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Acta Crystallogr Sect E Struct Rep Online. 2010 January 1; 66(Pt 1): o210.
Published online 2009 December 19. doi:  10.1107/S1600536809054178
PMCID: PMC2980171

Dihalogenated trichodermin (4β-acet­oxy-9,10-dibromo-12,13-epoxy­tri­chothec)

Abstract

In the title dihalogenated trichodermin mol­ecule, C17H24Br2O4 (systematic name: 9,10-dibromo-12,13-epoxy­trichothec-9-en-4β-yl acetate), the five-membered ring displays an envelope conformation, whereas the two six-membered rings show the same conformation, viz. chair. As for the seven-membered ring, the dihedral angle between the mean planes formed by the four C atoms of the envelope unit and the three C and one O atoms of the six-membered chair is 69.08 (4)°; these two mean planes are nearly perpendicular to the ep­oxy ring with angles of 87.53 (4) and 88.67 (4)°, respectively.

Related literature

For the fungicidal activity of trichodermin, see: Zhang et al. (2007 [triangle]). Trichodermin is a member of the 4β-ace­oxy-12,13-epoxy­trichothecene family, see: Nielsen et al. (2005 [triangle]). For the structure of trichodermin, see: Chen et al. (2008 [triangle]) and for the structure of a trichodermin derivative, see: Cheng et al. (2009 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-0o210-scheme1.jpg

Experimental

Crystal data

  • C17H24Br2O4
  • M r = 452.18
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-0o210-efi1.jpg
  • a = 10.0120 (4) Å
  • b = 8.3397 (4) Å
  • c = 11.1235 (6) Å
  • β = 106.6220 (10)°
  • V = 889.97 (7) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 4.57 mm−1
  • T = 296 K
  • 0.26 × 0.20 × 0.10 mm

Data collection

  • Rigaku R-AXIS RAPID diffractometer
  • Absorption correction: multi-scan (ABSCOR: Higashi, 1995 [triangle]) T min = 0.323, T max = 0.633
  • 8698 measured reflections
  • 3667 independent reflections
  • 2752 reflections with I > 2σ(I)
  • R int = 0.032

Refinement

  • R[F 2 > 2σ(F 2)] = 0.032
  • wR(F 2) = 0.095
  • S = 1.00
  • 3667 reflections
  • 213 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 0.67 e Å−3
  • Δρmin = −0.65 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1506 Friedel pairs
  • Flack parameter: 0.000 (15)

Data collection: PROCESS-AUTO (Rigaku, 2006 [triangle]); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku, 2007 [triangle]); 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]) and PLATON (Spek, 2009 [triangle]).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809054178/si2228sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809054178/si2228Isup2.hkl

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

Acknowledgments

The work was supported by the National Natural Science Foundation of China (No. 30700532) and the Science and Technology Project of Zhejiang Province (No. 2009 C21014). The authors are grateful to Professor Jianming Gu for the crystal structure analysis.

supplementary crystallographic information

Comment

The endophytic fungi Trichoderma taxi sp. nov. from Taxus mairei S.Y.Hu can produce a compound with fungicidal activity – Trichodermin (Zhang et al., 2007), which is a member of the 4β-aceoxy-12,13-epoxytrichothecene family (Nielsen et al., 2005). Bioassays showed Trichodermin strongly inhibited Rhizoctonia solani and Botrytis cinere. In order to find the relationship between the double bond of C position and biological activities, we designed to take the halogenation reaction, thus, the title compound had been synthesized. Its molecular structure is shown in Fig. 1. In the molecule, the five membered ring displays an envelope conformation with atom C12 at the flap position 0.694 (5) Å out of the mean plane formed by C2,C3,C4,C5. The pyranyl ring displays a chair conformation with the deviations of C11 and C12 being -0.578 (5) and 0.843 (5) Å, respectively. As well as cyclopentyl ring, with C7 and C10 at the flap positions deviating by 0.685 (5) and -0.464 (5) Å, respectively. And it is interesting that the ring change to the typical chair conformation after the double bond was being displaced by Br atoms, comparing with the structure of Trichodermin (Chen et al., 2008) and Trichodermol (4α-hydroxy- 12,13-epoxytrichothec-9-ene) (Cheng et al., 2009). As for the seven-membered ring, the dihedral angle between the mean planes formed by C2,C3,C4,C5 and C2,C5,C6,O1 is 69.08 (4) °, which are nearly perpendicular to the epoxy ring with angles of 87.53 (4) and 88.67 (4) °, respectively.

