organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 4| April 2013| Pages o467-o468

The furan­osteroid viridiol

aDepartment of Chemistry, Uppsala BioCenter, P.O. Box 7015, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
*Correspondence e-mail: daniel.lundberg@slu.se

(Received 18 January 2013; accepted 26 February 2013; online 2 March 2013)

The asymmetric unit of the title compound, C20H18O6 (systematic name: 1β,3β-dihy­droxy-2β-meth­oxyfuro[4′,3′,2′:4,5,6]-18-norandrosta-8,11,13-triene-7,17-dione), a dihydro derivative of the fungal steroid viridin, contains two mol­ecules with similar conformations. The rings bearing the hy­droxy groups adopt boat conformations. The absolute structure was assigned based on the known chirality of a precursor compound. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds, generating a three-dimensional network and weak C—H⋯O inter­actions consolidate the packing.

Related literature

For background to fungal metabolites, see: Brian & McGowan (1945[Brian, P. W. & McGowan, J. C. (1945). Nature, 156, 144-145.]); Moffatt et al. (1969[Moffatt, J. S., Bu'Lock, J. D. & Yuen, T. H. (1969). J. Chem. Soc. D, p. 839a.]); Jones & Hancock (1987[Jones, R. W. & Hancock, J. G. (1987). Can. J. Microbiol. 33, 963-966.]); Hanson (1995[Hanson, J. R. (1995). Nat. Prod. Rep. 12, 381-384.]); Cross et al. (1995[Cross, M. J., Stewart, A., Hodgkin, M. N., Kerr, D. J. & Wakelam, M. J. O. (1995). J. Biol. Chem. 270, 25352-25355.]); Przybyl (2002[Przybyl, K. (2002). For. Pathol. 32, 387-394.]); Smith et al. (2009[Smith, A., Blois, J., Yuan, H., Aikawa, E., Ellson, C., Figueiredo, J. L., Weissleder, R., Kohler, R., Yaffe, M. B., Cantley, L. C. & Josephson, L. (2009). Mol. Cancer Ther. 8, 1666-1675.]); Andersson et al. (2010[Andersson, P. F., Johansson, S. B. K., Stenlid, J. & Broberg, A. (2010). For. Pathol. 40, 43-46.]); Queloz et al. (2011[Queloz, V., Grunig, C. R., Berndt, R., Kowalski, T., Sieber, T. N. & Holdenrieder, O. (2011). For. Pathol. 41, 133-142.]); Andersson (2012[Andersson, P. F. (2012). PhD thesis, Swedish University of Agricultural Sciences, Uppsala, Sweden. Available at http://pub.epsilon.slu.se/8996 .]); Andersson et al. (2012[Andersson, P. F., Bengtsson, S., Stenlid, J. & Broberg, A. (2012). Molecules, 17, 7769-7781.], 2013[Andersson, P. F., Bengtsson, S., Cleary, M. R., Stenlid, J. & Broberg, A. (2013). Phytochemistry, 86, 195-200.]). For related structures, see: Neidle et al. (1972[Neidle, S., Rogers, D. & Hursthouse, M. B. (1972). J. Chem. Soc. Perkin Trans. 2, pp. 760-766.]); Lang et al. (2009[Lang, Y., Souza, F. E. S., Xu, X., Taylor, N. J., Assoud, A. & Rodrigo, R. (2009). J. Org. Chem. 74, 5429-5439.]). For other characterization methods, see: Brian et al. (1957[Brian, P. W., Curtis, P. J., Hemming, H. G. & Norris, G. L. F. (1957). Trans. Br. Mycol. Soc. 40, 365-368.]); Aldridge et al. (1975[Aldridge, D. C., Turner, W. B., Geddes, A. J. & Sheldrick, B. (1975). J. Chem. Soc. Perkin Trans. 1, pp. 943-945.]); Blight & Grove (1986[Blight, M. M. & Grove, J. F. (1986). J. Chem. Soc. Perkin Trans. 1, pp. 1317-1322.]). For background to the assignment of the absolute structure of the title compound, see: MacMillan et al. (1972[MacMillan, J., Simpson, T. J., Vanstone, A. E. & Yeboah, S. K. (1972). J. Chem. Soc. Perkin Trans. 1, pp. 2892-2898.]); Harrison (1990[Harrison, D. M. (1990). Nat. Prod. Rep. 7, 459-484.]); Dewick (2002[Dewick, P. M. (2002). Nat. Prod. Rep. 19, 181-222.]); Wipf & Kerekes (2003[Wipf, P. & Kerekes, A. D. (2003). J. Nat. Prod. 66, 716-718.]); Flack & Bernardinelli (2000[Flack, H. D. & Bernardinelli, G. (2000). J. Appl. Cryst. 33, 1143-1148.]).

[Scheme 1]

Experimental

Crystal data
  • C20H18O6

  • Mr = 354.34

  • Orthorhombic, P 21 21 21

  • a = 6.8285 (2) Å

  • b = 20.1939 (6) Å

  • c = 22.4344 (6) Å

  • V = 3093.57 (15) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.11 mm−1

  • T = 93 K

  • 0.3 × 0.25 × 0.2 mm

Data collection
  • Oxford Diffraction XcaliburIII Sapphire-3 CCD diffractometer

  • Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007[Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]) Tmin = 0.891, Tmax = 1.000

  • 26916 measured reflections

  • 4874 independent reflections

  • 3294 reflections with I > 2σ(I)

