was eluted with petroleum ether–EtOAc mixture, the crude compound was purified by column chromatography on silica gel with acetone–chloroform mixture to obtain pure title compound, (I), (m.p. 569–571 K). Crystals of (I) were obtained by slow evaporation from an aqueous solution containing chloroform and methanol in a 1:1 ratio at room temperature.

Refinement top

H atoms were placed in the geometrically calculated positions and included in the final refinement in the riding-model approximation with Uiso values equal to 1.2Ueq of the corresponding carrier atom. Since the Flack (1983) parameter was 2(2), the Friedel reflections were merged before the final refinement; the relative stereochemistry is shown in the Scheme and Figures.

Computing details top

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL/PC (Siemens, 1991); software used to prepare material for publication: SHELXTL97.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) showing 50% probability displacement ellipsoids.
[Figure 2] Fig. 2. The crystal-packing diagram of (I) viewed down the b axis. H atoms have been omitted for clarity.
spiro[isobenzofuran-4 (1H),4'(3'H)-[1H-7,9a] methanocyclohepta[c]pyran]-1',3,9'(3aH,4'aH)-trione, octahydro-7a,8'-dimethyl top
Crystal data top
C20H26O5Dx = 1.315 Mg m3
Mr = 346.41Melting point: 569-571K K
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
a = 7.569 (2) ÅCell parameters from 29 reflections
b = 9.397 (2) Åθ = 3.3–12.2°
c = 12.310 (3) ŵ = 0.09 mm1
β = 92.62 (2)°T = 295 K
V = 874.6 (4) Å3Prism, colorless
Z = 20.42 × 0.34 × 0.14 mm
F(000) = 372
Data collection top
Siemens P4
diffractometer
Rint = 0.023
Radiation source: normal-focus sealed tubeθmax = 28.3°, θmin = 1.7°
Graphite monochromatorh = 010
ω scansk = 012
2561 measured reflectionsl = 1616
2291 independent reflections3 standard reflections every 97 reflections
1206 reflections with I > 2σ(I) intensity decay: 2.9%
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.053 w = 1/[σ2(Fo2) + (0.0602P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.128(Δ/σ)max < 0.001
S = 0.87Δρmax = 0.24 e Å3
2291 reflectionsΔρmin = 0.18 e Å3
228 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.017 (4)
Primary atom site location: structure-invariant direct methodsAbsolute structure: see text
Secondary atom site location: difference Fourier map
Crystal data top
C20H26O5V = 874.6 (4) Å3
Mr = 346.41Z = 2
Monoclinic, P21Mo Kα radiation
a = 7.569 (2) ŵ = 0.09 mm1
b = 9.397 (2) ÅT = 295 K
c = 12.310 (3) Å0.42 × 0.34 × 0.14 mm
β = 92.62 (2)°
Data collection top
Siemens P4
diffractometer
Rint = 0.023
2561 measured reflections3 standard reflections every 97 reflections
2291 independent reflections intensity decay: 2.9%
1206 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0531 restraint
wR(F2) = 0.128H-atom parameters constrained
S = 0.87Δρmax = 0.24 e Å3
2291 reflectionsΔρmin = 0.18 e Å3
228 parametersAbsolute structure: see text
Special details top

Experimental. IR(KBr) νmax: 1747, 1721 cm-1. no UV absorption. 13C NMR (125 MHz, pyridine): δ (p.p.m.) 215.2(C), 176.2(C), 171.1(C), 76.3(CH2), 69.1(CH2), 57.3(C), 51.0(CH), 48.9(CH), 42.9(CH), 39.2(C), 38.9(C), 35.7(CH), 31.9(CH2), 30.4(CH2), 29.6(2*CH2), 25.1(CH3), 18.0(CH2), 17.5(CH2), 16.5(CH3).

