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Acta Crystallogr Sect E Struct Rep Online. 2010 August 1; 66(Pt 8): o2040–o2041.
Published online 2010 July 17. doi:  10.1107/S1600536810027352
PMCID: PMC3007447

Pregna-1,4,20-trien-3-one, a cytotoxic marine steroid from the marine soft coral Nephthea sp.

Abstract

The title compound, C21H28O, was isolated from the cytotoxic lipid extract of the Fidjian soft coral Nephthea sp. The steroid showed inhibitory activity to human colon adenocarcinoma SW480 cells (IC50 = 2.5 µg ml−1). The mol­ecular structure indicates that the A ring is almost planar (r.m.s. deviation = 0.032 Å), the B and C rings adopt chair conformations and the five-membered D ring is a half-chair. The B/C and C/D ring junctions are trans-fused.

Related literature

For chemical background to soft corals, see: Coll (1992 [triangle]); Sarma et al. (2009 [triangle]). For the initial isolation of the title compound, see: Kingston et al. (1977 [triangle]); Higgs & Faulkner (1977 [triangle]). For further isolations of the title compound from other organisms, see: Maia et al. (1998 [triangle]); Ciavatta et al. (2004 [triangle]); Zhang et al. (2003 [triangle], 2005 [triangle]). Huang et al. (2006 [triangle], 2009 [triangle]); Yan et al. (2004 [triangle], 2007 [triangle]). For steroid ring conformations, see: Kingston et al. (1979 [triangle]). For further information on the cytotoxicity studies, see: Grever et al. (1992 [triangle]); Ullrich et al. (2009 [triangle]). For a related structure, see: Thompson et al. (1999 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2040-scheme1.jpg

Experimental

Crystal data

  • C21H28O
  • M r = 296.43
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2040-efi1.jpg
  • a = 6.967 (5) Å
  • b = 11.470 (9) Å
  • c = 20.891 (16) Å
  • V = 1669 (2) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.07 mm−1
  • T = 100 K
  • 0.32 × 0.16 × 0.06 mm

Data collection

  • Bruker X8 Kappa APEXII diffractometer
  • 7256 measured reflections
  • 2267 independent reflections
  • 1144 reflections with I > 2σ(I)
  • R int = 0.142

Refinement

  • R[F 2 > 2σ(F 2)] = 0.063
  • wR(F 2) = 0.142
  • S = 0.97
  • 2267 reflections
  • 202 parameters
  • H-atom parameters constrained
  • Δρmax = 0.25 e Å−3
  • Δρmin = −0.26 e Å−3

Data collection: APEX2 (Bruker, 2009 [triangle]); cell refinement: SAINT (Bruker, 2009 [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: DIAMOND (Brandenburg, 1999 [triangle]); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810027352/hb5516sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810027352/hb5516Isup2.hkl

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

Acknowledgments

We appreciate the help of A. D. Wright, University of Hawaii at Hilo, concerning collection of the coral material and would like to thank W. Beil and his team at the Institute for Clinical Pharmacology, Hannover Medical School, for initial cytotoxicity screening of the crude extract and fractions. Furthermore, the authors gratefully acknowledge J. Herrmann and R. Müller, Helmholtz Institute for Pharmaceutical Research Saarland/Saarland University, Department of Pharmaceutical Biotechnology, Saarbrücken, for the determination of the cytotoxicity of the pure pregnatriene-one. GS thanks A. C. Filippou for support.