  • Rint = 0.085

Refinement
  • R[F2 > 2σ(F2)] = 0.049

  • wR(F2) = 0.089

  • S = 0.91

  • 4874 reflections

  • 485 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.33 e Å−3

  • Δρmin = −0.25 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O19A—H19A⋯O19Bi 0.85 (3) 2.08 (3) 2.886 (3) 160 (3)
O19B—H19B⋯O20Aii 0.83 (3) 2.30 (3) 3.002 (3) 143 (3)
O20A—H20A⋯O25Biii 0.91 (3) 1.85 (3) 2.717 (3) 160 (3)
O20B—H20B⋯O24Aiv 0.81 (3) 2.05 (3) 2.842 (3) 166 (3)
C2A—H2A⋯O23Bv 1.00 2.45 3.325 (3) 146
C2B—H2B⋯O23A 1.00 2.38 3.295 (3) 151
C11A—H11A⋯O19A 0.95 2.43 3.084 (3) 126
C11B—H11B⋯O19B 0.95 2.58 3.230 (3) 126
C18A—H18A⋯O20A 0.98 2.38 3.227 (3) 145
C18B—H18D⋯O20B 0.98 2.39 3.241 (4) 145
C21A—H21A⋯O24Avi 0.95 2.37 3.282 (3) 162
C21B—H21B⋯O24Bvii 0.95 2.25 3.180 (3) 167
Symmetry codes: (i) [-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (ii) [-x+{\script{1\over 2}}, -y+1, z-{\script{1\over 2}}]; (iii) [-x+{\script{1\over 2}}, -y+1, z+{\script{1\over 2}}]; (iv) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z]; (v) x+1, y, z; (vi) [-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (vii) [-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}].

Data collection: CrysAlis CCD (Oxford Diffraction, 2007[Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]); cell refinement: CrysAlis RED (Oxford Diffraction, 2007[Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXD (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: DIAMOND (Brandenburg, 2001[Brandenburg, K. (2001). DIAMOND. Crystal Impact GbR, Bonn, Germany.]).

Supporting information


Comment top

The disease known as dieback of ash on European ash (Fraxinus excelsior) was first observed in Poland in 1995, but has spread rapidly over most of the European subcontinent (Przybyl, 2002). During studies of the secondary metabolite production of the fungus Hymenoscyphus pseudoalbidus, the pathogen responsible for dieback of ash (Queloz et al., 2011), a number of steroidal compounds have been isolated (Andersson et al., 2010; Andersson et al. 2013; Andersson et al. 2012). These compounds belong to a family of fungal steroids (Hanson, 1995), of which some have been shown to have interesting bioactivities (Cross et al. 1995; Smith et al. 2009; Andersson 2012).

The first reported compound of this family was viridin (Brian & McGowan, 1945), with its crystal structure published nearly 30 years later (Neidle et al., 1972). The absolute structures of a few other members have been reported through successful osmylation (Lang et al. 2009). Other members of the same family have also been characterized through other methods than crystallography, including wortmannin (Brian et al., 1957), demethoxyviridin and demethoxyviridiol (Aldridge et al., 1975), and virone and wortmannolone (Blight & Grove, 1986). The phytotoxin viridiol (Moffatt et al., 1969), which has also been suggested to be part of the pathogenicity of H. pseudoalbidus (Andersson et al. 2010), can be produced in Gliocladium virens from viridin (Jones & Hancock, 1987). The previously reported absolute configuration of these compounds are based on the evidence of their steroidal origin i. e. the configuration of the C10 carbon is based on lanosterol (Dewick, 2002; Harrison, 1990). Here, we present the crystal structure of viridiol (I) confirming the previously presented structure, both relative and absolute (MacMillan et al., 1972; Moffatt et al., 1969; Wipf & Kerekes, 2003) (Scheme 1, Fig. 1)

Compound (I) crystallizes in the orthorhombic space group P212121 (No. 19), with two crystallographically independent viridiol molecules with a total of eight in the unit cell. (Fig. 2) The nearly flat furanosteroid skeleton lies in the bc plane, with the A ring and its methoxy group bending away from the plane (Fig. 1). In the crystal, O—H···O and C—H···O interactions link the molecules (Table 1, Fig. 3).

Related literature top

For background to fungal metabolites, see: Brian & McGowan (1945); Moffatt et al. (1969); Jones & Hancock (1987); Hanson (1995); Cross et al. (1995); Przybyl (2002); Smith et al. (2009); Andersson et al. (2010); Queloz et al. (2011); Andersson (2012); Andersson et al. (2012, 2013). For related structures, see: Neidle et al. (1972); Lang et al. (2009). For other characterization methods, see: Brian et al. (1957); Aldridge et al. (1975); Blight & Grove (1986). For background to the assignment of the absolute structure of the title compound, see: MacMillan et al. (1972); Harrison (1990); Dewick (2002); Wipf & Kerekes (2003); Flack & Bernardinelli (2000).

Experimental top

The viridiol containing fraction from a previous study (Andersson et al., 2013) was subjected to rotatory evaporation, which lead to crystal formation. The crystals, too small for crystallography, were harvested by filtration and dried (approx. 3 mg). The crystals were subsequently dissolved in 80 °C toluene (4 ml) in a 5 ml test tube. The solution was left at room temperature and the toluene was evaporated slowly by a gentle stream of nitrogen gas. Large enough crystals formed at the bottom of the test tube after stepwise precipitation of impurities on the inner test tube wall. A colourless block was mounted on a glass capillary and a data set was measured under cold conditions (93 K).

Refinement top

After initial integration, the furanosteroid backbone was found through refinements using SHELXD. After additional cycles in SHELXL, the remaining atoms were found. No restraints were applied to the carbon skeleton. All non-H atoms were refined anisotropically. Hydrogen atoms on carbons were refined as riding on their respective carbon, while the two hydroxy hydrogen were fully refined. In the absence of any significant anomalous scattering, the Flack parameter was indeterminate (Flack & Bernardinelli, 2000). Hence, the Friedel equivalents were merged prior to the final refinements, and the absolute structure was set by reference to the known chirality of the pathway for the previously reported precursor lanosterol (Dewick, 2002; Harrison, 1990) (Fig. 4).

