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Acta Crystallogr Sect E Struct Rep Online. 2008 July 1; 64(Pt 7): o1183–o1184.
Published online 2008 June 7. doi:  10.1107/S1600536808016000
PMCID: PMC2961725

Methyl 4-[5-(4-fluoro­phen­yl)-4-(pyridin-4-yl)-1H-imidazol-2-ylsulfan­yl]butanoate

Abstract

The title compound, C19H18FN3O2S, was synthesized in the course of studies on 2-alkyl­sufanylimidazoles as p38 mitogen-activated protein kinase inhibitors. The synthesis was achieved by nucleophilic substitution of 4-(4-fluoro­phen­yl)-5-(pyridin-4-yl)-1,3-dihydro­imidazole-2-thione with methyl 4-bromo­butanoate. The five-membered heterocycle makes dihedral angles of 32.4 (2) and 18.3 (2)° with the fluoro­phenyl and pyridinyl rings, respectively, indicating a low degree of conjugation between these rings. Intra­molecular C—H(...)N and inter­molecular N—H(...)N hydrogen bonds as well as C—H(...)π inter­actions seem to be effective in stabilization of the crystal structure.

Related literature

Substituted imidazoles as small-mol­ecule inhibitors of p38 MAP kinase have been reviewed by Peifer et al. (2006 [triangle]) and Wagner & Laufer (2006 [triangle]). For the preparation of 4-(4-fluoro­phen­yl)-5-(pyridin-4-yl)-1,3-dihydro­imidazole-2-thione, see: Lantos et al. (1988 [triangle]). For related literature, see: Laufer, Striegel & Wagner (2002 [triangle]); Laufer, Wagner & Kotschenreuther (2002 [triangle]); Laufer & Koch (2008 [triangle]); Wang et al. (1998 [triangle]); Peifer et al. (2007 [triangle]).

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Object name is e-64-o1183-scheme1.jpg

Experimental

Crystal data

  • C19H18FN3O2S
  • M r = 371.42
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1183-efi2.jpg
  • a = 18.494 (4) Å
  • b = 12.4367 (10) Å
  • c = 7.5255 (5) Å
  • V = 1730.9 (4) Å3
  • Z = 4
  • Cu Kα radiation
  • μ = 1.92 mm−1
  • T = 193 (2) K
  • 0.55 × 0.12 × 0.09 mm

Data collection

  • Enraf–Nonius CAD-4 diffractometer
  • Absorption correction: Gaussian (PLATON; Spek, 2003 [triangle]) T min = 0.61, T max = 0.85
  • 3363 measured reflections
  • 3086 independent reflections
  • 2869 reflections with I > 2σ(I)
  • R int = 0.051
  • 3 standard reflections frequency: 60 min intensity decay: 5%

Refinement

  • R[F 2 > 2σ(F 2)] = 0.076
  • wR(F 2) = 0.188
  • S = 1.14
  • 3086 reflections
  • 236 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 1.14 e Å−3
  • Δρmin = −0.60 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1307 Friedel pairs
  • Flack parameter: −0.02 (3)

Data collection: CAD-4 Software (Enraf–Nonius, 1989 [triangle]); cell refinement: CAD-4 Software; data reduction: CORINC (Dräger & Gattow, 1971 [triangle]); 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, 2003 [triangle]); software used to prepare material for publication: PLATON.

Table 1
Hydrogen-bond geometry (Å, °)
Table 2
Nonconventional C—H(...)X contacts (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808016000/bx2140sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808016000/bx2140Isup2.hkl

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

Acknowledgments

The authors acknowledge financial support from the EU, part of the EU-Craft Programme, Framework Project 6 ‘MACROCEPT’.

supplementary crystallographic information

Comment

The title compound was prepared in the course of our studies on 2-alkylsulfanyl-4-(4-fluorophenyl)-5-pyridinyl imidazoles as p38 mitogen-activated protein (MAP) kinase inhibitors. The p38 MAP kinase plays a central role for the biosynthesis and release of pro-inflammatory cytokines like TNF-α and IL-1β. Inhibition of p38 MAP kinase is therefore a promising therapeutic strategy for the treatment of inflammatory disorders like psoriasis, inflammatory bowel disease and rheumatoid arthritis. The fundamental SAR for the class of pyridinyl imidazole derivative as p38 MAP kinase inhibitors can be exemplified by the way SB203580 binds to the protein (Wang et al., 1998). There is a crucial hydrogen bond between the pyridin-4-yl moiety and Met109 of the enzyme. The 4-fluorophenyl ring binds to the hydrophobic region I, mainly gaining selectivity. Another possible ligand-protein interaction is a hydrogen bond between Lys53 and N3 of the imidazole core (Peifer et al., 2007).

The analysis of the crystal structure of methyl 4-(5-(4-fluorophenyl)-4-(pyridin-4-yl)-1H-imidazol-2-ylthio)butanoate (I) is shown in Figure 1. The crystal packing (Figure 2) shows that N5—H5 of the imidazole ring forms an intermolecular N–H···N hydrogen bond to pyridine (N17). The length of the hydrogen bond is 1.95Å (Table 1). Non-conventional C—H···X H-bonds are also present in addition to intermolecular N—H···N hydrogen interactions (Table 2).

Experimental

To a stirred solution of 4-(4-fluorophenyl)-5-(pyridin-4-yl)-1,3-dihydroimidazole-2-thione (0.74 mmol) and potassium tert-butoxide (0.77 mmol) in dry methanol (15 ml) was added under argon atmosphere after 15 min metyl 4-bromobutanoate (0.77 mmol). The solution was heated for 1 h to reflux temperature. After extraction with water and ethyl acetate the organic layer was washed twice with water, dried over sodium sulfate and evaporated under reduced pressure. The crude product was purified by flash chromatography (silica gel, dichloromethane - ethyl acetate 1:1 to 2:3) to yield methyl 4-(5-(4-fluorophenyl)-4-(pyridin-4-yl)-1H-imidazol-2-ylthio)butanoate (I) (49%) as a colorless solid. Compound I was crystallized from methanol.

Refinement

Hydrogen atoms attached to carbons were placed at calculated positions with C—H = 0.95Å (aromatic) or 0.98–0.99 Å (sp3 C-atom). H-atom bonded to N5 was located from a difference Fourier map (N—H = 0.9 Å). 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).

Figures

Fig. 1.
View of compound I. Displacement ellipsoids are drawn at the 50% probability level. H atoms are depicted as circles of arbitrary size.
Fig. 2.
Part of the crystal packing of compound I. The hydrogen bond is shown with dashed lines. View along c axis. N17_b:x + 1/2, 1 - y, z

Crystal data

C19H18FN3O2SF000 = 776
Mr = 371.42Dx = 1.425 Mg m3
Orthorhombic, Pca21Cu Kα radiation λ = 1.54178 Å
Hall symbol: P 2c -2acCell parameters from 25 reflections
a = 18.494 (4) Åθ = 31–44º
b = 12.4367 (10) ŵ = 1.92 mm1
c = 7.5255 (5) ÅT = 193 (2) K
V = 1730.9 (4) Å3Needle, colourless
Z = 40.55 × 0.12 × 0.09 mm

Data collection

Enraf–Nonius CAD-4 diffractometerRint = 0.051
Monochromator: graphiteθmax = 70.0º
T = 193(2) Kθmin = 3.6º
ω/2θ scansh = −22→22
Absorption correction: gaussian(PLATON; Spek, 2003)k = −15→15
Tmin = 0.61, Tmax = 0.85l = −7→9
3363 measured reflections3 standard reflections
3086 independent reflections every 60 min
2869 reflections with I > 2σ(I) intensity decay: 5%

Refinement

Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.076  w = 1/[σ2(Fo2) + (0.1374P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.188(Δ/σ)max < 0.001
S = 1.14Δρmax = 1.14 e Å3
3086 reflectionsΔρmin = −0.60 e Å3
236 parametersExtinction correction: none
1 restraintAbsolute structure: Flack (1983), 1307 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: −0.02 (3)
Secondary atom site location: difference Fourier map

