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Acta Crystallogr Sect E Struct Rep Online. 2010 November 1; 66(Pt 11): o2856–o2857.
Published online 2010 October 20. doi:  10.1107/S1600536810041061
PMCID: PMC3009236

N-[(2-Chloro-8-methyl­quinolin-3-yl)meth­yl]-4-meth­oxy­aniline

Abstract

In the title compound, C18H17ClN2O, the quinoline ring system is essentially planar; the r.m.s. deviation for the non-H atoms is 0.04 Å with a maximum deviation from the mean plane of 0.026 (4) Å for the C atom bonded to the –CH2– group. The meth­oxy-substituted benzene ring forms a dihedral angle of 70.22 (4)° with this ring system. The crystal structure can be described as zigzag layers in which the quinoline ring systems are parallel to (011) and molecules are connected via inter­molecular N—H(...)N hydrogen bonds, forming chains along [100]. The crystal studied was an inversion twin with a 0.86 (5):0.14 (5) domain ratio.

Related literature

For background to quinoline compounds, see: Elderfield (1960 [triangle]); Wright et al. (2001 [triangle]); Sahu et al. (2002 [triangle]); Bringmann et al. (2004 [triangle]); Kournetsov et al. (2005 [triangle]). For the biological and pharmaceutical applications of quinolines, see: Albert & Ritchie (1955 [triangle]); Mouzine et al. (1980 [triangle]); Lyle & Keefer (1967 [triangle]). For the general synthesis of quinolines, see: Cope & Ciganek (1963 [triangle]); Ohta et al. (1989 [triangle]); Hatanaka & Ojima (1981 [triangle]); Smith (1994 [triangle]); Borch et al. (1971 [triangle]). For related structures, see: Boulcina et al. (2007 [triangle], 2008 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2856-scheme1.jpg

Experimental

Crystal data

  • C18H17ClN2O
  • M r = 312.79
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2856-efi1.jpg
  • a = 7.3067 (1) Å
  • b = 17.7803 (4) Å
  • c = 22.8221 (5) Å
  • V = 2964.94 (10) Å3
  • Z = 8
  • Mo Kα radiation
  • μ = 0.26 mm−1
  • T = 100 K
  • 0.41 × 0.29 × 0.17 mm

Data collection

  • Bruker APEXII diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2002 [triangle]) T min = 0.857, T max = 0.957
  • 15861 measured reflections
  • 3383 independent reflections
  • 3303 reflections with I > 2σ(I)
  • R int = 0.030

Refinement

  • R[F 2 > 2σ(F 2)] = 0.027
  • wR(F 2) = 0.070
  • S = 1.05
  • 3383 reflections
  • 205 parameters
  • 1 restraint
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.30 e Å−3
  • Δρmin = −0.17 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1557 Friedel pairs
  • Flack parameter: 0.14 (5)

Data collection: APEX2 (Bruker,2001 [triangle]); cell refinement: SAINT (Bruker, 2001 [triangle]); data reduction: SAINT; program(s) used to solve structure: SIR2002 (Burla et al., 2003 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]) and DIAMOND (Brandenburg & Berndt, 2001 [triangle]); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810041061/lh5139sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810041061/lh5139Isup2.hkl

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

Acknowledgments

We are grateful to all personnel of the PHYSYNOR Laboratory, Université Mentouri–Constantine, Algeria, for their assistance.

supplementary crystallographic information

Comment

The importance of quinoline and its derivatives is well recognized by synthetic and biological chemists (Elderfield et al., 1960; Wright et al., 2001; Sahu et al., 2002; Bringmann et al., 2004; Kournetsov et al., 2005). Compounds possessing this ring system such as aminoquinolines, have wide applications as drugs and pharmaceuticals. Many derivatives of aminoquinolines have been reported as plant resistance factors as topical antiseptic (Albert et al. 1955), analgesic (Mouzine et al., 1980) and antimalarials (Lyle et al., 1967). Therefore, considerable efforts have been directed towards the preparation and synthetic manipulation of these molecules. Of the many methods available for the synthesis of amines, the most widely used is the reduction of amides (Cope et al., 1963) and nitro compounds (Ohta et al., 1989) with LiAlH4. Reduction of azides (Hatanaka et al., 1981) and nitro compounds (Smith, 1994) with H2/Pd have been also reported. Another important and simple method has been disclosed by Borch et al. (1971) which employs NaBH3CN at pH≈6 to reduce imines to the corresponding amines. In an ongoing project in our laboratory based on the synthesis of functionalized quinolines (Boulcina et al., 2007; 2008), we require an efficient route for the synthesis and transformations of these heterocycles. Herein, we report an efficient and general procedure for the synthesis of a new aminoquinoline derivative derived from 2-chloro-8-methyl-3-formylquinolines. The use of NaBH3CN as a reducing agent of the corresponding imines was the methodology of choice to accomplish this task. The crystal structure of the title compound (I) is determined herein.

