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Acta Crystallogr Sect E Struct Rep Online. 2010 May 1; 66(Pt 5): o1132.
Published online 2010 April 21. doi:  10.1107/S1600536810012766
PMCID: PMC2979114

2-(4-Fluoro­phen­yl)-N-{4-[6-(4-fluoro­phen­yl)-2,3-dihydro­imidazo[2,1-b][1,3]thia­zol-5-yl]pyridin-2-yl}acetamide

Abstract

In the crystal structure of the title compound, C24H18F2N4OS, the imidazole system makes dihedral angles of 34.3 (1) and 43.9 (1)°, respectively, with the directly attached 4-fluoro­phenyl and pyridine rings. The crystal structure is stabilized by inter­molecular N—H(...)N hydrogen bonding and by an intra­molecular C—H(...)O hydrogen inter­action. The F atom of the 2-(4-fluoro­phen­yl) group is disordered over two positions with site-occupancy factors of 0.75 and 0.25.

Related literature

For related compounds and their biological relevance, see: Ziegler et al. (2009 [triangle]).

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Object name is e-66-o1132-scheme1.jpg

Experimental

Crystal data

  • C24H18F2N4OS
  • M r = 448.48
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o1132-efi1.jpg
  • a = 4.9179 (3) Å
  • b = 23.592 (1) Å
  • c = 18.4834 (9) Å
  • β = 91.523 (2)°
  • V = 2143.8 (2) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.19 mm−1
  • T = 173 K
  • 0.35 × 0.16 × 0.08 mm

Data collection

  • Bruker SMART APEXII diffractometer
  • 10277 measured reflections
  • 4846 independent reflections
  • 4129 reflections with I > 2σ(I)
  • R int = 0.028

Refinement

  • R[F 2 > 2σ(F 2)] = 0.038
  • wR(F 2) = 0.090
  • S = 1.03
  • 4846 reflections
  • 298 parameters
  • 2 restraints
  • H-atom parameters constrained
  • Δρmax = 0.23 e Å−3
  • Δρmin = −0.20 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 2197 Friedel pairs
  • Flack parameter: 0.07 (6)

Data collection: APEX2 (Bruker, 2006 [triangle]); cell refinement: SAINT (Bruker, 2006 [triangle]); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: PLATON (Spek, 2009 [triangle]); software used to prepare material for publication: PLATON.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810012766/im2189sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810012766/im2189Isup2.hkl

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

Acknowledgments

The authors would like to thank the Federal Ministry of Education and Research, Germany, Merckle GmbH, Ulm, Germany, and Fonds der Chemischen Industrie, Germany, for their generous support of this work.

supplementary crystallographic information

Comment

SKF86002 was an early lead compound of many imidazole based p38 MAP kinase inhibitors. A further improvement of these inhibitors was the modification of the pyridyl moiety by substitution with amines in C-2 position of the pyridine. This donor acceptor system can interact with hinge region/MET109 by bidentate hydrogen bonding. Additional interactions of the attached residues with the hydrophobic region II strongly increases potency of these compounds (Ziegler et al. 2009).

The imidazole system of the title compound 2-(4-fluorophenyl)-N-{4-[6-(4-fluorophenyl)-2,3-dihydroimidazo[2,1-b][1,3] thiazol-5-yl]-pyridin-2-yl}acetamide, C24H18F2N4OS, makes dihedral angles of 34.3 (1)° and 43.9 (1)° with the directly attached 4-fluorophenyl and the pyridine rings, respectively. The crystal structure is characterized by an intermolecular hydrogen bond N13—H13···N6 (2.02 Å). The molecular conformation is stabilized by an intramolecular C8—H8···O15 (2.24 Å) interaction. The flourine atom F1 is disordered over two positions with s.o.f 0.75:0.25.

Experimental

4-fluorphenylacetic acid (296 mg) was dissolved in 3 ml N-methylpyrrolidinone. After addition of 332 mg of carbonyldiimidazole the mixture was stirred for 1 h at room temperature. 200 mg 4-[6-(4-fluorophenyl)-2,3-dihydroimidazo[2,1-b][1,3]thiazol-5-yl]pyridin-2-amine was added and the reaction mixture was heated to 383 K for 19 h. The reaction mixture was quenched with a solution of concentrated sodium hydrogen carbonate and extracted with ethylacetate. The crude product was purified by flash chromatography (eluent: ethylacetate/hexane 2/1) to yield 155 mg (54%) of the title compound. Crystals suitable for X-ray analysis were obtained by slow crystallization from methanol at room temperature.