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXD (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXL (Sheldrick, 2008); software used to prepare material for publication: DIAMOND (Brandenburg, 2001).

Figures top
[Figure 1] Fig. 1. Labelling of (I) follows the system used previously (Aldridge et al., 1975). H atoms on alkyl and aryl carbons have been removed for clarity. Displacement ellipoids are set at 50%.
[Figure 2] Fig. 2. Unit cell packing of (I), viewed along the a axis.
[Figure 3] Fig. 3. One intramolecular and many intermolecular hydrogen bonds in the range 1.85–2.58 Å are present in (I), including both conventional (O–H···O) and non-conventional (C–H···O) ones.
[Figure 4] Fig. 4. ORTEP plot of (I).
1β,3β-Dihydroxy-2β-methoxyfuro[4',3',2':4,5,6]-18-norandrosta-8,11,13-triene-7,17-dione top
Crystal data top
C20H18O6F(000) = 1488
Mr = 354.34Dx = 1.522 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 5568 reflections
a = 6.8285 (2) Åθ = 2.9–32.3°
b = 20.1939 (6) ŵ = 0.11 mm1
c = 22.4344 (6) ÅT = 93 K
V = 3093.57 (15) Å3Block, colourless
Z = 80.3 × 0.25 × 0.2 mm
Data collection top
Oxford Diffraction XcaliburIII Sapphire-3 CCD
diffractometer
4874 independent reflections
Radiation source: fine-focus sealed tube3294 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.085
Detector resolution: 16.5467 pixels mm-1θmax = 29.6°, θmin = 3.1°
ω scans at different ϕh = 98
Absorption correction: multi-scan
(CrysAlis RED; Oxford Diffraction, 2007)
k = 2728
Tmin = 0.891, Tmax = 1.000l = 3127
26916 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.049H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.089 w = 1/[σ2(Fo2) + (0.0383P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.91(Δ/σ)max < 0.001
4874 reflectionsΔρmax = 0.33 e Å3
485 parametersΔρmin = 0.25 e Å3
0 restraintsAbsolute structure: syn
Primary atom site location: structure-invariant direct methods
Crystal data top
C20H18O6V = 3093.57 (15) Å3
Mr = 354.34Z = 8
Orthorhombic, P212121Mo Kα radiation
a = 6.8285 (2) ŵ = 0.11 mm1
b = 20.1939 (6) ÅT = 93 K
c = 22.4344 (6) Å0.3 × 0.25 × 0.2 mm
Data collection top
Oxford Diffraction XcaliburIII Sapphire-3 CCD
diffractometer
4874 independent reflections
Absorption correction: multi-scan
(CrysAlis RED; Oxford Diffraction, 2007)
3294 reflections with I > 2σ(I)
Tmin = 0.891, Tmax = 1.000Rint = 0.085
26916 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0490 restraints
wR(F2) = 0.089H atoms treated by a mixture of independent and constrained refinement
S = 0.91Δρmax = 0.33 e Å3
4874 reflectionsΔρmin = 0.25 e Å3
485 parametersAbsolute structure: syn
Special details top