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) top
xyzUiso*/Ueq
O10.6597 (4)0.8513 (3)1.0259 (2)0.0551 (9)
O20.3713 (4)0.8213 (4)0.6934 (3)0.0560 (9)
O30.5983 (4)0.6198 (4)1.0273 (3)0.0670 (11)
O40.2426 (4)0.7159 (5)0.5532 (2)0.0691 (10)
O50.1478 (3)0.5268 (4)0.7755 (2)0.0538 (9)
C10.7476 (5)0.7709 (4)0.6820 (3)0.0413 (11)
H1A0.84680.70750.67230.050*
H1B0.67270.76820.61600.050*
C20.8163 (6)0.9219 (5)0.6999 (4)0.0525 (12)
H2A0.87230.95480.63520.063*
H2B0.71850.98510.71360.063*
C30.9479 (5)0.9245 (5)0.7955 (3)0.0482 (11)
H3A0.97781.02290.81170.058*
H3B1.05520.87740.77450.058*
C40.8858 (5)0.8539 (4)0.8997 (3)0.0353 (9)
C50.7698 (4)0.7204 (4)0.8812 (3)0.0304 (8)
H50.84650.63640.88060.036*
C60.6681 (6)0.7189 (6)0.9843 (3)0.0475 (11)
C70.3358 (5)0.7048 (6)0.6345 (4)0.0484 (11)
C80.4117 (5)0.5627 (5)0.6710 (3)0.0389 (11)
C90.5709 (5)0.5640 (4)0.7592 (3)0.0356 (10)
H90.52130.53450.82780.043*
C100.6417 (4)0.7174 (5)0.7778 (3)0.0304 (8)
C110.7056 (5)0.4510 (5)0.7318 (4)0.0537 (13)
H11A0.79100.44130.79260.064*
H11B0.76880.48210.66930.064*
C120.6222 (6)0.3059 (5)0.7070 (4)0.0572 (13)
H12A0.70760.24570.67270.069*
H12B0.59200.26080.77460.069*
C130.4565 (5)0.3184 (5)0.6326 (4)0.0491 (12)
H130.45260.24150.57870.059*
C140.4519 (5)0.4614 (6)0.5765 (3)0.0527 (13)
H14A0.35960.46510.51930.063*
H14B0.56470.48360.54620.063*
C150.2615 (5)0.4759 (6)0.7234 (3)0.0463 (12)
C160.2857 (6)0.3197 (6)0.6958 (5)0.0654 (15)
H160.30980.26840.76420.078*
C170.1287 (7)0.2563 (7)0.6424 (6)0.108 (3)
H17A0.09160.31300.58060.129*
H17B0.03540.25240.69260.129*
H17C0.15580.16170.61880.129*
C181.0503 (5)0.8124 (5)0.9721 (3)0.0520 (12)
H18A1.01290.76901.03790.078*
H18B1.11850.89610.98970.078*
H18C1.12130.74630.93380.078*
C190.7665 (6)0.9488 (5)0.9650 (4)0.0498 (12)
H19A0.83631.01001.01380.060*
H19B0.69221.00780.91700.060*
C200.4783 (5)0.8075 (5)0.7926 (3)0.0458 (11)
H20A0.40820.76470.84790.055*
H20B0.51430.90140.81780.055*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0577 (19)0.058 (2)0.0513 (19)0.0063 (17)0.0189 (15)0.0134 (17)
O20.0417 (16)0.056 (2)0.069 (2)0.0167 (17)0.0127 (15)0.0020 (19)
O30.077 (2)0.074 (3)0.051 (2)0.031 (2)0.0151 (18)0.0030 (19)
O40.0596 (19)0.089 (3)0.0572 (19)0.006 (2)0.0179 (16)0.019 (2)