Refinement

Hydrogen atoms attached to carbons were placed at calculated positions with C—H = 0.95 Å (aromatic) or 0.98–0.99 Å (sp3 C-atom). All H atoms were refined in the riding-model approximation with isotropic displacement parameters (set at 1.2–1.5 times of the Ueq of the parent atom). The flourine F1 is disordered over two positions with s.o.f 0.75:0.25.

Figures

Fig. 1.
View of compound I. Displacement ellipsoids are drawn at the 50% probability level.

Crystal data

C24H18F2N4OSF(000) = 928
Mr = 448.48Dx = 1.390 Mg m3
Monoclinic, CcMo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2ycCell parameters from 3757 reflections
a = 4.9179 (3) Åθ = 2.2–26.4°
b = 23.592 (1) ŵ = 0.19 mm1
c = 18.4834 (9) ÅT = 173 K
β = 91.523 (2)°Plate, yellow
V = 2143.8 (2) Å30.35 × 0.16 × 0.08 mm
Z = 4

Data collection

Bruker SMART APEXII diffractometer4129 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.028
graphiteθmax = 28.2°, θmin = 1.7°
CCD scanh = −6→6
10277 measured reflectionsk = −30→28
4846 independent reflectionsl = −23→24

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.038H-atom parameters constrained
wR(F2) = 0.090w = 1/[σ2(Fo2) + (0.0433P)2 + 0.4891P] where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.001
4846 reflectionsΔρmax = 0.23 e Å3
298 parametersΔρmin = −0.20 e Å3
2 restraintsAbsolute structure: Flack (1983), 2197 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.07 (6)