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
C1A0.6537 (4)0.27709 (14)0.36272 (12)0.0138 (6)
H1A0.76960.26480.33780.017*
C2A0.7233 (4)0.33366 (13)0.40850 (12)0.0126 (6)
H2A0.85100.35060.39280.015*
C3A0.5943 (4)0.39445 (13)0.41746 (12)0.0133 (6)
H3A0.67280.42960.43790.016*
C4A0.5392 (4)0.41850 (13)0.35652 (12)0.0130 (6)
C5A0.5063 (4)0.37163 (12)0.31066 (11)0.0112 (5)
C6A0.4956 (5)0.40461 (12)0.25876 (11)0.0144 (6)
C7A0.4926 (4)0.37424 (13)0.20055 (11)0.0142 (6)
C8A0.4930 (5)0.29928 (12)0.20388 (11)0.0129 (6)
C9A0.4948 (4)0.26436 (12)0.25865 (11)0.0111 (6)
C10A0.4855 (5)0.29948 (12)0.31901 (11)0.0125 (6)
C11A0.4926 (5)0.19481 (13)0.25915 (11)0.0154 (6)
H11A0.49410.17210.29620.019*
C12A0.4883 (5)0.15934 (13)0.20748 (11)0.0142 (6)
H12A0.48690.11230.20820.017*
C13A0.4860 (5)0.19347 (13)0.15357 (11)0.0128 (6)
C14A0.4907 (5)0.26182 (13)0.15062 (11)0.0128 (6)
C15A0.4908 (5)0.28556 (13)0.08641 (11)0.0170 (6)
H15A0.61030.31150.07760.020*
H15B0.37440.31330.07810.020*
C16A0.4857 (5)0.22141 (13)0.04961 (11)0.0169 (6)
H16A0.36960.22090.02320.020*
H16B0.60480.21770.02470.020*
C17A0.4762 (4)0.16537 (14)0.09340 (11)0.0144 (6)
C18A0.2815 (4)0.28525 (15)0.34602 (12)0.0152 (6)
H18A0.27040.30730.38480.023*
H18B0.26500.23740.35120.023*
H18C0.17980.30210.31920.023*
O19A0.5889 (3)0.21883 (10)0.39170 (9)0.0183 (5)
H19A0.690 (5)0.1979 (16)0.4026 (14)0.027*
O20A0.4303 (3)0.37778 (10)0.45422 (9)0.0175 (5)
H20A0.360 (5)0.4134 (16)0.4665 (13)0.026*
C21A0.5428 (4)0.47768 (14)0.32940 (12)0.0169 (7)
H21A0.56200.51850.34950.020*
O22A0.5152 (3)0.47204 (8)0.26879 (7)0.0163 (4)
O23A0.4968 (3)0.40411 (9)0.15318 (8)0.0202 (5)
O24A0.4658 (3)0.10611 (9)0.08101 (8)0.0197 (5)
O25A0.7644 (3)0.30680 (10)0.46491 (8)0.0155 (5)
C26A0.9470 (5)0.27292 (15)0.46869 (13)0.0198 (7)
H26A0.95990.24250.43490.030*
H26B0.95250.24780.50600.030*
H26C1.05420.30520.46780.030*
C1B0.1585 (4)0.56087 (14)0.11712 (12)0.0138 (6)
H1B0.27730.57070.14160.017*
C2B0.2209 (4)0.50356 (13)0.07249 (11)0.0122 (6)
H2B0.34100.48260.08970.015*
C3B0.0753 (4)0.44728 (14)0.06042 (12)0.0142 (6)
H3B0.14510.41120.03850.017*
C4B0.0186 (5)0.42186 (13)0.12046 (12)0.0148 (6)
C5B0.0000 (5)0.46678 (12)0.16840 (11)0.0122 (6)
C6B0.0095 (5)0.43195 (12)0.21909 (12)0.0153 (6)
C7B0.0047 (5)0.45916 (13)0.27823 (12)0.0147 (6)
C8B0.0128 (5)0.53407 (12)0.27772 (11)0.0131 (6)
C9B0.0140 (4)0.57193 (13)0.22427 (11)0.0124 (6)
C10B0.0063 (5)0.54023 (12)0.16285 (11)0.0122 (6)
C11B0.0197 (4)0.64112 (12)0.22764 (11)0.0130 (6)
H11B0.02210.66610.19170.016*
C12B0.0220 (5)0.67419 (13)0.28128 (11)0.0142 (6)
H12B0.02440.72120.28270.017*
C13B0.0207 (4)0.63669 (13)0.33360 (11)0.0111 (6)
C14B0.0183 (4)0.56769 (12)0.33227 (11)0.0126 (6)
C15B0.0213 (5)0.53980 (13)0.39498 (11)0.0143 (6)
H15C0.13830.51160.40110.017*
H15D0.09740.51300.40270.017*
C16B0.0272 (5)0.60024 (13)0.43590 (11)0.0152 (6)
H16C0.08550.59980.46360.018*
H16D0.14960.60060.45960.018*
C17B0.0180 (5)0.66011 (13)0.39581 (11)0.0148 (6)
C18B0.2121 (5)0.55864 (15)0.13852 (13)0.0175 (7)
H18D0.23040.53860.09910.026*
H18E0.22310.60690.13530.026*
H18F0.31280.54200.16580.026*
O19B0.1100 (3)0.62125 (10)0.08747 (9)0.0187 (5)
H19B0.052 (5)0.6121 (16)0.0560 (14)0.028*
O20B0.0878 (3)0.46870 (10)0.02504 (9)0.0194 (5)
H20B0.090 (5)0.4507 (15)0.0072 (14)0.029*
C21B0.0133 (5)0.36090 (14)0.14567 (12)0.0180 (6)
H21B0.01990.32060.12400.022*
O22B0.0029 (3)0.36481 (8)0.20658 (8)0.0182 (4)
O23B0.0138 (4)0.42681 (9)0.32411 (8)0.0211 (5)
O24B0.0124 (4)0.71751 (9)0.41237 (8)0.0244 (5)
O25B0.2759 (3)0.53000 (9)0.01613 (8)0.0145 (4)
C26B0.4663 (4)0.55951 (14)0.01558 (12)0.0165 (6)
H26D0.47400.59340.04680.025*
H26E0.48990.58000.02330.025*
H26F0.56540.52540.02290.025*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C1A0.0182 (16)0.0109 (15)0.0122 (14)0.0002 (12)0.0016 (12)0.0007 (12)
C2A0.0151 (16)0.0110 (14)0.0118 (15)0.0000 (12)0.0030 (12)0.0008 (12)
C3A0.0185 (16)0.0079 (14)0.0136 (14)0.0002 (12)0.0016 (12)0.0013 (12)
C4A0.0125 (16)0.0121 (14)0.0145 (14)0.0004 (12)0.0001 (12)0.0001 (11)
C5A0.0091 (14)0.0125 (13)0.0119 (13)0.0005 (13)0.0025 (13)0.0004 (10)
C6A0.0152 (15)0.0095 (14)0.0185 (14)0.0027 (14)0.0001 (14)0.0001 (11)
C7A0.0112 (15)0.0141 (13)0.0174 (14)0.0001 (14)0.0007 (14)0.0025 (12)
C8A0.0134 (15)0.0120 (13)0.0134 (13)0.0012 (14)0.0038 (13)0.0007 (11)
C9A0.0083 (14)0.0108 (13)0.0141 (13)0.0001 (13)0.0005 (13)0.0004 (10)
C10A0.0162 (16)0.0113 (13)0.0101 (12)0.0001 (14)0.0004 (13)0.0007 (10)
C11A0.0211 (16)0.0144 (14)0.0108 (13)0.0001 (15)0.0002 (14)0.0033 (11)
C12A0.0188 (16)0.0085 (12)0.0152 (14)0.0021 (14)0.0013 (14)0.0011 (11)
C13A0.0117 (15)0.0142 (13)0.0125 (13)0.0026 (14)0.0023 (13)0.0013 (11)
C14A0.0109 (15)0.0159 (14)0.0116 (13)0.0009 (14)0.0004 (13)0.0017 (10)