Experimental

In a flask, Br2(219 mg, 13.7 mmol, 2 equal) with 5 ml dichloromethane was added dropwise into a solution of Trichodermin (200 mg, 6.84 mmol, 1 equal), pyridine (108 mg, 13.7 mmol, 2 equal) and dichloromethane(15 ml). After stirring for 3 h at room temperature. The solution was washed with 1 N HCl, sat.NaHCO3 and dried over anhydrous Na2SO4. The solvent was evaporated in vacuo to afford the crude product, which was purified by column chromatography to afford the tittle compound (271 mg, 88%) as a white solid. The solid was filtrated and recrystallized with 95% ethanol to colourless blocks. The 1H NMR, ESI-MS data testified the title compound's structure. ESI-MS: 475.2 (M+Na)+ (100%); 1H-NMR (500 MHz, CDCl3): 5.57 (1H, m, H– 4), 4.62 (1H, s, H-10), 4.03 (1H, s, H-11), 3.87 (1H, d, J=5.0 Hz, H-2), 3.21 (1H, d, J=4.0 Hz, H-13), 2.94 (1H, d, J=4.0 Hz, H-13), 2.49–2.45 (1H, m, H-3), 2.42–2.36 (1H, m, H-8), 2.08 (3H, s, H-16), 2.06 (3H, s, H-18),2.01–1.98 (1H, m, H-3), 1.97–1.93 (1H, m, H-8), 1.92–1.88 (1H, m, H-7), 1.46–1.42 (1H, m, H-7), 1.38 (3H, s, H-14), 0.71 (3H, s, H-15).

Refinement

The H atoms were geometrically placed (C–H = 0.93–0.98 Å) and refined as riding with Uiso(H) = 1.2Ueq(C) or 1.5Ueq (methyl C). The absolute structure has been determined by using Flack's x parameter refinement (Flack, 1983) and 1506 Friedel related pairs of reflections. The PLATON (Spek, 2009) structure validation programme was applied and indicated eight C atoms with chiralities R (C2), R (C4), S (C5), R (C6), R (C9), R (C10), S (C11), S (C12) for the title molecule.

Figures

Fig. 1.
The molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 40% probability level.

Crystal data

C17H24Br2O4F(000) = 456
Mr = 452.18Dx = 1.687 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 6808 reflections
a = 10.0120 (4) Åθ = 3.1–27.4°
b = 8.3397 (4) ŵ = 4.57 mm1
c = 11.1235 (6) ÅT = 296 K
β = 106.622 (1)°Chunk, colorless
V = 889.97 (7) Å30.26 × 0.20 × 0.10 mm
Z = 2

Data collection

Rigaku R-AXIS RAPID diffractometer3667 independent reflections
Radiation source: rolling anode2752 reflections with I > 2σ(I)
graphiteRint = 0.032
Detector resolution: 10.00 pixels mm-1θmax = 27.4°, θmin = 3.1°
ω scansh = −12→12
Absorption correction: multi-scan (ABSCOR: Higashi, 1995)k = −10→10
Tmin = 0.323, Tmax = 0.633l = −14→14
8698 measured reflections

Refinement

Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.032w = 1/[σ2(Fo2) + (0.0003P)2 + 1.980P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.095(Δ/σ)max < 0.001
S = 1.00Δρmax = 0.67 e Å3
3667 reflectionsΔρmin = −0.65 e Å3
213 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.0189 (8)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1506 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: 0.000 (15)