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*/UeqOcc. (<1)
S10.82180 (11)0.16231 (2)−0.12400 (3)0.03583 (14)
F1A−0.3136 (9)−0.09848 (19)0.2022 (2)0.0837 (13)0.75
F1B−0.454 (3)−0.0837 (5)0.1902 (9)0.086 (4)0.25
F20.7391 (4)0.53748 (6)0.01213 (10)0.0609 (4)
C20.6645 (6)0.11864 (10)−0.05475 (12)0.0420 (6)
H2A0.46830.1135−0.06620.050*
H2B0.75170.0808−0.05250.050*
C30.7039 (6)0.14935 (9)0.01721 (11)0.0386 (6)
H3A0.55780.13940.05080.046*
H3B0.88210.13980.04020.046*
N3A0.6911 (4)0.20911 (7)−0.00241 (9)0.0294 (4)
C40.6770 (4)0.26014 (9)0.03519 (10)0.0277 (4)
C50.7275 (4)0.30126 (9)−0.01557 (10)0.0266 (4)
N60.7779 (4)0.27699 (7)−0.08266 (8)0.0302 (4)
C6A0.7576 (5)0.22229 (9)−0.07094 (10)0.0301 (4)
C70.6335 (4)0.26246 (8)0.11346 (10)0.0264 (4)
C80.4394 (4)0.22883 (9)0.14539 (10)0.0265 (4)
H80.32240.20530.11670.032*
C90.4195 (4)0.23019 (9)0.22064 (10)0.0251 (4)
N100.5728 (4)0.26393 (7)0.26344 (9)0.0289 (4)
C110.7533 (5)0.29740 (9)0.23135 (11)0.0313 (5)
H110.86010.32220.26100.038*
C120.7934 (4)0.29797 (9)0.15769 (10)0.0281 (4)
H120.92660.32200.13750.034*
N130.2423 (4)0.19595 (7)0.25989 (8)0.0269 (4)
H130.27200.20710.31020.032*
C140.0701 (4)0.15550 (9)0.23346 (11)0.0289 (4)
O150.0457 (4)0.14302 (8)0.16963 (8)0.0429 (4)
C16−0.0944 (5)0.12612 (10)0.29138 (11)0.0328 (5)
H16A0.01470.12470.33710.039*
H16B−0.26050.14850.30020.039*
C17−0.1743 (5)0.06690 (10)0.26956 (11)0.0339 (5)
C18−0.3773 (6)0.05731 (15)0.21804 (14)0.0533 (7)
H18−0.47800.08810.19790.064*
C19−0.4342 (8)0.00127 (19)0.19545 (17)0.0757 (12)
H19−0.5744−0.00610.16040.091*
C20−0.2856 (9)−0.04181 (15)0.22459 (18)0.0753 (12)
C21−0.0855 (9)−0.03416 (13)0.27436 (18)0.0693 (10)
H210.0149−0.06540.29340.083*
C22−0.0297 (6)0.02066 (11)0.29714 (14)0.0496 (7)
H220.11090.02680.33250.060*
C230.7289 (4)0.36344 (8)−0.00730 (10)0.0254 (4)
C240.5520 (5)0.39102 (9)0.03857 (11)0.0312 (5)
H240.42700.36950.06560.037*
C250.5560 (5)0.44968 (10)0.04538 (12)0.0379 (5)
H250.43610.46840.07700.045*
C260.7373 (5)0.47988 (9)0.00533 (12)0.0371 (5)
C270.9136 (5)0.45469 (10)−0.04073 (12)0.0383 (5)
H271.03590.4768−0.06800.046*
C280.9095 (5)0.39598 (9)−0.04675 (11)0.0320 (5)
H281.03160.3777−0.07820.038*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
S10.0618 (4)0.0249 (2)0.0210 (2)−0.0009 (3)0.0078 (2)−0.0022 (2)
F1A0.123 (4)0.061 (3)0.068 (2)−0.052 (2)0.019 (2)−0.0149 (17)
F1B0.110 (10)0.033 (5)0.113 (9)−0.036 (6)−0.005 (8)−0.016 (5)
F20.0845 (12)0.0243 (7)0.0745 (11)−0.0014 (8)0.0124 (9)−0.0004 (7)
C20.0714 (18)0.0268 (11)0.0284 (11)−0.0066 (11)0.0095 (11)0.0002 (9)
C30.0685 (17)0.0239 (11)0.0234 (10)−0.0072 (11)0.0050 (10)0.0033 (8)
N3A0.0477 (11)0.0230 (8)0.0177 (7)−0.0027 (8)0.0049 (7)0.0016 (6)
C40.0364 (11)0.0260 (10)0.0209 (9)−0.0048 (9)0.0041 (8)0.0005 (7)
C50.0344 (11)0.0265 (10)0.0191 (9)−0.0031 (9)0.0051 (8)−0.0002 (7)
N60.0458 (11)0.0254 (9)0.0196 (8)−0.0018 (8)0.0061 (7)0.0011 (7)
C6A0.0454 (12)0.0294 (11)0.0158 (8)−0.0029 (10)0.0046 (8)−0.0009 (8)
C70.0362 (11)0.0262 (11)0.0170 (9)0.0029 (9)0.0032 (8)0.0011 (7)
C80.0326 (11)0.0267 (10)0.0201 (9)−0.0020 (9)0.0025 (8)−0.0009 (7)
C90.0321 (11)0.0240 (10)0.0194 (9)0.0031 (8)0.0056 (8)0.0002 (7)
N100.0414 (11)0.0277 (9)0.0179 (7)−0.0015 (8)0.0048 (7)−0.0015 (6)
C110.0441 (13)0.0263 (10)0.0235 (9)−0.0045 (9)0.0013 (9)−0.0043 (8)
C120.0356 (11)0.0241 (10)0.0249 (9)−0.0017 (9)0.0046 (8)0.0001 (8)
N130.0374 (10)0.0265 (9)0.0172 (7)−0.0021 (8)0.0071 (7)0.0009 (6)
C140.0314 (11)0.0313 (11)0.0240 (9)0.0022 (9)0.0015 (8)0.0049 (8)
O150.0533 (10)0.0536 (11)0.0219 (7)−0.0213 (8)0.0002 (7)0.0032 (7)
C160.0371 (12)0.0358 (12)0.0259 (10)−0.0019 (9)0.0075 (8)0.0047 (8)
C170.0352 (12)0.0410 (13)0.0260 (9)−0.0113 (10)0.0089 (8)0.0041 (9)
C180.0392 (14)0.080 (2)0.0405 (14)−0.0095 (14)0.0002 (11)−0.0043 (13)
C190.069 (2)0.118 (3)0.0396 (15)−0.054 (2)0.0048 (15)−0.0204 (18)
C200.117 (3)0.058 (2)0.0525 (18)−0.054 (2)0.027 (2)−0.0082 (15)
C210.112 (3)0.0334 (15)0.0633 (18)−0.0212 (16)0.0105 (19)0.0129 (13)
C220.0641 (18)0.0387 (14)0.0457 (14)−0.0164 (13)−0.0073 (12)0.0132 (11)
C230.0330 (10)0.0254 (10)0.0177 (8)−0.0011 (9)−0.0014 (7)0.0018 (7)
C240.0357 (12)0.0290 (11)0.0291 (10)−0.0002 (9)0.0056 (9)0.0063 (8)
C250.0435 (13)0.0351 (12)0.0352 (12)0.0086 (10)0.0053 (10)0.0003 (9)
C260.0521 (14)0.0205 (10)0.0384 (12)−0.0024 (10)−0.0036 (10)0.0018 (9)
C270.0468 (14)0.0334 (12)0.0348 (11)−0.0126 (10)0.0026 (10)0.0074 (9)
C280.0381 (13)0.0320 (12)0.0263 (10)−0.0046 (9)0.0058 (9)−0.0004 (8)