C15A0.0234 (17)0.0141 (14)0.0134 (13)0.0011 (15)0.0019 (14)0.0036 (11)
C16A0.0231 (17)0.0176 (14)0.0099 (13)0.0016 (15)0.0023 (14)0.0009 (11)
C17A0.0124 (16)0.0169 (14)0.0139 (14)0.0008 (14)0.0010 (13)0.0039 (12)
C18A0.0186 (16)0.0125 (15)0.0145 (15)0.0011 (13)0.0036 (12)0.0005 (12)
O19A0.0266 (14)0.0097 (11)0.0186 (11)0.0012 (10)0.0061 (9)0.0043 (9)
O20A0.0188 (12)0.0145 (11)0.0191 (11)0.0039 (9)0.0067 (9)0.0023 (9)
C21A0.0189 (18)0.0146 (15)0.0172 (15)0.0015 (13)0.0044 (13)0.0010 (12)
O22A0.0256 (12)0.0077 (9)0.0156 (10)0.0006 (10)0.0014 (10)0.0008 (7)
O23A0.0269 (12)0.0153 (10)0.0185 (10)0.0001 (11)0.0040 (11)0.0042 (8)
O24A0.0285 (13)0.0172 (11)0.0134 (10)0.0004 (10)0.0014 (9)0.0024 (8)
O25A0.0172 (12)0.0160 (11)0.0133 (10)0.0024 (9)0.0013 (8)0.0035 (9)
C26A0.0192 (18)0.0183 (16)0.0220 (16)0.0018 (14)0.0027 (13)0.0008 (13)
C1B0.0179 (17)0.0129 (16)0.0106 (14)0.0027 (13)0.0007 (12)0.0002 (12)
C2B0.0188 (16)0.0107 (14)0.0070 (13)0.0024 (12)0.0005 (12)0.0002 (11)
C3B0.0170 (17)0.0102 (14)0.0153 (15)0.0035 (13)0.0002 (12)0.0018 (12)
C4B0.0114 (15)0.0133 (14)0.0196 (15)0.0031 (14)0.0018 (13)0.0041 (11)
C5B0.0114 (15)0.0102 (13)0.0151 (14)0.0002 (14)0.0001 (13)0.0042 (10)
C6B0.0190 (16)0.0067 (13)0.0202 (14)0.0009 (14)0.0039 (14)0.0019 (11)
C7B0.0137 (15)0.0125 (13)0.0178 (14)0.0023 (13)0.0022 (14)0.0019 (11)
C8B0.0148 (15)0.0104 (13)0.0142 (13)0.0035 (13)0.0013 (13)0.0000 (11)
C9B0.0123 (15)0.0126 (14)0.0124 (13)0.0020 (13)0.0000 (13)0.0003 (10)
C10B0.0155 (15)0.0082 (13)0.0131 (13)0.0033 (14)0.0008 (13)0.0012 (10)
C11B0.0161 (16)0.0105 (13)0.0125 (13)0.0002 (13)0.0015 (13)0.0032 (10)
C12B0.0181 (17)0.0073 (13)0.0173 (14)0.0008 (13)0.0001 (13)0.0024 (11)
C13B0.0078 (14)0.0156 (14)0.0101 (13)0.0014 (13)0.0008 (12)0.0015 (10)
C14B0.0090 (15)0.0132 (14)0.0157 (14)0.0013 (13)0.0007 (13)0.0045 (11)
C15B0.0186 (17)0.0111 (13)0.0132 (13)0.0009 (14)0.0009 (13)0.0024 (10)
C16B0.0173 (16)0.0174 (14)0.0109 (13)0.0006 (14)0.0021 (12)0.0025 (11)
C17B0.0142 (16)0.0133 (14)0.0170 (14)0.0006 (14)0.0030 (13)0.0029 (11)
C18B0.0209 (17)0.0149 (16)0.0167 (15)0.0024 (14)0.0062 (13)0.0018 (13)
O19B0.0324 (13)0.0112 (11)0.0125 (10)0.0024 (9)0.0019 (10)0.0015 (9)
O20B0.0196 (12)0.0227 (12)0.0160 (11)0.0050 (10)0.0058 (9)0.0068 (9)
C21B0.0187 (16)0.0165 (15)0.0187 (15)0.0018 (15)0.0013 (14)0.0054 (12)
O22B0.0256 (12)0.0097 (9)0.0195 (10)0.0004 (10)0.0039 (11)0.0013 (8)
O23B0.0325 (13)0.0138 (10)0.0169 (10)0.0022 (11)0.0044 (11)0.0042 (8)
O24B0.0435 (14)0.0147 (10)0.0151 (10)0.0009 (12)0.0042 (11)0.0013 (8)
O25B0.0178 (11)0.0138 (10)0.0118 (10)0.0004 (9)0.0003 (8)0.0019 (8)
C26B0.0149 (17)0.0177 (14)0.0169 (14)0.0017 (13)0.0008 (13)0.0007 (12)
Geometric parameters (Å, º) top
C1A—O19A1.415 (3)C1B—O19B1.428 (3)
C1A—C10A1.576 (4)C1B—C10B1.579 (4)
C1A—C2A1.608 (4)C1B—C2B1.589 (4)
C1A—H1A1.0000C1B—H1B1.0000
C2A—O25A1.405 (3)C2B—O25B1.423 (3)
C2A—C3A1.524 (4)C2B—C3B1.534 (4)
C2A—H2A1.0000C2B—H2B1.0000
C3A—O20A1.431 (3)C3B—O20B1.434 (3)
C3A—C4A1.499 (4)C3B—C4B1.492 (4)
C3A—H3A1.0000C3B—H3B1.0000
C4A—C21A1.341 (4)C4B—C21B1.355 (4)
C4A—C5A1.416 (3)C4B—C5B1.413 (3)
C5A—C6A1.343 (3)C5B—C6B1.339 (3)
C5A—C10A1.476 (4)C5B—C10B1.489 (3)
C6A—O22A1.386 (3)C6B—O22B1.385 (3)
C6A—C7A1.443 (4)C6B—C7B1.439 (4)
C7A—O23A1.222 (3)C7B—O23B1.221 (3)
C7A—C8A1.516 (3)C7B—C8B1.514 (4)
C8A—C14A1.414 (3)C8B—C14B1.400 (4)
C8A—C9A1.417 (3)C8B—C9B1.422 (3)
C9A—C11A1.405 (4)C9B—C11B1.400 (3)
C9A—C10A1.530 (3)C9B—C10B1.526 (3)
C10A—C18A1.546 (4)C10B—C18B1.553 (4)
C11A—C12A1.363 (3)C11B—C12B1.377 (3)
C11A—H11A0.9500C11B—H11B0.9500
C12A—C13A1.392 (3)C12B—C13B1.397 (3)
C12A—H12A0.9500C12B—H12B0.9500
C13A—C14A1.382 (4)C13B—C14B1.394 (3)
C13A—C17A1.466 (4)C13B—C17B1.474 (4)
C14A—C15A1.518 (3)C14B—C15B1.515 (3)
C15A—C16A1.537 (3)C15B—C16B1.528 (4)
C15A—H15A0.9900C15B—H15C0.9900
C15A—H15B0.9900C15B—H15D0.9900
C16A—C17A1.500 (4)C16B—C17B1.508 (4)
C16A—H16A0.9900C16B—H16C0.9900
C16A—H16B0.9900C16B—H16D0.9900
C17A—O24A1.231 (3)C17B—O24B1.218 (3)
C18A—H18A0.9800C18B—H18D0.9800
C18A—H18B0.9800C18B—H18E0.9800
C18A—H18C0.9800C18B—H18F0.9800
O19A—H19A0.84 (3)O19B—H19B0.83 (3)
O20A—H20A0.91 (3)O20B—H20B0.81 (3)
C21A—O22A1.377 (3)C21B—O22B1.373 (3)
C21A—H21A0.9500C21B—H21B0.9500
O25A—C26A1.425 (4)O25B—C26B1.430 (3)
C26A—H26A0.9800C26B—H26D0.9800
C26A—H26B0.9800C26B—H26E0.9800
C26A—H26C0.9800C26B—H26F0.9800
O19A—C1A—C10A107.2 (2)O19B—C1B—C10B111.3 (2)
O19A—C1A—C2A112.9 (2)O19B—C1B—C2B113.0 (2)
C10A—C1A—C2A114.1 (2)C10B—C1B—C2B114.1 (2)
O19A—C1A—H1A107.4O19B—C1B—H1B105.9
C10A—C1A—H1A107.4C10B—C1B—H1B105.9
C2A—C1A—H1A107.4C2B—C1B—H1B105.9
O25A—C2A—C3A107.9 (2)O25B—C2B—C3B107.0 (2)
O25A—C2A—C1A111.1 (2)O25B—C2B—C1B110.9 (2)
C3A—C2A—C1A119.0 (2)C3B—C2B—C1B118.5 (2)
O25A—C2A—H2A106.0O25B—C2B—H2B106.6