supplementary crystallographic information

Comment

Soft corals of the genus Nephthea are rich in sesqui- and di-terpenoids (Coll, 1992) and steroids (Sarma et al., 2009). As part of our search for bioactive substances from Fidjian marine invertebrates, the soft coral Nephthea sp. (Figure 1) was studied as its CH2Cl2 extract showed in an initial screening significant cytotoxicity to gastric adenocarcinoma HM02 (IC50 = 2.1 µg/ml), hepatocellular carcinoma HepG2 (IC50 = 3.2 µg/ml), and breast adenocarcinoma MCF7 (IC50 = 4.0 µg/ml) cell lines. Bioassay-guided fractionation resulted in the isolation of pregna-1,4,20-triene-3-one as the major secondary metabolite. X-ray analysis confirmed the structure proposed on the basis of spectral evidence, primarily NMR. Pregna-1,4,20-triene-3-one was first isolated independently in parallel by the groups of Fallis (Kingston et al., 1977) and Faulkner (Higgs & Faulkner, 1977) from the sea raspberry Gersemia rubiformis and an unidentified soft coral, respectively. Later on, the steroid was also obtained from soft corals of the genus Carijoa (Maia et al., 1998; Ciavatta et al., 2004), Cladiella (Zhang et al., 2003; Huang et al., 2006; Huang et al., 2009), Sinularia (Zhang et al., 2005) and Spongodes (Yan et al., 2004; Yan et al., 2007). However, this is the first time that pregna-1,4,20-triene-3-one has been isolated from a soft coral of the genus Nephthea. The molecule contains a fused four-ring system A/B/C/D (Figure 2). Ring A with two double bonds is highly planar (Thompson et al., 1999), whereas the cyclohexane rings B and C adopt chair conformations. The five membered ring D exhibits a half-chair form. The B/C and C/D ring junctions are trans-fused. The methyl substituents at atoms C-10 and C-13 are oriented to the same side of the steroid nucleus. The vinyl group at C17 is attached equatorially to ring D. The absolute configuration could not be determined by x-ray, but could be established by direct comparison of optical rotation and 1H NMR and 13C NMR data with literature data (Ciavatta et al., 2004; Higgs & Faulkner, 1977; Kingston et al., 1977 and 1979).

Despite its frequent occurrence and isolation of this metabolite, a biological activity was never attributed to its molecular structure. The cytotoxic effects of purified pregna-1,4,20-triene-3-one against mouse NIH/3 T3 and human SW480 (human colon adenocarcinoma) cell lines was investigated, and the compound showed no activity towards NIH/3 T3 tumor cells, but significant growth inhibitory activity towards SW480 tumor cells (IC50 = 2.5 µg/ml). Sterols, particularly highly oxygenated steroids have been reported to be cytotoxic towards several cancer cell lines. However, in contrast to the examples known from the literature, it is noteworthy that pregna-1,4,20-triene-3-one exhibits cytotoxicity with its solely mono-oxygenated structure featuring a rare vinyl group at C-17.

Experimental

Animal material

The soft coral Nephthea sp. (Figure 1) was collected in 1999 from Fiji Islands and stored in EtOH at -20°C until workup. A voucher specimen has been deposited at the Institute for Pharmaceutical Biology, University of Bonn, voucher number CT199 NNNN.

Extraction and isolation

The freeze-dried soft coral Nephthea sp. (250 g dry wt) was extracted repeatedly with CH2Cl2/MeOH (2:1, v/v) to produce 10.5 g of crude organic extract. A portion of the extract (5 g) was subjected to normal phase vacuum liquid chromatography (VLC), using stepwise gradient elution from hexanes containing increasing proportions of EtOAc followed by MeOH, to produce nine subfractions. The fraction eluting with 60% EtOAc in hexanes was found to be most active in cancer cell line assays. This fraction was further chromatographed on RP18 solid phase extraction (SPE) cartridges using a stepwise gradient solvent system of decreasing polarity starting from 70% aqueous MeCN to 100% MeCN. The most active fraction after SPE was then purified by normal phase HPLC [Knauer Eurospher-100Si-5 µm (250 x 8 mm), petroleum ether / acetone (85:15), 1.5 ml/min, refraction index detection] giving pure pregna-1,4,20-triene-3-one (9.3 mg). Colorless needles of (I) were prepared by slow evaporation from a methanol solution.

Spectroscopic data

EI—MS: m/e (rel. abundance) 296 (27), 122 (100), 91 (14), 79 (7).

1H NMR (300 MHz, CDCl3): δ 7.06 (H-1, d, 10.2), 6.21 (H-2, dd, 10.2, 1.7), 6.06 (H-4, t, 1.7), 5.73 (H-20, ddd, 16.7, 10.7, 7.7), 4.98 (H-21a, dd, 10.7, 1.5), 4.93 (H-21b, dd, 16.7, 1.5), 2.47 (H-6ax, m), 2.36 (H-6eq, m), 1.95 (H-7a, m), 1.95 (H-17, m), 1.78 (H-16a, m), 1.72 (12a, m), 1.68 (H2-11, m), 1.68 (H-15a, m), 1.62 (H-8, m), 1.56 (H-16b, m), 1.24 (H-15b, m), 1.22 (H3-19, s), 1.06 (H-9, m), 1.05 (H-12b, m), 1.04 (H-7 b, m), 0.99 (H-14, m), 0.65 (H3-18, s).

13C NMR (75 MHz, CDCl3): δ 186.4 (C-3, s), 169.4 (C-5, s), 156.0 (C-1, d), 139.3 (C-20, d), 127.4 (C-2, d), 123.8 (C-4, d), 114.9 (C-21, t), 55.1 (C-17, d), 54.6 (C-14, d), 52.7 (C-9, d), 43.6 (C-10, s and C-13, s), 37.1 (C-12, t), 35.6 (C-8, d), 33.7 (C-7, t), 32.9 (C-6, t), 27.1 (C-16, t), 24.9 (C-15, t), 22.5 (C-11, t), 18.7 (C-19, q), 12.9 (C-18, q).

Optical rotation

[α]20D +35° (CHCl3, c = 0.37)

Cytotoxicity Assay

Initial cytotoxic activity of the crude extract towards HM02, HepG2, and MCF7 cancer cell lines were determined by standard procedures (Grever et al., 1992). Human SW-480 (colon adenocarcinoma) and mouse NIH-3 T3 (Swiss mouse embryo) cell lines were obtained from the German Collection of Microorganisms and Cell Cultures (DSMZ) and cultured under conditions recommended by the depositor. The cytotoxicity of pregna-1,4,20-triene-3-one was determined in a viability assay using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) as described elsewhere (Ullrich et al., 2009).

Refinement

All hydrogen atoms were placed in calculated positions with C—H distances ranging from 0.95 to 0.99Å and included in the refinement in riding motion approximation, with Uiso = 1.2 Ueq of the carrier atom.

Due to the absence of any significant anomalous scatterers in the compound, the absolute configuration could not be determined from the diffraction data. All Friedel equivalents were merged before the final refinement.

Figures

Fig. 1.
Macroscopic picture of Nephthea sp.
Fig. 2.
Molecular structure of Pregna-1,4,20-triene-3-one showing 50% probability displacement ellipsoids (DIAMOND; Brandenburg, 1999).

Crystal data

C21H28OF(000) = 648
Mr = 296.43Dx = 1.179 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 688 reflections
a = 6.967 (5) Åθ = 2.6–24.9°
b = 11.470 (9) ŵ = 0.07 mm1
c = 20.891 (16) ÅT = 100 K
V = 1669 (2) Å3Plate, colourless
Z = 40.32 × 0.16 × 0.06 mm

Data collection

Bruker X8 Kappa APEXII diffractometer1144 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.142
graphiteθmax = 28.0°, θmin = 2.6°
fine slicing [var phi] and ω scansh = −8→9
7256 measured reflectionsk = −10→15
2267 independent reflectionsl = −24→26

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.063H-atom parameters constrained
wR(F2) = 0.142w = 1/[σ2(Fo2) + (0.0414P)2] where P = (Fo2 + 2Fc2)/3
S = 0.97(Δ/σ)max < 0.001
2267 reflectionsΔρmax = 0.25 e Å3
202 parametersΔρmin = −0.26 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.009 (2)

Special details

Experimental. During data collection the crystal was in cold N2 gas of a Kryoflex cooler (Bruker AXS).
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
C10.0756 (6)0.8569 (4)0.1960 (2)0.0264 (11)
H1−0.03010.90900.19350.032*
C20.0531 (6)0.7591 (4)0.2299 (2)0.0279 (12)
H2−0.06620.74460.25050.033*
C30.2060 (6)0.6750 (4)0.2361 (2)0.0285 (11)
C40.3822 (6)0.6981 (4)0.1998 (2)0.0255 (11)
H40.48180.64150.20050.031*
C50.4080 (6)0.7956 (3)0.1657 (2)0.0237 (11)
C60.5879 (6)0.8167 (4)0.1284 (2)0.0272 (11)
H6A0.67490.74900.13290.033*
H6B0.65450.88640.14540.033*
C70.5388 (6)0.8353 (4)0.0578 (2)0.0269 (11)
H7A0.65770.85280.03360.032*
H7B0.48270.76290.04000.032*
C80.3973 (6)0.9350 (4)0.0493 (2)0.0250 (11)
H80.45911.00850.06480.030*
C90.2129 (6)0.9137 (4)0.0890 (2)0.0233 (11)
H90.15450.84040.07190.028*
C100.2575 (6)0.8901 (3)0.1614 (2)0.0229 (11)
C110.0639 (6)1.0103 (4)0.0783 (2)0.0255 (11)
H11A0.11301.08400.09670.031*
H11B−0.05570.98970.10130.031*
C120.0181 (6)1.0290 (3)0.0069 (2)0.0254 (11)
H12A−0.04630.9588−0.01030.031*
H12B−0.07101.09580.00230.031*
C130.2001 (6)1.0527 (3)−0.0312 (2)0.0233 (11)
C140.3411 (6)0.9511 (3)−0.0204 (2)0.0247 (11)
H140.27010.8788−0.03280.030*
C150.4951 (6)0.9686 (4)−0.0717 (2)0.0310 (12)
H15A0.55520.8934−0.08360.037*
H15B0.59611.0227−0.05670.037*
C160.3837 (6)1.0211 (4)−0.1290 (2)0.0336 (12)
H16A0.38080.9654−0.16510.040*
H16B0.44571.0941−0.14360.040*
C170.1756 (6)1.0464 (4)−0.1046 (2)0.0265 (11)
H170.09570.9762−0.11430.032*
C180.2877 (6)1.1710 (3)−0.0131 (2)0.0294 (11)
H18A0.19161.2325−0.01900.044*
H18B0.39881.1868−0.04050.044*
H18C0.32861.16930.03180.044*
C190.3332 (6)1.0012 (4)0.1957 (2)0.0280 (11)
H19A0.37910.98050.23860.042*
H19B0.22941.05840.19930.042*
H19C0.43911.03470.17090.042*
C200.0811 (7)1.1483 (4)−0.1348 (2)0.0325 (12)
H200.15231.2189−0.13660.039*
C21−0.0940 (7)1.1494 (4)−0.1594 (2)0.0394 (13)
H21A−0.17021.0807−0.15850.047*
H21B−0.14351.2188−0.17790.047*
O0.1903 (4)0.5870 (3)0.27010 (17)0.0409 (9)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.027 (2)0.027 (2)0.025 (3)0.004 (2)−0.004 (2)−0.007 (2)
C20.036 (3)0.031 (2)0.016 (3)−0.009 (2)0.004 (2)−0.003 (2)
C30.037 (3)0.029 (2)0.020 (3)−0.001 (2)−0.001 (2)−0.004 (2)
C40.031 (2)0.024 (2)0.022 (3)0.005 (2)0.001 (2)−0.001 (2)
C50.029 (2)0.023 (2)0.019 (3)−0.001 (2)0.000 (2)−0.004 (2)
C60.027 (2)0.029 (2)0.026 (3)0.003 (2)−0.001 (2)0.002 (2)
C70.030 (3)0.032 (2)0.018 (3)0.004 (2)−0.001 (2)0.004 (2)
C80.030 (2)0.025 (2)0.020 (3)−0.001 (2)−0.001 (2)0.002 (2)
C90.027 (2)0.021 (2)0.022 (3)−0.0005 (19)0.006 (2)0.0003 (19)
C100.026 (2)0.029 (2)0.014 (3)−0.0060 (19)−0.001 (2)−0.0012 (19)
C110.030 (2)0.034 (2)0.013 (3)−0.003 (2)0.004 (2)−0.001 (2)
C120.026 (2)0.021 (2)0.029 (3)0.0010 (19)−0.001 (2)0.001 (2)
C130.027 (2)0.024 (2)0.019 (3)−0.002 (2)−0.001 (2)0.001 (2)
C140.032 (3)0.028 (2)0.015 (3)0.0025 (19)0.003 (2)−0.002 (2)
C150.035 (2)0.041 (3)0.017 (3)0.004 (2)0.005 (2)0.004 (2)
C160.037 (3)0.044 (3)0.020 (3)0.008 (2)0.000 (2)0.005 (2)
C170.026 (2)0.030 (2)0.023 (3)−0.001 (2)−0.001 (2)−0.004 (2)
C180.032 (2)0.034 (2)0.023 (3)−0.003 (2)−0.007 (2)0.002 (2)
C190.036 (2)0.032 (2)0.015 (3)−0.003 (2)−0.005 (2)0.000 (2)
C200.038 (3)0.039 (3)0.020 (3)0.002 (2)0.000 (2)0.002 (2)
C210.046 (3)0.046 (3)0.026 (3)0.009 (3)−0.003 (3)0.007 (2)
O0.047 (2)0.0356 (18)0.040 (3)−0.0040 (17)0.0076 (19)0.0089 (18)

Geometric parameters (Å, °)

C1—C21.336 (6)C12—C131.522 (6)
C1—C101.508 (6)C12—H12A0.9900
C1—H10.9500C12—H12B0.9900
C2—C31.443 (6)C13—C181.535 (5)
C2—H20.9500C13—C141.541 (6)
C3—O1.239 (5)C13—C171.545 (6)
C3—C41.466 (6)C14—C151.529 (6)
C4—C51.338 (6)C14—H141.0000
C4—H40.9500C15—C161.548 (6)
C5—C61.495 (6)C15—H15A0.9900
C5—C101.511 (6)C15—H15B0.9900
C6—C71.531 (6)C16—C171.564 (6)
C6—H6A0.9900C16—H16A0.9900
C6—H6B0.9900C16—H16B0.9900
C7—C81.520 (6)C17—C201.483 (6)
C7—H7A0.9900C17—H171.0000
C7—H7B0.9900C19—H19A0.9800
C8—C141.521 (6)C19—H19B0.9800
C8—C91.548 (6)C19—H19C0.9800
C8—H81.0000C18—H18A0.9800
C9—C111.535 (6)C18—H18B0.9800
C9—C101.568 (6)C18—H18C0.9800
C9—H91.0000C20—C211.324 (6)
C10—C191.554 (5)C20—H200.9500
C11—C121.541 (6)C21—H21A0.9500
C11—H11A0.9900C21—H21B0.9500
C11—H11B0.9900
C2—C1—C10124.4 (4)C11—C12—H12A109.4
C2—C1—H1117.8C13—C12—H12B109.4
C10—C1—H1117.8C11—C12—H12B109.4
C1—C2—C3121.5 (4)H12A—C12—H12B108.0
C1—C2—H2119.3C12—C13—C18111.1 (4)
C3—C2—H2119.3C12—C13—C14108.7 (3)
O—C3—C2122.0 (4)C18—C13—C14112.3 (3)
O—C3—C4121.2 (4)C12—C13—C17114.8 (4)
C2—C3—C4116.8 (4)C18—C13—C17109.3 (4)
C5—C4—C3122.6 (4)C14—C13—C17100.3 (3)
C5—C4—H4118.7C8—C14—C15120.5 (4)
C3—C4—H4118.7C8—C14—C13113.3 (4)
C4—C5—C6121.7 (4)C15—C14—C13104.2 (3)
C4—C5—C10122.6 (4)C8—C14—H14105.9
C6—C5—C10115.7 (4)C15—C14—H14105.9
C5—C6—C7109.8 (4)C13—C14—H14105.9
C5—C6—H6A109.7C14—C15—C16103.9 (3)
C7—C6—H6A109.7C14—C15—H15A111.0
C5—C6—H6B109.7C16—C15—H15A111.0
C7—C6—H6B109.7C14—C15—H15B111.0
H6A—C6—H6B108.2C16—C15—H15B111.0
C8—C7—C6111.2 (4)H15A—C15—H15B109.0
C8—C7—H7A109.4C15—C16—C17106.6 (4)
C6—C7—H7A109.4C15—C16—H16A110.4
C8—C7—H7B109.4C17—C16—H16A110.4
C6—C7—H7B109.4C15—C16—H16B110.4
H7A—C7—H7B108.0C17—C16—H16B110.4
C7—C8—C14111.7 (4)H16A—C16—H16B108.6
C7—C8—C9110.9 (3)C20—C17—C13115.7 (4)
C14—C8—C9108.6 (3)C20—C17—C16114.8 (4)
C7—C8—H8108.5C13—C17—C16103.3 (4)
C14—C8—H8108.5C20—C17—H17107.5
C9—C8—H8108.5C13—C17—H17107.5
C11—C9—C8111.7 (3)C16—C17—H17107.5
C11—C9—C10113.5 (4)C10—C19—H19A109.5
C8—C9—C10112.3 (3)C10—C19—H19B109.5
C11—C9—H9106.3H19A—C19—H19B109.5
C8—C9—H9106.3C10—C19—H19C109.5
C10—C9—H9106.3H19A—C19—H19C109.5
C1—C10—C5111.9 (3)H19B—C19—H19C109.5
C1—C10—C19105.8 (4)C13—C18—H18A109.5
C5—C10—C19108.9 (4)C13—C18—H18B109.5
C1—C10—C9109.9 (3)H18A—C18—H18B109.5
C5—C10—C9108.6 (4)C13—C18—H18C109.5
C19—C10—C9111.8 (3)H18A—C18—H18C109.5
C9—C11—C12112.4 (4)H18B—C18—H18C109.5
C9—C11—H11A109.1C21—C20—C17125.5 (4)
C12—C11—H11A109.1C21—C20—H20117.2
C9—C11—H11B109.1C17—C20—H20117.2
C12—C11—H11B109.1C20—C21—H21A120.0
H11A—C11—H11B107.9C20—C21—H21B120.0
C13—C12—C11111.0 (3)H21A—C21—H21B120.0
C13—C12—H12A109.4
C10—C1—C2—C3−0.2 (7)C8—C9—C10—C1969.2 (4)
C1—C2—C3—O176.2 (4)C8—C9—C11—C1253.7 (5)
C1—C2—C3—C4−4.1 (6)C10—C9—C11—C12−178.2 (3)
O—C3—C4—C5−175.9 (4)C9—C11—C12—C13−54.9 (4)
C2—C3—C4—C54.4 (6)C11—C12—C13—C18−68.0 (4)
C3—C4—C5—C6−179.2 (4)C11—C12—C13—C1456.1 (4)
C3—C4—C5—C10−0.4 (7)C11—C12—C13—C17167.4 (3)
C4—C5—C6—C7121.8 (5)C7—C8—C14—C15−54.7 (5)
C10—C5—C6—C7−57.1 (5)C9—C8—C14—C15−177.4 (4)
C5—C6—C7—C856.5 (5)C7—C8—C14—C13−179.1 (3)
C6—C7—C8—C14−177.7 (4)C9—C8—C14—C1358.3 (4)
C6—C7—C8—C9−56.4 (5)C12—C13—C14—C8−60.0 (4)
C7—C8—C9—C11−177.0 (4)C18—C13—C14—C863.4 (5)
C14—C8—C9—C11−53.9 (5)C17—C13—C14—C8179.3 (4)
C7—C8—C9—C1054.2 (5)C12—C13—C14—C15167.2 (3)
C14—C8—C9—C10177.3 (3)C18—C13—C14—C15−69.4 (5)
C2—C1—C10—C54.0 (6)C17—C13—C14—C1546.5 (4)
C2—C1—C10—C19−114.5 (5)C8—C14—C15—C16−161.8 (4)
C2—C1—C10—C9124.7 (4)C13—C14—C15—C16−33.3 (4)
C4—C5—C10—C1−3.6 (6)C14—C15—C16—C177.2 (5)
C6—C5—C10—C1175.3 (4)C12—C13—C17—C2076.7 (5)
C4—C5—C10—C19113.0 (5)C18—C13—C17—C20−48.9 (5)
C6—C5—C10—C19−68.1 (5)C14—C13—C17—C20−167.1 (3)
C4—C5—C10—C9−125.0 (5)C12—C13—C17—C16−157.0 (3)
C6—C5—C10—C953.9 (5)C18—C13—C17—C1677.4 (4)
C11—C9—C10—C158.4 (4)C14—C13—C17—C16−40.8 (4)
C8—C9—C10—C1−173.7 (3)C15—C16—C17—C20148.1 (4)
C11—C9—C10—C5−178.9 (3)C15—C16—C17—C1321.2 (4)
C8—C9—C10—C5−51.0 (4)C13—C17—C20—C21−108.6 (6)
C11—C9—C10—C19−58.7 (5)C16—C17—C20—C21131.2 (5)

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5516).

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