The molecular structure and the atom-numbering scheme of (I) are shown in Fig. 1. The quinoline ring system is essentially planar; the rms deviation for the non-H atoms is 0.04 Å with a maximum deviation from the mean plane of -0.026 (4)Å for the C atom bonded to the -CH2- group. The methoxy substituted benzene ring forms a dihedral of 70.22 (4)° with this ring system. The crystal structure can be described as zig-zag layers in which the quinoline ring systems are parallel to the (011) plane and moleclues are connected via intermolecular N—H···N hydrogen bond forming chains along [100]. The crystal is an inversion twin with a 0.86 (5):0.14 (5) ratio of domains.

Experimental

A mixture of 2-chloro-8-methyl-3-formylquinoline (5 mmol) and 4-methoxyaniline (5 mmol) in methanol (10 ml) was stirred at ambient temperature. On completion of the reaction, as indicated by TLC, the mixture was then filtered and the resulting product was washed with cold methanol. The product thus obtained as slightly yellow powder, could be used in the next step without purification. Further recrystallization from methanol yields pure imine. The appropriate imine (1 mmol) and NaBH3CN (3 mmol) in methanol (10 ml) were stirred for 24 h, diluted with cold water (20 ml), and left for several hours. The resulting solid was filtered off, washed with water, then with ethanol and with hexane. N-((2-chloro-8-methylquinolin-3-yl)methyl)-4-methoxybenzenamine was recrystallized from ethanol and identified by IR, 1H and 13C NMR spectroscopies. Crystals of the title compound were obtained by slow crystallization from a methanol solution.

Refinement

All H atoms were vizible in difference Fourier maps but were introduced in calculated positions and treated as riding on their parent C atom (with C—H = 0.93–0.97Å and Uiso(H) =1.2 or 1.5(Ueqcarrier atom)), except for H13N which was located in a difference Fourier map and refined isotropically.

Figures

Fig. 1.
The molecular structure of the title compound with the atomic labelling scheme. Displacement are drawn at the 50% probability level.
Fig. 2.
Part of the of the layered crystal packing of (I) viewed along the c axis (hydrogen bonds [N—H···N] are shown as dashed line between layers).

Crystal data

C18H17ClN2OF(000) = 1312
Mr = 312.79Dx = 1.401 Mg m3
Orthorhombic, C2cbMo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2bc 2Cell parameters from 9705 reflections
a = 7.3067 (1) Åθ = 2.3–27.4°
b = 17.7803 (4) ŵ = 0.26 mm1
c = 22.8221 (5) ÅT = 100 K
V = 2964.94 (10) Å3Prism, colourless
Z = 80.41 × 0.29 × 0.17 mm

Data collection

Bruker APEXII diffractometer3303 reflections with I > 2σ(I)
graphiteRint = 0.030
CCD rotation images, thin slices scansθmax = 27.4°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 2002)h = −9→9
Tmin = 0.857, Tmax = 0.957k = −22→22
15861 measured reflectionsl = −29→29
3383 independent reflections

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.027H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.070w = 1/[σ2(Fo2) + (0.0402P)2 + 1.310P] where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
3383 reflectionsΔρmax = 0.30 e Å3
205 parametersΔρmin = −0.17 e Å3
1 restraintAbsolute structure: Flack (1983), 1557 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.14 (5)