C3A—C2A—H2A106.0C3B—C2B—H2B106.6
C1A—C2A—H2A106.0C1B—C2B—H2B106.6
O20A—C3A—C4A113.9 (2)O20B—C3B—C4B113.7 (2)
O20A—C3A—C2A109.8 (2)O20B—C3B—C2B112.2 (2)
C4A—C3A—C2A106.6 (2)C4B—C3B—C2B105.3 (2)
O20A—C3A—H3A108.8O20B—C3B—H3B108.5
C4A—C3A—H3A108.8C4B—C3B—H3B108.5
C2A—C3A—H3A108.8C2B—C3B—H3B108.5
C21A—C4A—C5A105.6 (2)C21B—C4B—C5B105.3 (2)
C21A—C4A—C3A134.3 (3)C21B—C4B—C3B134.1 (3)
C5A—C4A—C3A119.1 (2)C5B—C4B—C3B119.3 (2)
C6A—C5A—C4A107.9 (2)C6B—C5B—C4B108.3 (2)
C6A—C5A—C10A126.5 (2)C6B—C5B—C10B126.4 (2)
C4A—C5A—C10A125.7 (2)C4B—C5B—C10B125.3 (2)
C5A—C6A—O22A109.9 (2)C5B—C6B—O22B109.9 (2)
C5A—C6A—C7A125.1 (2)C5B—C6B—C7B125.4 (2)
O22A—C6A—C7A124.4 (2)O22B—C6B—C7B123.9 (2)
O23A—C7A—C6A125.2 (2)O23B—C7B—C6B125.2 (2)
O23A—C7A—C8A122.4 (2)O23B—C7B—C8B122.6 (2)
C6A—C7A—C8A112.3 (2)C6B—C7B—C8B112.1 (2)
C14A—C8A—C9A117.8 (2)C14B—C8B—C9B118.4 (2)
C14A—C8A—C7A119.5 (2)C14B—C8B—C7B118.6 (2)
C9A—C8A—C7A122.7 (2)C9B—C8B—C7B123.0 (2)
C11A—C9A—C8A120.3 (2)C11B—C9B—C8B119.4 (2)
C11A—C9A—C10A117.1 (2)C11B—C9B—C10B118.0 (2)
C8A—C9A—C10A122.5 (2)C8B—C9B—C10B122.4 (2)
C5A—C10A—C9A110.0 (2)C5B—C10B—C9B109.9 (2)
C5A—C10A—C18A108.7 (2)C5B—C10B—C18B107.1 (2)
C9A—C10A—C18A107.3 (2)C9B—C10B—C18B107.4 (2)
C5A—C10A—C1A107.0 (2)C5B—C10B—C1B107.3 (2)
C9A—C10A—C1A112.8 (2)C9B—C10B—C1B114.3 (2)
C18A—C10A—C1A111.1 (2)C18B—C10B—C1B110.7 (2)
C12A—C11A—C9A121.3 (2)C12B—C11B—C9B122.1 (2)
C12A—C11A—H11A119.4C12B—C11B—H11B118.9
C9A—C11A—H11A119.4C9B—C11B—H11B118.9
C11A—C12A—C13A118.6 (2)C11B—C12B—C13B118.1 (2)
C11A—C12A—H12A120.7C11B—C12B—H12B120.9
C13A—C12A—H12A120.7C13B—C12B—H12B120.9
C14A—C13A—C12A122.4 (2)C14B—C13B—C12B121.6 (2)
C14A—C13A—C17A110.1 (2)C14B—C13B—C17B109.9 (2)
C12A—C13A—C17A127.5 (2)C12B—C13B—C17B128.4 (2)
C13A—C14A—C8A119.6 (2)C13B—C14B—C8B120.2 (2)
C13A—C14A—C15A111.1 (2)C13B—C14B—C15B110.6 (2)
C8A—C14A—C15A129.3 (2)C8B—C14B—C15B129.2 (2)
C14A—C15A—C16A104.1 (2)C14B—C15B—C16B105.2 (2)
C14A—C15A—H15A110.9C14B—C15B—H15C110.7
C16A—C15A—H15A110.9C16B—C15B—H15C110.7
C14A—C15A—H15B110.9C14B—C15B—H15D110.7
C16A—C15A—H15B110.9C16B—C15B—H15D110.7
H15A—C15A—H15B109.0H15C—C15B—H15D108.8
C17A—C16A—C15A106.6 (2)C17B—C16B—C15B106.3 (2)
C17A—C16A—H16A110.4C17B—C16B—H16C110.5
C15A—C16A—H16A110.4C15B—C16B—H16C110.5
C17A—C16A—H16B110.4C17B—C16B—H16D110.5
C15A—C16A—H16B110.4C15B—C16B—H16D110.5
H16A—C16A—H16B108.6H16C—C16B—H16D108.7
O24A—C17A—C13A125.9 (2)O24B—C17B—C13B126.5 (2)
O24A—C17A—C16A126.0 (2)O24B—C17B—C16B125.6 (2)
C13A—C17A—C16A108.0 (2)C13B—C17B—C16B107.9 (2)
C10A—C18A—H18A109.5C10B—C18B—H18D109.5
C10A—C18A—H18B109.5C10B—C18B—H18E109.5
H18A—C18A—H18B109.5H18D—C18B—H18E109.5
C10A—C18A—H18C109.5C10B—C18B—H18F109.5
H18A—C18A—H18C109.5H18D—C18B—H18F109.5
H18B—C18A—H18C109.5H18E—C18B—H18F109.5
C1A—O19A—H19A107 (2)C1B—O19B—H19B108 (2)
C3A—O20A—H20A114 (2)C3B—O20B—H20B112 (2)
C4A—C21A—O22A111.8 (2)C4B—C21B—O22B111.4 (2)
C4A—C21A—H21A124.1C4B—C21B—H21B124.3
O22A—C21A—H21A124.1O22B—C21B—H21B124.3
C21A—O22A—C6A104.8 (2)C21B—O22B—C6B105.11 (19)
C2A—O25A—C26A114.4 (2)C2B—O25B—C26B113.8 (2)
O25A—C26A—H26A109.5O25B—C26B—H26D109.5
O25A—C26A—H26B109.5O25B—C26B—H26E109.5
H26A—C26A—H26B109.5H26D—C26B—H26E109.5
O25A—C26A—H26C109.5O25B—C26B—H26F109.5
H26A—C26A—H26C109.5H26D—C26B—H26F109.5
H26B—C26A—H26C109.5H26E—C26B—H26F109.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O19A—H19A···O19Bi0.85 (3)2.08 (3)2.886 (3)160 (3)
O19B—H19B···O20Aii0.83 (3)2.30 (3)3.002 (3)143 (3)
O20A—H20A···O25Biii0.91 (3)1.85 (3)2.717 (3)160 (3)
O20B—H20B···O24Aiv0.81 (3)2.05 (3)2.842 (3)166 (3)
C2A—H2A···O23Bv1.002.453.325 (3)146
C2B—H2B···O23A1.002.383.295 (3)151
C11A—H11A···O19A0.952.433.084 (3)126
C11B—H11B···O19B0.952.583.230 (3)126
C18A—H18A···O20A0.982.383.227 (3)145
C18B—H18D···O20B0.982.393.241 (4)145
C21A—H21A···O24Avi0.952.373.282 (3)162
C21B—H21B···O24Bvii0.952.253.180 (3)167
Symmetry codes: (i) x+1, y1/2, z+1/2; (ii) x+1/2, y+1, z1/2; (iii) x+1/2, y+1, z+1/2; (iv) x1/2, y+1/2, z; (v) x+1, y, z; (vi) x+1, y+1/2, z+1/2; (vii) x, y1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC20H18O6
Mr354.34
Crystal system, space groupOrthorhombic, P212121
Temperature (K)93
a, b, c (Å)6.8285 (2), 20.1939 (6), 22.4344 (6)
V3)3093.57 (15)
Z8
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.3 × 0.25 × 0.2
Data collection
DiffractometerOxford Diffraction XcaliburIII Sapphire-3 CCD
diffractometer
Absorption correctionMulti-scan
(CrysAlis RED; Oxford Diffraction, 2007)
Tmin, Tmax0.891, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
26916, 4874, 3294
Rint0.085
(sin θ/λ)max1)0.694
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.089, 0.91
No. of reflections4874
No. of parameters485
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.33, 0.25
Absolute structureSyn