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
Br20.88801 (4)0.21090 (8)0.71835 (5)0.06304 (15)
Br10.75860 (5)−0.28303 (7)0.84118 (5)0.05950 (14)
O20.2048 (3)−0.0632 (4)0.6936 (3)0.0520 (9)
O10.5492 (3)−0.0758 (3)0.6377 (3)0.0377 (7)
O30.2174 (3)0.2951 (4)0.5751 (3)0.0459 (9)
C110.6197 (4)0.0702 (5)0.6879 (5)0.0376 (10)
H110.60710.14710.61890.045*
O40.3167 (4)0.5380 (4)0.6153 (5)0.0713 (13)
C70.6122 (5)0.0479 (6)0.9123 (4)0.0408 (11)
H7A0.58260.10110.97790.049*
H7B0.5681−0.05670.89860.049*
C60.5623 (4)0.1472 (5)0.7900 (4)0.0353 (10)
C120.3494 (4)−0.0260 (5)0.7073 (4)0.0378 (10)
C20.3997 (4)−0.0627 (5)0.5960 (4)0.0351 (10)
H20.3575−0.16190.55490.042*
C50.3968 (4)0.1468 (5)0.7378 (4)0.0344 (9)
C130.3133 (5)−0.1439 (7)0.7910 (5)0.0545 (14)
H13A0.3312−0.25610.77860.065*
H13B0.3253−0.11290.87750.065*
C150.6110 (5)0.3216 (6)0.8173 (5)0.0486 (14)
H15A0.71070.32430.84970.073*
H15B0.57020.36640.87810.073*
H15C0.58250.38310.74130.073*
C80.7705 (5)0.0260 (6)0.9561 (4)0.0430 (12)
H8A0.81410.13030.97550.052*
H8B0.7950−0.03671.03280.052*
C170.2139 (5)0.4560 (6)0.5912 (5)0.0469 (12)
C100.7743 (5)0.0191 (6)0.7299 (5)0.0419 (11)
H100.7879−0.06000.66930.050*
C180.0687 (6)0.5157 (7)0.5733 (6)0.0670 (17)
H18A0.03350.47430.63880.100*
H18B0.01030.48040.49340.100*
H18C0.06920.63070.57620.100*
C40.3545 (4)0.2220 (7)0.6039 (4)0.0385 (9)
H40.42400.30110.59630.046*
C140.3263 (4)0.2247 (8)0.8282 (4)0.0471 (10)
H14A0.22750.20700.79870.071*
H14B0.34480.33780.83270.071*
H14C0.36230.17810.91000.071*
C90.8282 (5)−0.0555 (6)0.8612 (5)0.0431 (12)
C30.3483 (5)0.0813 (5)0.5121 (4)0.0401 (11)
H3A0.25380.06440.45960.048*
H3B0.40800.10180.45880.048*
C160.9878 (5)−0.0734 (8)0.9074 (6)0.0654 (17)
H16A1.02990.03070.92400.098*
H16B1.0199−0.12600.84410.098*
H16C1.0130−0.13610.98290.098*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Br20.0445 (2)0.0665 (3)0.0795 (3)−0.0133 (4)0.0199 (2)0.0144 (4)
Br10.0729 (3)0.0375 (2)0.0607 (3)0.0006 (4)0.0071 (2)0.0039 (3)
O20.0365 (16)0.058 (2)0.060 (2)−0.0100 (17)0.0112 (15)0.0042 (18)
O10.0380 (15)0.0318 (16)0.0433 (17)−0.0010 (14)0.0116 (12)−0.0068 (13)
O30.0347 (16)0.0360 (17)0.061 (2)0.0020 (14)0.0032 (15)0.0043 (15)
C110.032 (2)0.030 (2)0.049 (3)−0.0038 (19)0.0086 (19)0.0006 (19)
O40.058 (2)0.036 (2)0.118 (4)−0.0057 (19)0.021 (2)−0.010 (2)
C70.038 (2)0.047 (3)0.036 (2)−0.006 (2)0.0077 (18)0.0024 (19)
C60.036 (2)0.031 (2)0.038 (2)−0.0035 (18)0.0074 (17)−0.0069 (18)
C120.0303 (19)0.031 (2)0.049 (3)−0.0030 (19)0.0062 (18)0.0009 (19)
C20.036 (2)0.034 (2)0.034 (2)−0.007 (2)0.0081 (17)−0.0089 (18)
C50.0346 (19)0.030 (2)0.038 (2)−0.0037 (18)0.0105 (17)0.0000 (17)
C130.056 (3)0.047 (3)0.054 (3)−0.014 (3)0.006 (2)0.007 (2)
C150.048 (3)0.033 (2)0.062 (3)−0.005 (2)0.010 (2)−0.006 (2)
C80.040 (2)0.043 (3)0.041 (3)−0.005 (2)0.0032 (19)0.000 (2)
C170.045 (3)0.034 (2)0.060 (3)0.003 (2)0.014 (2)0.004 (2)
C100.037 (2)0.038 (2)0.052 (3)−0.004 (2)0.016 (2)0.005 (2)
C180.052 (3)0.053 (3)0.097 (5)0.014 (3)0.024 (3)0.012 (3)
C40.0332 (17)0.033 (2)0.047 (2)−0.003 (3)0.0073 (15)0.001 (3)
C140.0443 (19)0.052 (3)0.049 (2)0.001 (3)0.0197 (17)−0.012 (3)
C90.032 (2)0.042 (3)0.049 (3)0.000 (2)0.0023 (19)−0.001 (2)
C30.046 (2)0.043 (3)0.030 (2)−0.001 (2)0.0093 (19)−0.0010 (18)
C160.040 (3)0.075 (4)0.075 (4)0.008 (3)0.005 (3)0.005 (3)

Geometric parameters (Å, °)

Br2—C101.989 (5)C13—H13A0.9700
Br1—C92.012 (5)C13—H13B0.9700
O2—C121.445 (5)C15—H15A0.9600
O2—C131.461 (6)C15—H15B0.9600
O1—C111.438 (5)C15—H15C0.9600
O1—C21.439 (5)C8—C91.503 (7)
O3—C171.355 (6)C8—H8A0.9700
O3—C41.451 (5)C8—H8B0.9700
C11—C101.544 (6)C17—C181.494 (7)
C11—C61.551 (7)C10—C91.536 (7)
C11—H110.9800C10—H100.9800
O4—C171.200 (6)C18—H18A0.9600
C7—C81.530 (6)C18—H18B0.9600
C7—C61.548 (6)C18—H18C0.9600
C7—H7A0.9700C4—C31.546 (7)
C7—H7B0.9700C4—H40.9800
C6—C151.536 (6)C14—H14A0.9600
C6—C51.592 (6)C14—H14B0.9600
C12—C131.469 (7)C14—H14C0.9600
C12—C21.496 (6)C9—C161.539 (6)
C12—C51.524 (6)C3—H3A0.9700
C2—C31.518 (6)C3—H3B0.9700
C2—H20.9800C16—H16A0.9600
C5—C141.529 (6)C16—H16B0.9600
C5—C41.558 (6)C16—H16C0.9600
C12—O2—C1360.7 (3)C9—C8—C7113.7 (4)
C11—O1—C2114.3 (3)C9—C8—H8A108.8
C17—O3—C4116.4 (4)C7—C8—H8A108.8
O1—C11—C10102.8 (3)C9—C8—H8B108.8
O1—C11—C6113.1 (3)C7—C8—H8B108.8
C10—C11—C6116.2 (4)H8A—C8—H8B107.7
O1—C11—H11108.1O4—C17—O3122.7 (4)
C10—C11—H11108.1O4—C17—C18125.4 (5)
C6—C11—H11108.1O3—C17—C18111.9 (4)
C8—C7—C6112.9 (4)C9—C10—C11116.7 (4)
C8—C7—H7A109.0C9—C10—Br2109.6 (3)
C6—C7—H7A109.0C11—C10—Br2107.5 (3)
C8—C7—H7B109.0C9—C10—H10107.6
C6—C7—H7B109.0C11—C10—H10107.6
H7A—C7—H7B107.8Br2—C10—H10107.6
C15—C6—C7109.1 (4)C17—C18—H18A109.5
C15—C6—C11112.0 (4)C17—C18—H18B109.5
C7—C6—C11109.2 (4)H18A—C18—H18B109.5
C15—C6—C5108.2 (3)C17—C18—H18C109.5
C7—C6—C5111.1 (4)H18A—C18—H18C109.5
C11—C6—C5107.3 (3)H18B—C18—H18C109.5
O2—C12—C1360.2 (3)O3—C4—C3108.5 (3)
O2—C12—C2115.7 (4)O3—C4—C5111.2 (3)
C13—C12—C2126.1 (4)C3—C4—C5105.9 (4)
O2—C12—C5117.7 (4)O3—C4—H4110.4
C13—C12—C5127.5 (4)C3—C4—H4110.4
C2—C12—C5102.8 (4)C5—C4—H4110.4
O1—C2—C12108.3 (3)C5—C14—H14A109.5
O1—C2—C3113.3 (4)C5—C14—H14B109.5
C12—C2—C3102.2 (4)H14A—C14—H14B109.5
O1—C2—H2110.9C5—C14—H14C109.5
C12—C2—H2110.9H14A—C14—H14C109.5
C3—C2—H2110.9H14B—C14—H14C109.5
C12—C5—C14112.0 (4)C8—C9—C10112.6 (4)
C12—C5—C4100.7 (4)C8—C9—C16112.4 (4)
C14—C5—C4114.0 (4)C10—C9—C16113.9 (4)
C12—C5—C6108.0 (3)C8—C9—Br1108.3 (3)
C14—C5—C6112.8 (3)C10—C9—Br1105.1 (3)
C4—C5—C6108.5 (3)C16—C9—Br1103.8 (3)
O2—C13—C1259.1 (3)C2—C3—C4104.6 (4)
O2—C13—H13A117.9C2—C3—H3A110.8
C12—C13—H13A117.9C4—C3—H3A110.8
O2—C13—H13B117.9C2—C3—H3B110.8
C12—C13—H13B117.9C4—C3—H3B110.8
H13A—C13—H13B115.0H3A—C3—H3B108.9
C6—C15—H15A109.5C9—C16—H16A109.5
C6—C15—H15B109.5C9—C16—H16B109.5
H15A—C15—H15B109.5H16A—C16—H16B109.5
C6—C15—H15C109.5C9—C16—H16C109.5
H15A—C15—H15C109.5H16A—C16—H16C109.5
H15B—C15—H15C109.5H16B—C16—H16C109.5
C2—O1—C11—C10177.3 (4)C11—C6—C5—C14−178.3 (4)
C2—O1—C11—C651.2 (5)C15—C6—C5—C470.1 (5)
C8—C7—C6—C15−68.6 (5)C7—C6—C5—C4−170.1 (4)
C8—C7—C6—C1154.1 (5)C11—C6—C5—C4−50.9 (5)
C8—C7—C6—C5172.2 (4)C2—C12—C13—O2−101.5 (5)
O1—C11—C6—C15−165.1 (3)C5—C12—C13—O2103.6 (5)
C10—C11—C6—C1576.2 (5)C6—C7—C8—C9−58.6 (5)
O1—C11—C6—C773.9 (4)C4—O3—C17—O47.5 (7)
C10—C11—C6—C7−44.7 (5)C4—O3—C17—C18−173.4 (4)
O1—C11—C6—C5−46.6 (5)O1—C11—C10—C9−85.2 (5)
C10—C11—C6—C5−165.2 (4)C6—C11—C10—C938.9 (6)
C13—O2—C12—C2118.6 (5)O1—C11—C10—Br2151.3 (3)
C13—O2—C12—C5−119.5 (5)C6—C11—C10—Br2−84.6 (4)
C11—O1—C2—C12−63.9 (5)C17—O3—C4—C3−145.6 (4)
C11—O1—C2—C348.7 (5)C17—O3—C4—C598.4 (5)
O2—C12—C2—O1−159.2 (3)C12—C5—C4—O394.1 (4)
C13—C12—C2—O1−88.6 (5)C14—C5—C4—O3−26.0 (6)
C5—C12—C2—O171.2 (4)C6—C5—C4—O3−152.6 (4)
O2—C12—C2—C380.9 (4)C12—C5—C4—C3−23.5 (4)
C13—C12—C2—C3151.5 (4)C14—C5—C4—C3−143.6 (4)
C5—C12—C2—C3−48.7 (4)C6—C5—C4—C389.8 (4)
O2—C12—C5—C1437.6 (5)C7—C8—C9—C1048.9 (5)
C13—C12—C5—C14−34.7 (6)C7—C8—C9—C16179.1 (4)
C2—C12—C5—C14165.9 (3)C7—C8—C9—Br1−66.8 (4)
O2—C12—C5—C4−84.0 (4)C11—C10—C9—C8−39.4 (6)
C13—C12—C5—C4−156.2 (4)Br2—C10—C9—C883.1 (4)
C2—C12—C5—C444.3 (4)C11—C10—C9—C16−168.8 (4)
O2—C12—C5—C6162.4 (4)Br2—C10—C9—C16−46.3 (5)
C13—C12—C5—C690.1 (5)C11—C10—C9—Br178.3 (4)
C2—C12—C5—C6−69.3 (4)Br2—C10—C9—Br1−159.3 (2)
C15—C6—C5—C12178.4 (4)O1—C2—C3—C4−83.8 (4)
C7—C6—C5—C12−61.8 (5)C12—C2—C3—C432.6 (4)
C11—C6—C5—C1257.4 (4)O3—C4—C3—C2−124.6 (4)
C15—C6—C5—C14−57.3 (5)C5—C4—C3—C2−5.1 (4)
C7—C6—C5—C1462.5 (5)

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2228).

References

  • Chen, S.-Y., Zhang, C.-L., Chen, Y.-Z. & Lin, F.-C. (2008). Acta Cryst. E64, o702. [PMC free article] [PubMed]
  • Cheng, J.-L., Zhou, Y., Lin, F.-C., Zhao, J.-H. & Zhu, G.-N. (2009). Acta Cryst. E65, o2879. [PMC free article] [PubMed]
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Higashi, T. (1995). ABSCOR Rigaku Corporation, Tokyo, Japan.
  • Nielsen, K. F., Grafenhan, T., Zafari, D. & Thrane, U. (2005). J. Agric. Food Chem.53, 8190–8196. [PubMed]
  • Rigaku (2006). PROCESS-AUTO Rigaku Corporation, Tokyo, Japan.
  • Rigaku (2007). CrystalStructure Rigaku Corporation, Tokyo, Japan.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
  • Zhang, C., Liu, S., Lin, F., Kubicek, C. P. & Druzhinina, I. S. (2007). Microbiology Lett.270, 90–96. [PubMed]

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