Geometric parameters (Å, °)

S1—C6A1.755 (2)N13—C141.358 (3)
S1—C21.831 (2)N13—H130.9732
F1A—C201.405 (5)C14—O151.219 (2)
F1B—C201.429 (13)C14—C161.526 (3)
F2—C261.365 (2)C16—C171.503 (3)
C2—C31.522 (3)C16—H16A0.9900
C2—H2A0.9900C16—H16B0.9900
C2—H2B0.9900C17—C181.380 (3)
C3—N3A1.457 (3)C17—C221.391 (4)
C3—H3A0.9900C18—C191.412 (5)
C3—H3B0.9900C18—H180.9500
N3A—C6A1.353 (2)C19—C201.355 (6)
N3A—C41.393 (3)C19—H190.9500
C4—C51.377 (3)C20—C211.341 (5)
C4—C71.469 (3)C21—C221.385 (4)
C5—N61.394 (2)C21—H210.9500
C5—C231.475 (3)C22—H220.9500
N6—C6A1.313 (3)C23—C241.392 (3)
C7—C81.385 (3)C23—C281.394 (3)
C7—C121.398 (3)C24—C251.390 (3)
C8—C91.397 (3)C24—H240.9500
C8—H80.9500C25—C261.373 (3)
C9—N101.340 (3)C25—H250.9500
C9—N131.405 (3)C26—C271.367 (4)
N10—C111.338 (3)C27—C281.390 (3)
C11—C121.381 (3)C27—H270.9500
C11—H110.9500C28—H280.9500
C12—H120.9500
C6A—S1—C288.70 (10)O15—C14—C16121.9 (2)
C3—C2—S1107.26 (15)N13—C14—C16113.82 (17)
C3—C2—H2A110.3C17—C16—C14111.93 (17)
S1—C2—H2A110.3C17—C16—H16A109.2
C3—C2—H2B110.3C14—C16—H16A109.2
S1—C2—H2B110.3C17—C16—H16B109.2
H2A—C2—H2B108.5C14—C16—H16B109.2
N3A—C3—C2103.86 (16)H16A—C16—H16B107.9
N3A—C3—H3A111.0C18—C17—C22118.5 (3)
C2—C3—H3A111.0C18—C17—C16121.1 (2)
N3A—C3—H3B111.0C22—C17—C16120.2 (2)
C2—C3—H3B111.0C17—C18—C19119.4 (3)
H3A—C3—H3B109.0C17—C18—H18120.3
C6A—N3A—C4106.57 (16)C19—C18—H18120.3
C6A—N3A—C3116.46 (17)C20—C19—C18119.0 (3)
C4—N3A—C3135.62 (17)C20—C19—H19120.5
C5—C4—N3A104.88 (17)C18—C19—H19120.5
C5—C4—C7132.72 (19)C21—C20—C19123.3 (3)
N3A—C4—C7122.28 (17)C21—C20—F1A113.2 (4)
C4—C5—N6110.87 (18)C19—C20—F1A123.3 (4)
C4—C5—C23129.10 (17)C21—C20—F1B143.6 (7)
N6—C5—C23120.02 (16)C19—C20—F1B92.4 (6)
C6A—N6—C5103.95 (15)C20—C21—C22118.0 (3)
N6—C6A—N3A113.68 (17)C20—C21—H21121.0
N6—C6A—S1133.22 (15)C22—C21—H21121.0
N3A—C6A—S1112.93 (15)C21—C22—C17121.7 (3)
C8—C7—C12118.51 (17)C21—C22—H22119.2
C8—C7—C4121.22 (18)C17—C22—H22119.2
C12—C7—C4120.25 (18)C24—C23—C28118.57 (19)
C7—C8—C9118.56 (18)C24—C23—C5121.78 (19)
C7—C8—H8120.7C28—C23—C5119.65 (19)
C9—C8—H8120.7C25—C24—C23120.9 (2)
N10—C9—C8123.24 (19)C25—C24—H24119.6
N10—C9—N13112.57 (16)C23—C24—H24119.6
C8—C9—N13124.18 (18)C26—C25—C24118.4 (2)
C11—N10—C9117.27 (16)C26—C25—H25120.8
N10—C11—C12123.80 (19)C24—C25—H25120.8
N10—C11—H11118.1F2—C26—C27119.2 (2)
C12—C11—H11118.1F2—C26—C25118.0 (2)
C11—C12—C7118.56 (19)C27—C26—C25122.8 (2)
C11—C12—H12120.7C26—C27—C28118.4 (2)
C7—C12—H12120.7C26—C27—H27120.8
C14—N13—C9127.44 (16)C28—C27—H27120.8
C14—N13—H13127.6C27—C28—C23121.0 (2)
C9—N13—H13105.0C27—C28—H28119.5
O15—C14—N13124.24 (19)C23—C28—H28119.5
C6A—S1—C2—C3−27.8 (2)C4—C7—C12—C11−177.6 (2)
S1—C2—C3—N3A33.4 (2)N10—C9—N13—C14−176.67 (19)
C2—C3—N3A—C6A−25.1 (3)C8—C9—N13—C142.2 (3)
C2—C3—N3A—C4170.3 (2)C9—N13—C14—O150.0 (4)
C6A—N3A—C4—C52.2 (2)C9—N13—C14—C16−179.99 (19)
C3—N3A—C4—C5167.9 (3)O15—C14—C16—C1727.2 (3)
C6A—N3A—C4—C7−174.4 (2)N13—C14—C16—C17−152.78 (19)
C3—N3A—C4—C7−8.7 (4)C14—C16—C17—C18−74.3 (3)
N3A—C4—C5—N6−1.3 (2)C14—C16—C17—C22100.8 (2)
C7—C4—C5—N6174.8 (2)C22—C17—C18—C190.6 (4)
N3A—C4—C5—C23177.6 (2)C16—C17—C18—C19175.8 (2)
C7—C4—C5—C23−6.3 (4)C17—C18—C19—C20−0.6 (4)
C4—C5—N6—C6A−0.2 (3)C18—C19—C20—C210.1 (5)
C23—C5—N6—C6A−179.2 (2)C18—C19—C20—F1A−175.5 (3)
C5—N6—C6A—N3A1.7 (3)C18—C19—C20—F1B172.8 (7)
C5—N6—C6A—S1−173.1 (2)C19—C20—C21—C220.3 (5)
C4—N3A—C6A—N6−2.5 (3)F1A—C20—C21—C22176.3 (3)
C3—N3A—C6A—N6−171.4 (2)F1B—C20—C21—C22−167.3 (12)
C4—N3A—C6A—S1173.32 (16)C20—C21—C22—C17−0.2 (5)
C3—N3A—C6A—S14.5 (3)C18—C17—C22—C21−0.2 (4)
C2—S1—C6A—N6−170.9 (3)C16—C17—C22—C21−175.4 (3)
C2—S1—C6A—N3A14.27 (19)C4—C5—C23—C24−34.4 (3)
C5—C4—C7—C8140.0 (2)N6—C5—C23—C24144.5 (2)
N3A—C4—C7—C8−44.5 (3)C4—C5—C23—C28146.3 (2)
C5—C4—C7—C12−41.6 (4)N6—C5—C23—C28−34.9 (3)
N3A—C4—C7—C12133.9 (2)C28—C23—C24—C25−0.4 (3)
C12—C7—C8—C9−2.5 (3)C5—C23—C24—C25−179.7 (2)
C4—C7—C8—C9175.9 (2)C23—C24—C25—C260.5 (3)
C7—C8—C9—N102.4 (3)C24—C25—C26—F2179.8 (2)
C7—C8—C9—N13−176.35 (19)C24—C25—C26—C270.0 (4)
C8—C9—N10—C11−0.3 (3)F2—C26—C27—C28179.8 (2)
N13—C9—N10—C11178.53 (19)C25—C26—C27—C28−0.4 (4)
C9—N10—C11—C12−1.5 (3)C26—C27—C28—C230.5 (3)
N10—C11—C12—C71.3 (3)C24—C23—C28—C27−0.1 (3)
C8—C7—C12—C110.9 (3)C5—C23—C28—C27179.3 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N13—H13···N6i0.972.022.980 (2)171
C8—H8···O150.952.242.845 (3)120

Symmetry codes: (i) x−1/2, −y+1/2, z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IM2189).

References

  • Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst.32, 115–119.
  • Bruker (2006). APEX2, SAINT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
  • Ziegler, K., Hauser, D. R. J., Unger, A., Albrecht, W. & Laufer, S. (2009). ChemMedChem, 4, 1939–1948. [PubMed]

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