O50.0317 (14)0.074 (2)0.0566 (19)0.0000 (17)0.0091 (14)0.0068 (18)
C10.038 (2)0.046 (3)0.041 (2)0.006 (2)0.0038 (19)0.001 (2)
C20.055 (3)0.051 (3)0.052 (3)0.009 (2)0.008 (2)0.001 (2)
C30.047 (2)0.045 (3)0.053 (3)0.017 (2)0.009 (2)0.003 (2)
C40.0347 (19)0.036 (2)0.035 (2)0.0030 (18)0.0040 (16)0.0047 (18)
C50.0312 (18)0.029 (2)0.0307 (19)0.0026 (19)0.0019 (15)0.000 (2)
C60.048 (2)0.051 (3)0.043 (2)0.006 (3)0.0012 (19)0.002 (3)
C70.0263 (19)0.069 (3)0.049 (3)0.003 (3)0.0009 (19)0.008 (3)
C80.0248 (19)0.055 (3)0.037 (2)0.0037 (19)0.0008 (17)0.000 (2)
C90.0294 (19)0.042 (3)0.035 (2)0.0048 (18)0.0008 (16)0.002 (2)
C100.0251 (17)0.034 (2)0.0320 (19)0.0055 (19)0.0028 (14)0.002 (2)
C110.046 (2)0.040 (3)0.073 (3)0.004 (2)0.018 (2)0.014 (2)
C120.059 (3)0.046 (3)0.065 (3)0.012 (3)0.006 (2)0.009 (3)
C130.040 (2)0.055 (3)0.053 (3)0.006 (2)0.005 (2)0.018 (3)
C140.039 (2)0.079 (4)0.040 (2)0.003 (3)0.0001 (19)0.014 (3)
C150.027 (2)0.068 (3)0.044 (2)0.006 (2)0.0003 (18)0.009 (2)
C160.054 (3)0.066 (4)0.077 (3)0.021 (3)0.018 (3)0.017 (3)
C170.064 (3)0.097 (6)0.165 (7)0.034 (4)0.029 (4)0.033 (5)
C180.047 (2)0.051 (3)0.057 (3)0.008 (2)0.010 (2)0.003 (3)
C190.054 (3)0.041 (3)0.056 (3)0.002 (2)0.016 (2)0.007 (2)
C200.036 (2)0.046 (3)0.055 (3)0.008 (2)0.002 (2)0.006 (2)
Geometric parameters (Å, º) top
O1—C61.348 (6)C9—C101.551 (6)
O1—C191.453 (5)C9—H90.9800
O2—C71.334 (6)C10—C201.516 (5)
O2—C201.439 (5)C11—C121.527 (6)
O3—C61.205 (6)C11—H11A0.9700
O4—C71.203 (5)C11—H11B0.9700
O5—C151.196 (5)C12—C131.524 (6)
C1—C21.524 (6)C12—H12A0.9700
C1—C101.540 (5)C12—H12B0.9700
C1—H1A0.9700C13—C141.510 (7)
C1—H1B0.9700C13—C161.539 (6)
C2—C31.507 (6)C13—H130.9800
C2—H2A0.9700C14—H14A0.9700
C2—H2B0.9700C14—H14B0.9700
C3—C41.537 (5)C15—C161.520 (7)
C3—H3A0.9700C16—C171.459 (7)
C3—H3B0.9700C16—H160.9800
C4—C191.524 (6)C17—H17A0.9600
C4—C51.542 (5)C17—H17B0.9600
C4—C181.548 (5)C17—H17C0.9600
C5—C61.514 (5)C18—H18A0.9600
C5—C101.566 (5)C18—H18B0.9600
C5—H50.9800C18—H18C0.9600
C7—C81.514 (7)C19—H19A0.9700
C8—C141.544 (6)C19—H19B0.9700
C8—C151.562 (6)C20—H20A0.9700
C8—C91.584 (5)C20—H20B0.9700
C9—C111.521 (6)
C6—O1—C19110.4 (3)C9—C11—H11A109.0
C7—O2—C20118.6 (4)C12—C11—H11A109.0
C2—C1—C10112.3 (3)C9—C11—H11B109.0
C2—C1—H1A109.1C12—C11—H11B109.0