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
C10.3643 (2)0.3750 (3)0.3172 (5)0.0204 (8)
N20.29502 (16)0.3630 (3)0.3227 (4)0.0203 (7)
C30.26668 (19)0.4629 (3)0.2819 (5)0.0179 (7)
C40.32215 (19)0.5351 (3)0.2524 (5)0.0183 (8)
N50.38455 (15)0.4764 (2)0.2738 (4)0.0173 (6)
H50.43140.49670.27110.021*
S60.42920 (5)0.27420 (8)0.35250 (18)0.0298 (3)
C70.3694 (2)0.1589 (3)0.3710 (7)0.0300 (9)
H7A0.33120.16500.27960.036*
H7B0.39750.09290.34560.036*
C80.3338 (2)0.1474 (4)0.5527 (8)0.0371 (12)
H8A0.29670.09010.54630.044*
H8B0.30890.21550.58250.044*
C90.3870 (3)0.1202 (4)0.7011 (8)0.0451 (13)
H9A0.42390.17780.70610.054*
H9B0.36040.12140.81530.054*
C100.4252 (2)0.0150 (4)0.6867 (7)0.0360 (11)
O110.4808 (2)−0.0057 (4)0.7602 (7)0.0621 (12)
O120.38975 (17)−0.0571 (2)0.5875 (5)0.0368 (8)
C130.4252 (3)−0.1576 (4)0.5589 (7)0.0413 (12)
H13A0.4738−0.14470.51150.062*
H13B0.3973−0.20040.47370.062*
H13C0.4288−0.19650.67170.062*
C140.1875 (2)0.4721 (3)0.2746 (5)0.0189 (7)
C150.14573 (19)0.3934 (3)0.3609 (6)0.0225 (7)
H150.16840.33740.42600.027*
C160.07186 (19)0.3987 (3)0.3501 (7)0.0267 (8)
H160.04470.34390.40760.032*
N170.03515 (16)0.4759 (3)0.2637 (6)0.0270 (8)
C180.0753 (2)0.5502 (3)0.1816 (6)0.0244 (9)
H180.05090.60560.11860.029*
C190.14979 (19)0.5514 (3)0.1825 (5)0.0201 (7)
H190.17530.60610.12070.024*
C200.32620 (18)0.6506 (3)0.2109 (5)0.0185 (8)
C210.2750 (2)0.7236 (3)0.2741 (6)0.0217 (8)
H210.23730.69880.34930.026*
C220.2782 (2)0.8313 (3)0.2294 (6)0.0261 (9)
H220.24230.88010.27040.031*
C230.3342 (2)0.8664 (3)0.1244 (6)0.0274 (9)
C240.3875 (2)0.7984 (4)0.0657 (6)0.0267 (9)
H240.42650.8252−0.00320.032*
C250.38349 (19)0.6910 (3)0.1081 (6)0.0220 (8)
H250.42010.64340.06720.026*
F260.33578 (16)0.9714 (2)0.0773 (4)0.0405 (7)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0269 (17)0.0264 (18)0.008 (2)0.0036 (14)−0.0006 (13)0.0032 (14)
N20.0239 (14)0.0260 (15)0.0110 (19)0.0029 (11)0.0001 (12)−0.0007 (12)
C30.0263 (18)0.0242 (17)0.0031 (17)0.0023 (13)0.0009 (14)−0.0015 (14)
C40.0211 (16)0.032 (2)0.0019 (18)0.0020 (14)0.0004 (13)−0.0021 (14)
N50.0177 (13)0.0271 (16)0.0072 (15)0.0012 (11)−0.0002 (12)−0.0022 (12)
S60.0229 (5)0.0303 (5)0.0362 (7)0.0068 (3)0.0024 (4)0.0086 (4)
C70.037 (2)0.0238 (18)0.029 (3)0.0044 (15)−0.005 (2)0.0005 (17)
C80.039 (2)0.033 (2)0.039 (3)0.0064 (18)0.011 (2)0.013 (2)
C90.078 (4)0.033 (2)0.024 (3)0.004 (2)0.005 (3)0.002 (2)
C100.045 (3)0.037 (2)0.026 (3)−0.0026 (18)0.002 (2)0.004 (2)
O110.059 (2)0.061 (2)0.067 (3)0.009 (2)−0.027 (2)−0.019 (2)
O120.0440 (17)0.0313 (16)0.035 (2)0.0030 (12)−0.0122 (15)0.0029 (15)
C130.060 (3)0.035 (2)0.029 (3)0.008 (2)−0.014 (2)0.002 (2)
C140.0255 (17)0.0277 (17)0.0036 (17)−0.0002 (14)0.0021 (14)−0.0047 (14)
C150.0294 (17)0.0239 (16)0.014 (2)0.0004 (14)0.0036 (18)−0.0007 (15)
C160.0281 (18)0.0265 (18)0.025 (2)−0.0021 (14)0.0060 (18)−0.0044 (19)
N170.0193 (14)0.0349 (18)0.027 (2)−0.0003 (13)−0.0008 (13)−0.0080 (15)
C180.033 (2)0.031 (2)0.010 (2)0.0058 (15)−0.0052 (16)−0.0029 (17)
C190.0266 (18)0.0275 (17)0.006 (2)−0.0008 (14)0.0003 (14)−0.0004 (15)
C200.0224 (17)0.0276 (18)0.0055 (18)−0.0017 (13)−0.0034 (13)−0.0007 (14)
C210.0266 (18)0.031 (2)0.0076 (18)0.0008 (14)−0.0018 (15)0.0005 (15)
C220.034 (2)0.0285 (19)0.016 (2)0.0043 (16)−0.0011 (16)−0.0031 (16)
C230.037 (2)0.0259 (19)0.020 (2)−0.0043 (15)−0.0059 (17)0.0033 (16)
C240.031 (2)0.036 (2)0.013 (2)−0.0078 (16)−0.0001 (15)0.0056 (17)
C250.0221 (17)0.0320 (19)0.012 (2)−0.0004 (14)0.0006 (15)−0.0026 (16)
F260.0596 (17)0.0272 (12)0.0346 (18)−0.0027 (11)0.0013 (13)0.0072 (11)

Geometric parameters (Å, °)

C1—N21.290 (5)C13—H13B0.9800
C1—N51.356 (5)C13—H13C0.9800
C1—S61.756 (4)C14—C191.392 (5)
N2—C31.384 (5)C14—C151.405 (5)
C3—C41.381 (5)C15—C161.370 (5)
C3—C141.470 (5)C15—H150.9500
C4—N51.375 (5)C16—N171.344 (6)
C4—C201.471 (5)C16—H160.9500
N5—H50.9032N17—C181.336 (6)
S6—C71.816 (4)C18—C191.378 (5)
C7—C81.525 (7)C18—H180.9500
C7—H7A0.9900C19—H190.9500
C7—H7B0.9900C20—C211.395 (5)
C8—C91.527 (8)C20—C251.405 (5)
C8—H8A0.9900C21—C221.383 (5)
C8—H8B0.9900C21—H210.9500
C9—C101.491 (6)C22—C231.374 (6)
C9—H9A0.9900C22—H220.9500
C9—H9B0.9900C23—F261.354 (5)
C10—O111.196 (6)C23—C241.371 (6)
C10—O121.339 (6)C24—C251.375 (6)
O12—C131.427 (6)C24—H240.9500
C13—H13A0.9800C25—H250.9500
N2—C1—N5113.0 (3)H13A—C13—H13B109.5
N2—C1—S6126.2 (3)O12—C13—H13C109.5
N5—C1—S6120.7 (3)H13A—C13—H13C109.5
C1—N2—C3105.3 (3)H13B—C13—H13C109.5
C4—C3—N2109.8 (3)C19—C14—C15116.6 (3)
C4—C3—C14133.1 (3)C19—C14—C3124.9 (3)
N2—C3—C14117.1 (3)C15—C14—C3118.4 (3)
N5—C4—C3105.0 (3)C16—C15—C14119.2 (4)
N5—C4—C20120.0 (3)C16—C15—H15120.4
C3—C4—C20134.9 (3)C14—C15—H15120.4
C1—N5—C4106.9 (3)N17—C16—C15124.5 (4)
C1—N5—H5122.1N17—C16—H16117.8
C4—N5—H5130.9C15—C16—H16117.8
C1—S6—C799.14 (18)C18—N17—C16115.9 (3)
C8—C7—S6114.0 (3)N17—C18—C19124.1 (4)
C8—C7—H7A108.8N17—C18—H18117.9
S6—C7—H7A108.8C19—C18—H18117.9
C8—C7—H7B108.8C18—C19—C14119.7 (4)
S6—C7—H7B108.8C18—C19—H19120.2
H7A—C7—H7B107.7C14—C19—H19120.2
C7—C8—C9113.4 (4)C21—C20—C25117.8 (4)
C7—C8—H8A108.9C21—C20—C4121.9 (3)
C9—C8—H8A108.9C25—C20—C4120.3 (3)
C7—C8—H8B108.9C22—C21—C20121.3 (4)
C9—C8—H8B108.9C22—C21—H21119.4
H8A—C8—H8B107.7C20—C21—H21119.4
C10—C9—C8116.6 (4)C23—C22—C21118.7 (4)
C10—C9—H9A108.2C23—C22—H22120.7
C8—C9—H9A108.2C21—C22—H22120.7
C10—C9—H9B108.2F26—C23—C24119.7 (4)
C8—C9—H9B108.2F26—C23—C22118.3 (4)
H9A—C9—H9B107.3C24—C23—C22122.1 (4)
O11—C10—O12122.4 (5)C23—C24—C25119.1 (4)
O11—C10—C9124.3 (5)C23—C24—H24120.5
O12—C10—C9113.3 (4)C25—C24—H24120.5
C10—O12—C13116.5 (4)C24—C25—C20121.0 (4)
O12—C13—H13A109.5C24—C25—H25119.5
O12—C13—H13B109.5C20—C25—H25119.5
N5—C1—N2—C3−0.5 (4)N2—C3—C14—C1519.8 (5)
S6—C1—N2—C3−178.3 (3)C19—C14—C15—C160.1 (6)
C1—N2—C3—C4−0.2 (4)C3—C14—C15—C16−177.7 (4)
C1—N2—C3—C14178.7 (3)C14—C15—C16—N17−1.2 (7)
N2—C3—C4—N50.8 (4)C15—C16—N17—C181.3 (7)
C14—C3—C4—N5−177.8 (4)C16—N17—C18—C19−0.4 (6)
N2—C3—C4—C20−177.7 (4)N17—C18—C19—C14−0.5 (6)
C14—C3—C4—C203.6 (7)C15—C14—C19—C180.7 (6)
N2—C1—N5—C41.0 (4)C3—C14—C19—C18178.3 (3)
S6—C1—N5—C4179.0 (3)N5—C4—C20—C21−146.2 (4)
C3—C4—N5—C1−1.1 (4)C3—C4—C20—C2132.2 (7)
C20—C4—N5—C1177.7 (4)N5—C4—C20—C2532.5 (5)
N2—C1—S6—C75.7 (4)C3—C4—C20—C25−149.2 (4)
N5—C1—S6—C7−172.0 (3)C25—C20—C21—C223.4 (6)
C1—S6—C7—C8−80.0 (3)C4—C20—C21—C22−177.9 (4)
S6—C7—C8—C9−67.3 (4)C20—C21—C22—C23−1.7 (6)
C7—C8—C9—C10−63.6 (6)C21—C22—C23—F26178.2 (4)
C8—C9—C10—O11158.8 (6)C21—C22—C23—C24−1.2 (7)
C8—C9—C10—O12−23.6 (6)F26—C23—C24—C25−177.2 (4)
O11—C10—O12—C13−6.0 (8)C22—C23—C24—C252.2 (7)
C9—C10—O12—C13176.3 (4)C23—C24—C25—C20−0.4 (6)
C4—C3—C14—C1920.7 (7)C21—C20—C25—C24−2.4 (6)
N2—C3—C14—C19−157.8 (4)C4—C20—C25—C24178.9 (4)
C4—C3—C14—C15−161.6 (4)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N5—H5···N17i0.901.952.849 (4)174

Symmetry codes: (i) x+1/2, −y+1, z.

Table 2 Nonconventional C–H···X contacts (Å, °).

C–H···AC–HH···AC–H···AC···A
C13–H13B···Cg1ii0.982.651563.566 (6)
C7–H7A···N20.992.571002.910 (5)

Symmetry code: (ii) x, y-1, z. Cg1 is the centroid of the C20–C25 ring.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BX2140).

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.
  • Dräger, M. & Gattow, G. (1971). Acta Chem. Scand.25, 761–762.
  • Enraf–Nonius (1989). CAD-4 Software Enraf–Nonius, Delft, The Netherlands.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Lantos, I., Gombatz, K., McGuire, M., Pridgen, L., Remich, J. & Shilcrat, S. (1988). J. Org. Chem.53, 4223–4227.
  • Laufer, S. & Koch, P. (2008). Org. Biomol. Chem.6, 437–439. [PubMed]
  • Laufer, S. A., Striegel, H.-G. & Wagner, G. K. (2002). J. Med. Chem.45, 4695–4705. [PubMed]
  • Laufer, S., Wagner, G. & Kotschenreuther, D. (2002). Angew. Chem. Int. Ed.41, 2290–2293. [PubMed]
  • Peifer, C., Kinkel, K., Abadleh, M., Schollmeyer, D. & Laufer, S. (2007). J. Med. Chem.50, 1213–1221. [PubMed]
  • Peifer, C., Wagner, G. & Laufer, S. (2006). Curr. Top. Med. Chem.6, 113–149. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.
  • Wagner, G. & Laufer, S. (2006). Med. Res. Rev.26, 1–62. [PubMed]
  • Wang, Z., Canagarajah, B. J., Boehm, J. C., Kassisa, S., Cobb, M. H., Young, P. R., Abdel-Meguid, S., Adams, J. L. & Goldsmith, E. J. (1998). Structure, 6, 1117–1128. [PubMed]

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