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
Cl10.66000 (6)0.143865 (16)0.747584 (13)0.01770 (8)
C10.72948 (19)0.05005 (8)0.75340 (5)0.0142 (3)
N20.74170 (16)0.02403 (6)0.80680 (5)0.0146 (2)
C30.79448 (18)−0.04968 (7)0.81373 (6)0.0140 (2)
C40.80333 (18)−0.08019 (8)0.87155 (6)0.0161 (3)
C50.7535 (2)−0.03278 (8)0.92397 (6)0.0218 (3)
H5A0.6239−0.02400.92420.033*
H5B0.81680.01450.92190.033*
H5C0.7881−0.05860.95920.033*
C60.85641 (19)−0.15425 (8)0.87761 (6)0.0187 (3)
H60.8633−0.17460.91510.022*
C70.9006 (2)−0.20031 (8)0.82926 (6)0.0206 (3)
H70.9356−0.25000.83520.025*
C80.8918 (2)−0.17158 (8)0.77354 (6)0.0187 (3)
H80.9215−0.20170.74160.022*
C90.83755 (19)−0.09606 (8)0.76480 (6)0.0150 (3)
C100.81977 (18)−0.06374 (8)0.70812 (6)0.0161 (3)
H100.8462−0.09280.67530.019*
C110.76461 (18)0.00913 (8)0.70091 (5)0.0152 (3)
C120.7358 (2)0.04066 (8)0.64019 (5)0.0171 (3)
H12A0.7357−0.00030.61210.021*
H12B0.61700.06490.63840.021*
N130.87651 (16)0.09478 (6)0.62391 (5)0.0162 (2)
C140.87924 (19)0.12075 (7)0.56569 (5)0.0143 (3)
C150.74893 (19)0.09871 (7)0.52389 (6)0.0161 (3)
H150.66040.06340.53380.019*
C160.75084 (19)0.12924 (8)0.46776 (6)0.0164 (3)
H160.66330.11410.44060.020*
C170.88177 (19)0.18205 (7)0.45168 (5)0.0159 (3)
C181.01471 (19)0.20355 (8)0.49223 (6)0.0171 (3)
H181.10450.23810.48180.021*
C191.01231 (18)0.17304 (8)0.54846 (6)0.0164 (3)
H191.10130.18780.57530.020*
O200.86737 (15)0.21049 (6)0.39555 (4)0.0202 (2)
C210.9605 (2)0.27960 (9)0.38392 (6)0.0220 (3)
H21A0.93700.31450.41510.033*
H21B0.91730.30030.34760.033*
H21C1.08970.27040.38120.033*
H13N0.978 (4)0.0849 (14)0.6370 (11)0.050*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cl10.02077 (15)0.01491 (14)0.01743 (14)0.00316 (14)0.00039 (13)0.00172 (12)
C10.0131 (6)0.0119 (6)0.0177 (6)−0.0001 (5)0.0003 (5)0.0017 (5)
N20.0130 (5)0.0160 (5)0.0146 (5)−0.0004 (4)−0.0006 (4)−0.0001 (4)
C30.0122 (6)0.0152 (6)0.0147 (5)−0.0019 (5)−0.0010 (5)0.0015 (5)
C40.0153 (6)0.0188 (6)0.0143 (6)−0.0008 (5)−0.0016 (5)0.0011 (5)
C50.0307 (8)0.0225 (7)0.0121 (6)0.0003 (6)−0.0002 (6)0.0014 (5)
C60.0178 (6)0.0210 (7)0.0172 (6)−0.0019 (5)−0.0030 (5)0.0062 (5)
C70.0208 (6)0.0161 (6)0.0249 (7)0.0008 (6)−0.0036 (6)0.0033 (5)
C80.0194 (7)0.0165 (6)0.0202 (6)0.0002 (6)0.0006 (6)−0.0018 (5)
C90.0134 (6)0.0156 (6)0.0159 (6)−0.0018 (5)−0.0004 (5)0.0011 (5)
C100.0156 (6)0.0183 (6)0.0143 (6)−0.0024 (5)0.0015 (5)−0.0013 (5)
C110.0138 (6)0.0185 (7)0.0133 (6)−0.0027 (5)−0.0002 (5)0.0004 (5)
C120.0204 (6)0.0178 (6)0.0131 (6)−0.0035 (5)−0.0009 (5)0.0020 (5)
N130.0162 (6)0.0189 (6)0.0134 (5)−0.0011 (5)−0.0011 (4)0.0022 (4)
C140.0175 (7)0.0135 (5)0.0120 (6)0.0032 (5)0.0013 (5)−0.0005 (5)
C150.0173 (6)0.0140 (6)0.0169 (6)−0.0018 (5)0.0012 (5)−0.0004 (5)
C160.0175 (7)0.0164 (6)0.0153 (6)0.0006 (5)−0.0021 (5)−0.0032 (5)
C170.0192 (6)0.0164 (6)0.0120 (6)0.0026 (6)0.0013 (5)0.0006 (5)
C180.0174 (6)0.0188 (7)0.0152 (6)−0.0016 (5)0.0022 (5)0.0003 (5)
C190.0158 (6)0.0195 (7)0.0140 (6)−0.0005 (5)−0.0009 (5)−0.0021 (5)
O200.0276 (6)0.0208 (5)0.0122 (4)−0.0029 (4)−0.0006 (4)0.0022 (4)
C210.0216 (7)0.0249 (7)0.0194 (7)−0.0013 (6)0.0026 (5)0.0070 (6)