C10—C1—H1A109.1H11A—C11—H11B107.8
C2—C1—H1B109.1C13—C12—C11111.9 (4)
C10—C1—H1B109.1C13—C12—H12A109.2
H1A—C1—H1B107.9C11—C12—H12A109.2
C3—C2—C1109.7 (4)C13—C12—H12B109.2
C3—C2—H2A109.7C11—C12—H12B109.2
C1—C2—H2A109.7H12A—C12—H12B107.9
C3—C2—H2B109.7C14—C13—C12110.2 (4)
C1—C2—H2B109.7C14—C13—C16102.8 (4)
H2A—C2—H2B108.2C12—C13—C16112.6 (4)
C2—C3—C4115.3 (3)C14—C13—H13110.4
C2—C3—H3A108.4C12—C13—H13110.4
C4—C3—H3A108.4C16—C13—H13110.4
C2—C3—H3B108.4C13—C14—C8101.9 (3)
C4—C3—H3B108.4C13—C14—H14A111.4
H3A—C3—H3B107.5C8—C14—H14A111.4
C19—C4—C3113.5 (4)C13—C14—H14B111.4
C19—C4—C5101.9 (3)C8—C14—H14B111.4
C3—C4—C5115.0 (3)H14A—C14—H14B109.3
C19—C4—C18108.9 (3)O5—C15—C16127.1 (4)
C3—C4—C18108.7 (3)O5—C15—C8124.6 (5)
C5—C4—C18108.5 (3)C16—C15—C8108.3 (4)
C6—C5—C4101.1 (3)C17—C16—C15113.0 (5)
C6—C5—C10111.2 (3)C17—C16—C13117.0 (4)
C4—C5—C10117.5 (3)C15—C16—C13103.5 (4)
C6—C5—H5108.9C17—C16—H16107.6
C4—C5—H5108.9C15—C16—H16107.6
C10—C5—H5108.9C13—C16—H16107.6
O3—C6—O1121.1 (4)C16—C17—H17A109.5
O3—C6—C5128.8 (5)C16—C17—H17B109.5
O1—C6—C5110.1 (4)H17A—C17—H17B109.5
O4—C7—O2118.5 (5)C16—C17—H17C109.5
O4—C7—C8121.6 (5)H17A—C17—H17C109.5
O2—C7—C8119.9 (3)H17B—C17—H17C109.5
C7—C8—C14113.9 (4)C4—C18—H18A109.5
C7—C8—C15108.0 (3)C4—C18—H18B109.5
C14—C8—C1599.3 (4)H18A—C18—H18B109.5
C7—C8—C9117.6 (4)C4—C18—H18C109.5
C14—C8—C9110.5 (3)H18A—C18—H18C109.5
C15—C8—C9105.4 (3)H18B—C18—H18C109.5
C11—C9—C10116.8 (3)O1—C19—C4105.1 (3)
C11—C9—C8109.9 (3)O1—C19—H19A110.7
C10—C9—C8110.8 (3)C4—C19—H19A110.7
C11—C9—H9106.2O1—C19—H19B110.7
C10—C9—H9106.2C4—C19—H19B110.7
C8—C9—H9106.2H19A—C19—H19B108.8
C20—C10—C1111.5 (3)O2—C20—C10112.3 (3)
C20—C10—C9105.0 (3)O2—C20—H20A109.1
C1—C10—C9112.2 (3)C10—C20—H20A109.1
C20—C10—C5111.8 (3)O2—C20—H20B109.1
C1—C10—C5107.0 (3)C10—C20—H20B109.1
C9—C10—C5109.5 (3)H20A—C20—H20B107.9
C9—C11—C12113.1 (3)
C10—C1—C2—C364.8 (4)C8—C9—C10—C5168.1 (3)
C1—C2—C3—C450.5 (5)C6—C5—C10—C2038.5 (5)
C2—C3—C4—C1980.6 (5)C4—C5—C10—C2077.3 (4)
C2—C3—C4—C536.2 (5)C6—C5—C10—C1160.7 (4)
C2—C3—C4—C18158.1 (4)C4—C5—C10—C145.0 (4)
C19—C4—C5—C632.2 (4)C6—C5—C10—C977.4 (4)
C3—C4—C5—C6155.4 (4)C4—C5—C10—C9166.8 (3)
C18—C4—C5—C682.6 (4)C10—C9—C11—C12175.9 (4)
C19—C4—C5—C1089.0 (4)C8—C9—C11—C1248.6 (5)
C3—C4—C5—C1034.3 (4)C9—C11—C12—C1344.5 (6)