Computer programs: CrysAlis CCD (Oxford Diffraction, 2007), CrysAlis RED (Oxford Diffraction, 2007), SHELXD (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXL (Sheldrick, 2008), DIAMOND (Brandenburg, 2001).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O19A—H19A···O19Bi0.85 (3)2.08 (3)2.886 (3)160 (3)
O19B—H19B···O20Aii0.83 (3)2.30 (3)3.002 (3)143 (3)
O20A—H20A···O25Biii0.91 (3)1.85 (3)2.717 (3)160 (3)
O20B—H20B···O24Aiv0.81 (3)2.05 (3)2.842 (3)166 (3)
C2A—H2A···O23Bv1.002.453.325 (3)146
C2B—H2B···O23A1.002.383.295 (3)151
C11A—H11A···O19A0.952.433.084 (3)126
C11B—H11B···O19B0.952.583.230 (3)126
C18A—H18A···O20A0.982.383.227 (3)145
C18B—H18D···O20B0.982.393.241 (4)145
C21A—H21A···O24Avi0.952.373.282 (3)162
C21B—H21B···O24Bvii0.952.253.180 (3)167
Symmetry codes: (i) x+1, y1/2, z+1/2; (ii) x+1/2, y+1, z1/2; (iii) x+1/2, y+1, z+1/2; (iv) x1/2, y+1/2, z; (v) x+1, y, z; (vi) x+1, y+1/2, z+1/2; (vii) x, y1/2, z+1/2.
 