Geometric parameters (Å, °)

Cl1—C11.7486 (14)C12—N131.4566 (18)
C1—N21.3067 (16)C12—H12A0.9700
C1—C111.4249 (18)C12—H12B0.9700
N2—C31.3752 (18)N13—C141.4068 (16)
C3—C91.4236 (19)N13—H13N0.82 (3)
C3—C41.4281 (18)C14—C191.4016 (19)
C4—C61.3795 (19)C14—C151.4036 (19)
C4—C51.5082 (19)C15—C161.3913 (18)
C5—H5A0.9600C15—H150.9300
C5—H5B0.9600C16—C171.390 (2)
C5—H5C0.9600C16—H160.9300
C6—C71.411 (2)C17—O201.3812 (15)
C6—H60.9300C17—C181.395 (2)
C7—C81.3718 (19)C18—C191.3935 (19)
C7—H70.9300C18—H180.9300
C8—C91.4143 (19)C19—H190.9300
C8—H80.9300O20—C211.4294 (18)
C9—C101.4213 (19)C21—H21A0.9600
C10—C111.3669 (19)C21—H21B0.9600
C10—H100.9300C21—H21C0.9600
C11—C121.5097 (17)
N2—C1—C11126.23 (13)N13—C12—C11112.39 (11)
N2—C1—Cl1115.37 (10)N13—C12—H12A109.1
C11—C1—Cl1118.40 (10)C11—C12—H12A109.1
C1—N2—C3117.64 (11)N13—C12—H12B109.1
N2—C3—C9121.59 (12)C11—C12—H12B109.1
N2—C3—C4118.75 (12)H12A—C12—H12B107.9
C9—C3—C4119.65 (12)C14—N13—C12117.89 (11)
C6—C4—C3117.90 (12)C14—N13—H13N113.6 (18)
C6—C4—C5121.45 (12)C12—N13—H13N114.0 (18)
C3—C4—C5120.64 (12)C19—C14—C15117.72 (12)
C4—C5—H5A109.5C19—C14—N13119.50 (12)
C4—C5—H5B109.5C15—C14—N13122.73 (12)
H5A—C5—H5B109.5C16—C15—C14120.67 (12)
C4—C5—H5C109.5C16—C15—H15119.7
H5A—C5—H5C109.5C14—C15—H15119.7
H5B—C5—H5C109.5C17—C16—C15120.90 (12)
C4—C6—C7122.67 (13)C17—C16—H16119.5
C4—C6—H6118.7C15—C16—H16119.5
C7—C6—H6118.7O20—C17—C16116.09 (12)
C8—C7—C6119.86 (13)O20—C17—C18124.60 (12)
C8—C7—H7120.1C16—C17—C18119.30 (12)
C6—C7—H7120.1C19—C18—C17119.70 (13)
C7—C8—C9119.83 (13)C19—C18—H18120.1
C7—C8—H8120.1C17—C18—H18120.1
C9—C8—H8120.1C18—C19—C14121.69 (12)
C8—C9—C10122.55 (13)C18—C19—H19119.2
C8—C9—C3120.08 (12)C14—C19—H19119.2
C10—C9—C3117.36 (12)C17—O20—C21116.79 (11)
C11—C10—C9121.32 (13)O20—C21—H21A109.5
C11—C10—H10119.3O20—C21—H21B109.5
C9—C10—H10119.3H21A—C21—H21B109.5
C10—C11—C1115.84 (12)O20—C21—H21C109.5
C10—C11—C12120.24 (11)H21A—C21—H21C109.5
C1—C11—C12123.85 (12)H21B—C21—H21C109.5
C11—C1—N2—C30.4 (2)N2—C1—C11—C10−1.4 (2)
Cl1—C1—N2—C3179.51 (10)Cl1—C1—C11—C10179.53 (10)
C1—N2—C3—C91.04 (19)N2—C1—C11—C12175.65 (14)
C1—N2—C3—C4−178.05 (13)Cl1—C1—C11—C12−3.40 (19)
N2—C3—C4—C6179.95 (12)C10—C11—C12—N13−108.76 (14)
C9—C3—C4—C60.83 (19)C1—C11—C12—N1374.30 (17)
N2—C3—C4—C50.7 (2)C11—C12—N13—C14171.73 (11)
C9—C3—C4—C5−178.37 (13)C12—N13—C14—C19179.78 (13)
C3—C4—C6—C7−0.4 (2)C12—N13—C14—C152.33 (19)
C5—C4—C6—C7178.83 (14)C19—C14—C15—C16−1.26 (19)
C4—C6—C7—C80.1 (2)N13—C14—C15—C16176.24 (12)
C6—C7—C8—C9−0.3 (2)C14—C15—C16—C170.2 (2)
C7—C8—C9—C10−177.82 (13)C15—C16—C17—O20−177.93 (12)
C7—C8—C9—C30.8 (2)C15—C16—C17—C181.1 (2)
N2—C3—C9—C8179.84 (13)O20—C17—C18—C19177.70 (12)
C4—C3—C9—C8−1.1 (2)C16—C17—C18—C19−1.3 (2)
N2—C3—C9—C10−1.44 (19)C17—C18—C19—C140.1 (2)
C4—C3—C9—C10177.64 (12)C15—C14—C19—C181.1 (2)
C8—C9—C10—C11179.08 (14)N13—C14—C19—C18−176.46 (12)
C3—C9—C10—C110.40 (19)C16—C17—O20—C21161.27 (12)
C9—C10—C11—C10.91 (19)C18—C17—O20—C21−17.73 (19)
C9—C10—C11—C12−176.27 (13)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N13—H13N···N2i0.82 (3)2.56 (3)3.3471 (16)163 (2)

Symmetry codes: (i) x+1/2, y, −z+3/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5139).

References

  • Albert, A. & Ritchie, B. (1955). Org. Synth. Coll.3, 53–55.
  • Borch, R. F., Bernstein, M. D. & Durst, H. D. (1971). J. Am. Chem. Soc.93, 2897–2904.
  • Boulcina, R., Belfaitah, A., Rhouati, S. & Debache, A. (2008). J. Soc. Alger. Chim.18, 61–70.
  • Boulcina, R., Bouacida, S., Roisnel, T. & Debache, A. (2007). Acta Cryst. E63, o3635–o3636.
  • Brandenburg, K. & Berndt, M. (2001). DIAMOND Crystal Impact, Bonn, Germany.
  • Bringmann, G., Reichert, Y. & Kane, V. (2004). Tetrahedron, 60, 3539–3574.
  • Bruker (2001). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst.38, 381–388.
  • Cope, A. C. & Ciganek, E. (1963). Org. Synth. 4, 339–342.
  • Elderfield, R. C. (1960). Heterocyclic Compounds, edited by R. C. Elderfield, Vol. 4, p. 1. New York, London: John Wiley.
  • 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.
  • Hatanaka, N. & Ojima, I. (1981). J. Chem. Soc. Chem. Commun. pp. 344–346.
  • Kournetsov, V. V., Mendez, L. Y. V. & Gomez, C. M. M. (2005). Curr. Org. Chem.9, 141–161.
  • Lyle, G. G. & Keefer, L. K. (1967). Tetrahedron, 23, 3253–3263.
  • Mouzine, G., Cousse, H. & Autin, J. M. (1980). Synthesis, p. 54.
  • Ohta, H., Kobayashi, N. & Ozaki, K. (1989). J. Org. Chem.54, 1802–1804.
  • Sahu, N. S., Pal, C., Mandal, N. B., Banerjee, S., Raha, M., Kundu, A. P., Basu, A., Ghosh, M., Roy, K. & Bandyopadhyay, S. (2002). Bioorg. Med. Chem.10, 1687–1693. [PubMed]
  • Sheldrick, G. M. (2002). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Smith, M. B. (1994). Editor. Organic Synthesis, p. 441. New York: Mc Graw-Hill.
  • Wright, C. W., Addac-Kyereme, J., Breen, A. G., Brown, J. E., Cox, M. F., Croft, S. L., Gokcek, Y., Kendrick, H., Phillips, R. M. & Pollet, P. L. (2001). J. Med. Chem.44, 3187–3194. [PubMed]

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