C18—C4—C5—C10156.2 (3)C11—C12—C13—C1417.5 (5)
C19—O1—C6—O3175.1 (4)C11—C12—C13—C1696.6 (5)
C19—O1—C6—C56.0 (5)C12—C13—C14—C871.5 (4)
C4—C5—C6—O3156.4 (4)C16—C13—C14—C848.7 (4)
C10—C5—C6—O378.0 (6)C7—C8—C14—C13159.4 (3)
C4—C5—C6—O124.8 (4)C15—C8—C14—C1344.9 (4)
C10—C5—C6—O1100.8 (4)C9—C8—C14—C1365.6 (4)
C20—O2—C7—O4178.1 (4)C7—C8—C15—O534.9 (5)
C20—O2—C7—C81.6 (6)C14—C8—C15—O5153.9 (4)
O4—C7—C8—C1432.3 (6)C9—C8—C15—O591.6 (5)
O2—C7—C8—C14147.9 (4)C7—C8—C15—C16144.6 (4)
O4—C7—C8—C1576.9 (5)C14—C8—C15—C1625.6 (5)
O2—C7—C8—C15102.8 (4)C9—C8—C15—C1688.8 (4)
O4—C7—C8—C9164.0 (4)O5—C15—C16—C1754.9 (7)
O2—C7—C8—C916.3 (6)C8—C15—C16—C17124.7 (5)
C7—C8—C9—C11140.4 (4)O5—C15—C16—C13177.6 (4)
C14—C8—C9—C117.2 (5)C8—C15—C16—C132.9 (5)
C15—C8—C9—C1199.1 (4)C14—C13—C16—C1793.7 (6)
C7—C8—C9—C109.8 (5)C12—C13—C16—C17147.8 (6)
C14—C8—C9—C10123.3 (4)C14—C13—C16—C1531.4 (5)
C15—C8—C9—C10130.3 (4)C12—C13—C16—C1587.1 (5)
C2—C1—C10—C2062.2 (4)C6—O1—C19—C415.9 (4)
C2—C1—C10—C9179.7 (3)C3—C4—C19—O1154.3 (3)
C2—C1—C10—C560.2 (4)C5—C4—C19—O130.1 (4)
C11—C9—C10—C20174.8 (3)C18—C4—C19—O184.4 (4)
C8—C9—C10—C2048.0 (4)C7—O2—C20—C1046.5 (5)
C11—C9—C10—C153.6 (4)C1—C10—C20—O252.5 (5)
C8—C9—C10—C173.2 (4)C9—C10—C20—O269.3 (4)
C11—C9—C10—C565.0 (4)C5—C10—C20—O2172.1 (3)

Experimental details

Crystal data
Chemical formulaC20H26O5
Mr346.41
Crystal system, space groupMonoclinic, P21
Temperature (K)295
a, b, c (Å)7.569 (2), 9.397 (2), 12.310 (3)
β (°) 92.62 (2)
V3)874.6 (4)
Z2
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.42 × 0.34 × 0.14
Data collection
DiffractometerSiemens P4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2561, 2291, 1206
Rint0.023
(sin θ/λ)max1)0.666
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.128, 0.87
No. of reflections2291
No. of parameters228
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.24, 0.18
Absolute structureSee text

Computer programs: XSCANS (Siemens, 1994), XSCANS, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP in SHELXTL/PC (Siemens, 1991), SHELXTL97.

Selected torsion angles (º) top
C2—C3—C4—C536.2 (5)C18—C4—C5—C10156.2 (3)
C2—C3—C4—C18158.1 (4)C4—C5—C10—C145.0 (4)
C3—C4—C5—C1034.3 (4)
 

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