Acknowledgements

We are grateful to Dr Lars Eriksson for skillful technical assistance and fruitful discussions. The isolate Ö3 from which the viridiol was obtained was from a study which was, in part, supported by the Swedish research council FORMAS grant No. 2010–1344.

References

First citationAldridge, D. C., Turner, W. B., Geddes, A. J. & Sheldrick, B. (1975). J. Chem. Soc. Perkin Trans. 1, pp. 943–945.  CrossRef Web of Science
First citationAndersson, P. F. (2012). PhD thesis, Swedish University of Agricultural Sciences, Uppsala, Sweden. Available at http://pub.epsilon.slu.se/8996 .
First citationAndersson, P. F., Bengtsson, S., Cleary, M. R., Stenlid, J. & Broberg, A. (2013). Phytochemistry, 86, 195–200.  Web of Science CrossRef CAS PubMed
First citationAndersson, P. F., Bengtsson, S., Stenlid, J. & Broberg, A. (2012). Molecules, 17, 7769–7781.  Web of Science CrossRef CAS PubMed
First citationAndersson, P. F., Johansson, S. B. K., Stenlid, J. & Broberg, A. (2010). For. Pathol. 40, 43–46.  Web of Science CrossRef
First citationBlight, M. M. & Grove, J. F. (1986). J. Chem. Soc. Perkin Trans. 1, pp. 1317–1322.  CrossRef Web of Science
First citationBrandenburg, K. (2001). DIAMOND. Crystal Impact GbR, Bonn, Germany.
First citationBrian, P. W., Curtis, P. J., Hemming, H. G. & Norris, G. L. F. (1957). Trans. Br. Mycol. Soc. 40, 365–368.  CrossRef CAS
First citationBrian, P. W. & McGowan, J. C. (1945). Nature, 156, 144–145.  CrossRef CAS Web of Science
First citationCross, M. J., Stewart, A., Hodgkin, M. N., Kerr, D. J. & Wakelam, M. J. O. (1995). J. Biol. Chem. 270, 25352–25355.  CrossRef CAS PubMed Web of Science
First citationDewick, P. M. (2002). Nat. Prod. Rep. 19, 181–222.  Web of Science CrossRef PubMed CAS
First citationFlack, H. D. & Bernardinelli, G. (2000). J. Appl. Cryst. 33, 1143–1148.  Web of Science CrossRef CAS IUCr Journals
First citationHanson, J. R. (1995). Nat. Prod. Rep. 12, 381–384.  CrossRef CAS PubMed Web of Science
First citationHarrison, D. M. (1990). Nat. Prod. Rep. 7, 459–484.  CrossRef CAS PubMed Web of Science
First citationJones, R. W. & Hancock, J. G. (1987). Can. J. Microbiol. 33, 963–966.  CrossRef CAS PubMed
First citationLang, Y., Souza, F. E. S., Xu, X., Taylor, N. J., Assoud, A. & Rodrigo, R. (2009). J. Org. Chem. 74, 5429–5439.  Web of Science CSD CrossRef PubMed CAS
First citationMacMillan, J., Simpson, T. J., Vanstone, A. E. & Yeboah, S. K. (1972). J. Chem. Soc. Perkin Trans. 1, pp. 2892–2898.  CrossRef Web of Science
First citationMoffatt, J. S., Bu'Lock, J. D. & Yuen, T. H. (1969). J. Chem. Soc. D, p. 839a.
First citationNeidle, S., Rogers, D. & Hursthouse, M. B. (1972). J. Chem. Soc. Perkin Trans. 2, pp. 760–766.  CrossRef
First citationOxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.
First citationPrzybyl, K. (2002). For. Pathol. 32, 387–394.  Web of Science CrossRef
First citationQueloz, V., Grunig, C. R., Berndt, R., Kowalski, T., Sieber, T. N. & Holdenrieder, O. (2011). For. Pathol. 41, 133–142.  Web of Science CrossRef
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationSmith, A., Blois, J., Yuan, H., Aikawa, E., Ellson, C., Figueiredo, J. L., Weissleder, R., Kohler, R., Yaffe, M. B., Cantley, L. C. & Josephson, L. (2009). Mol. Cancer Ther. 8, 1666–1675.  Web of Science CrossRef PubMed CAS
First citationWipf, P. & Kerekes, A. D. (2003). J. Nat. Prod. 66, 716–718.  Web of Science CrossRef PubMed CAS

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 4| April 2013| Pages o467-o468
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds