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Acta Crystallogr Sect E Struct Rep Online. 2008 April 1; 64(Pt 4): o763–o764.
Published online 2008 March 29. doi:  10.1107/S1600536808007885
PMCID: PMC2960955

6-Meth­oxy-2,3,4,9-tetra­hydro-1H-carbazol-1-one

Abstract

The carbazole unit of the title mol­ecule, C13H13NO2, is not planar. The dihedral angle between the benzene ring and the pyrrole ring is 1.69 (6)°. The cyclo­hexene ring adopts an envelope conformation. Inter­molecular C—H(...)O and N—H(...)O hydrogen bonds are present in the crystal structure. A C—H(...)π inter­action, involving the benzene ring, is also found in the crystal structure.

Related literature

For related literature, see: Bhattacharya & Chakraborty (1987 [triangle]); Chakraborty & Roy (1991 [triangle]); Chakraborty (1993 [triangle]); Knolker (1986 [triangle]); Lescot et al. (1986 [triangle]); Hook et al. (1990 [triangle]); Hirata et al. (1999 [triangle]); Kapil (1971 [triangle]); Knolker & Reddy (2002 [triangle]); Sowmithran & Rajendra Prasad (1986 [triangle]); Rajendra Prasad & Vijayalakshmi (1994 [triangle]). Gunaseelan et al. (2007a [triangle],b [triangle]) and Thiruvalluvar et al. (2007 [triangle]) have reported the crystal structures of substituted carbazole derivatives, in which the carbazole units are not planar.

An external file that holds a picture, illustration, etc.
Object name is e-64-0o763-scheme1.jpg

Experimental

Crystal data

  • C13H13NO2
  • M r = 215.24
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0o763-efi1.jpg
  • a = 9.0627 (2) Å
  • b = 14.0285 (3) Å
  • c = 8.5506 (2) Å
  • β = 101.815 (1)°
  • V = 1064.06 (4) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 160 (1) K
  • 0.35 × 0.28 × 0.13 mm

Data collection

  • Nonius KappaCCD area-detector diffractometer
  • Absorption correction: none
  • 28554 measured reflections
  • 3077 independent reflections
  • 2601 reflections with I > 2σ(I)
  • R int = 0.038

Refinement

  • R[F 2 > 2σ(F 2)] = 0.043
  • wR(F 2) = 0.145
  • S = 1.12
  • 3077 reflections
  • 149 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.33 e Å−3
  • Δρmin = −0.24 e Å−3

Data collection: COLLECT (Nonius, 2000 [triangle]); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 [triangle]); data reduction: DENZO-SMN and SCALEPACK (Otwinowski & Minor, 1997 [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 (Farrugia, 1997 [triangle]); software used to prepare material for publication: PLATON (Spek, 2003 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808007885/wn2245sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808007885/wn2245Isup2.hkl

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

Acknowledgments

KJR acknowledges the UGC, New Delhi, India, for the award of a Major Research Project grant F.No.31–122/2005. MS thanks the UGC, New Delhi for the award of a research fellowship.

supplementary crystallographic information

Comment

Heterocylic compounds are encountered in a very large number of groups of organic compounds. They play a vital role in the metabolism of all living cells, which are widely distributed in nature and are essential to life. Among them the carbazole heterocycles have emerged as an important class, based on their fascinating structure and high degree of biological activities (Bhattacharya & Chakraborty,1987; Chakraborty & Roy, 1991; Chakraborty, 1993). A number of carbazole alkaloids with intriguing novel structures and useful biological activities were isolated from natural sources over the past decades; these attracted chemists to frame novel synthetic strategies towards the synthesis of carbazole and its derivatives (Knolker,1986; Lescot et al., 1986). These alkaloids represent a new and interesting variant in the large number of indole alkaloids, which have yielded several important drugs. Several reports have appeared on the synthesis of carbazole derivatives, in connection with the search for newer physiologically active compounds (Hook et al., 1990; Hirata et al., 1999; Kapil, 1971; Knolker & Reddy, 2002). The preparation of 1-oxo compounds via their corresponding hydrazones have been reported (Sowmithran & Rajendra Prasad, 1986; Rajendra Prasad & Vijayalakshmi, 1994).

Gunaseelan et al. (2007a,b) and Thiruvalluvar et al. (2007) have reported the crystal structures of substituted carbazole derivatives, in which the carbazole units are not planar. The molecular structure of the title compound, with atomic numbering scheme, is shown in Fig. 1. The carbazole unit of the title molecule is not planar. The dihedral angle between the benzene ring and the pyrrole ring is 1.69 (6)°. The cyclohexene ring adopts an envelope conformation. Intermolecular C2—H2A···O2(x + 1, y, z + 1) and N9—H9···O1(-x + 1, -y + 1, -z + 1) hydrogen bonds are present in the crystal structure (Fig. 2). A C4—H4B···π(x, 3/2 - y,1/2 + z) interaction involving the benzene ring is also found in the structure, .

Experimental

A solution of 2-(2-(4-methoxyphenyl)hydrazono)cyclohexanone (232 mg, 0.001 mol) in a mixture of acetic acid (20 ml) and hydrochloric acid (5 ml) was refluxed on an oil bath pre-heated to 398-403 K for 2 h. The reaction was monitored by TLC. After completion of the reaction the contents were cooled and poured on to cold water with stirring. The brown solid which separated was purified by passing through a column of silica gel and eluting with a (95:5) petroleum ether-ethyl acetate mixture, yielding the title compound (144 mg, 67%). The compound thus obtained was recrystallized using ethanol.

Refinement

The H atom bonded to N9 was located in a difference Fourier map and refined isotropically. Other H atoms were positioned geometrically and allowed to ride on their parent atoms, with C—H = 0.95–0.99 Å and Uiso(H) = xUeq(parent atom), where x = 1.5 for methyl and 1.2 for all other carbon-bound H atoms.

Figures

Fig. 1.
The molecular structure of the title compound, showing the atom-numbering scheme and displacement ellipsoids drawn at the 50% probability level. Hydrogen atoms are represented by spheres of arbitrary radius.
Fig. 2.
The molecular packing of the title compound, viewed down the a axis. Dashed lines indicate hydrogen bonds. H atoms not involved in hydrogen bonding have been omitted.

Crystal data

C13H13NO2F000 = 456
Mr = 215.24Dx = 1.344 Mg m3
Monoclinic, P21/cMelting point: 536 K
Hall symbol: -P 2ybcMo Kα radiation λ = 0.71073 Å
a = 9.0627 (2) ÅCell parameters from 3175 reflections
b = 14.0285 (3) Åθ = 2.0–30.0º
c = 8.5506 (2) ŵ = 0.09 mm1
β = 101.815 (1)ºT = 160 (1) K
V = 1064.06 (4) Å3Tablet, colourless
Z = 40.35 × 0.28 × 0.13 mm

Data collection

Nonius KappaCCD area-detector diffractometer3077 independent reflections
Radiation source: Nonius FR590 sealed tube generator2601 reflections with I > 2σ(I)
Monochromator: horizontally mounted graphite crystalRint = 0.038
Detector resolution: 9 pixels mm-1θmax = 30.0º
T = 160(1) Kθmin = 2.3º
[var phi] and ω scans with κ offsetsh = −12→12
Absorption correction: nonek = 0→19
28554 measured reflectionsl = 0→12

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.043H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.146  w = 1/[σ2(Fo2) + (0.0825P)2 + 0.2332P] where P = (Fo2 + 2Fc2)/3
S = 1.12(Δ/σ)max < 0.001
3077 reflectionsΔρmax = 0.33 e Å3
149 parametersΔρmin = −0.24 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

Experimental. Solvent used: EtOH Cooling Device: Oxford Cryosystems Cryostream 700 Crystal mount: glued on a glass fibre Mosaicity (°.): 0.742 (2) Frames collected: 359 Seconds exposure per frame: 100 Degrees rotation per frame: 2.0 Crystal-Detector distance (mm): 30.0
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles
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
O10.53223 (10)0.52978 (7)0.72771 (11)0.0324 (3)
O2−0.29638 (10)0.67151 (8)0.18475 (11)0.0354 (3)
N90.27900 (11)0.55709 (7)0.45710 (11)0.0229 (3)
C10.41200 (13)0.56555 (8)0.74513 (13)0.0229 (3)
C20.38660 (13)0.59515 (9)0.90781 (13)0.0251 (3)
C30.27324 (13)0.67715 (8)0.90149 (13)0.0236 (3)
C40.12214 (12)0.65469 (8)0.79020 (12)0.0213 (3)
C4A0.14868 (12)0.61976 (7)0.63321 (12)0.0196 (3)
C4B0.05307 (12)0.61980 (7)0.47874 (13)0.0197 (3)
C5−0.09638 (12)0.65107 (8)0.42156 (13)0.0219 (3)
C6−0.15394 (12)0.64344 (8)0.25953 (13)0.0241 (3)
C7−0.06690 (13)0.60611 (8)0.15394 (13)0.0253 (3)
C80.07867 (13)0.57456 (8)0.20802 (13)0.0236 (3)
C8A0.13856 (12)0.58090 (7)0.37241 (13)0.0208 (3)
C9A0.28448 (12)0.58046 (8)0.61527 (13)0.0213 (3)
C16−0.38951 (15)0.71146 (13)0.28342 (18)0.0441 (5)
H2A0.484200.614840.974910.0301*
H2B0.349780.539390.959630.0301*
H3A0.256280.689461.010440.0283*
H3B0.316070.735720.863900.0283*
H4A0.068030.605390.839380.0256*
H4B0.058820.712780.773730.0256*
H5−0.155090.676410.491920.0262*
H7−0.109880.602720.043000.0303*
H80.136330.549420.136480.0284*
H90.3587 (19)0.5296 (12)0.416 (2)0.038 (4)*
H16A−0.487420.728860.217420.0661*
H16B−0.340890.768450.336970.0661*
H16C−0.404280.664540.363740.0661*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0269 (5)0.0436 (5)0.0274 (4)0.0137 (4)0.0075 (3)−0.0016 (4)
O20.0230 (4)0.0513 (6)0.0293 (5)0.0061 (4)−0.0008 (3)−0.0103 (4)
N90.0239 (5)0.0262 (5)0.0202 (4)0.0049 (3)0.0084 (3)−0.0009 (3)
C10.0245 (5)0.0232 (5)0.0222 (5)0.0045 (4)0.0076 (4)0.0004 (4)
C20.0249 (5)0.0302 (6)0.0205 (5)0.0067 (4)0.0054 (4)−0.0010 (4)
C30.0235 (5)0.0252 (5)0.0227 (5)0.0028 (4)0.0064 (4)−0.0045 (4)
C40.0224 (5)0.0233 (5)0.0196 (5)0.0030 (4)0.0073 (4)−0.0010 (4)
C4A0.0215 (5)0.0188 (5)0.0199 (5)0.0012 (3)0.0073 (4)0.0012 (3)
C4B0.0215 (5)0.0182 (5)0.0205 (5)−0.0004 (4)0.0071 (4)−0.0004 (3)
C50.0212 (5)0.0223 (5)0.0232 (5)−0.0014 (4)0.0071 (4)−0.0022 (4)
C60.0208 (5)0.0260 (5)0.0249 (5)−0.0018 (4)0.0036 (4)−0.0033 (4)
C70.0274 (6)0.0272 (5)0.0211 (5)−0.0025 (4)0.0045 (4)−0.0034 (4)
C80.0276 (5)0.0245 (5)0.0204 (5)−0.0009 (4)0.0089 (4)−0.0025 (4)
C8A0.0231 (5)0.0200 (5)0.0210 (5)0.0001 (4)0.0085 (4)−0.0005 (3)
C9A0.0232 (5)0.0222 (5)0.0197 (5)0.0030 (4)0.0073 (4)0.0002 (4)
C160.0261 (6)0.0610 (10)0.0421 (8)0.0118 (6)0.0000 (5)−0.0185 (7)

Geometric parameters (Å, °)

O1—C11.2360 (15)C6—C71.4154 (16)
O2—C61.3756 (15)C7—C81.3785 (17)
O2—C161.4247 (18)C8—C8A1.4021 (15)
N9—C8A1.3706 (15)C2—H2A0.9900
N9—C9A1.3826 (14)C2—H2B0.9900
N9—H90.948 (17)C3—H3A0.9900
C1—C9A1.4446 (16)C3—H3B0.9900
C1—C21.5138 (16)C4—H4A0.9900
C2—C31.5359 (17)C4—H4B0.9900
C3—C41.5318 (16)C5—H50.9500
C4—C4A1.4940 (14)C7—H70.9500
C4A—C4B1.4236 (15)C8—H80.9500
C4A—C9A1.3854 (16)C16—H16A0.9800
C4B—C8A1.4189 (15)C16—H16B0.9800
C4B—C51.4124 (16)C16—H16C0.9800
C5—C61.3810 (15)
O1···N92.9314 (13)C16···H3Bviii2.9800
O1···N9i2.8313 (14)H2A···O2x2.5200
O1···H92.804 (17)H2A···C16x2.9800
O1···H2Bii2.8400H2A···H16Ax2.5900
O1···H9i1.918 (17)H2B···O1ii2.8400
O2···H2Aiii2.5200H2B···C2ii3.0700
N9···O12.9314 (13)H3A···C8xi3.0300
N9···O1i2.8313 (14)H3A···H8xi2.5900
C1···C16iv3.590 (2)H3B···C9A3.0200
C2···C2ii3.5370 (17)H3B···C8Av3.0400
C3···C8Av3.5983 (15)H3B···C16iv2.9800
C4B···C4Bvi3.5353 (14)H3B···H16Aiv2.4300
C6···C9Avi3.5958 (16)H4A···C7vi2.9700
C8A···C3vii3.5983 (15)H4A···C8vi2.8400
C9A···C6vi3.5958 (16)H4B···C4Bv2.9400
C16···C1viii3.590 (2)H4B···C5v2.8200
C1···H16Aiv3.0500H4B···C6v2.7800
C1···H9i3.028 (17)H4B···C7v2.8900
C2···H2Bii3.0700H4B···C8v3.0500
C4B···H4Bvii2.9400H4B···C8Av3.0600
C5···H16C2.7400H5···C162.5300
C5···H4Bvii2.8200H5···H16B2.3100
C5···H16B2.7400H5···H16C2.3100
C6···H4Bvii2.7800H8···H3Aix2.5900
C7···H4Bvii2.8900H9···O12.804 (17)
C7···H4Avi2.9700H9···O1i1.918 (17)
C8···H4Bvii3.0500H9···C1i3.028 (17)
C8···H4Avi2.8400H16A···H2Aiii2.5900
C8···H3Aix3.0300H16A···C1viii3.0500
C8A···H4Bvii3.0600H16A···H3Bviii2.4300
C8A···H3Bvii3.0400H16B···C52.7400
C9A···H3B3.0200H16B···H52.3100
C16···H2Aiii2.9800H16C···C52.7400
C16···H52.5300H16C···H52.3100
C6—O2—C16116.79 (10)C1—C2—H2A109.00
C8A—N9—C9A107.61 (9)C1—C2—H2B109.00
C9A—N9—H9125.6 (10)C3—C2—H2A109.00
C8A—N9—H9126.8 (10)C3—C2—H2B109.00
O1—C1—C9A123.53 (10)H2A—C2—H2B108.00
O1—C1—C2121.72 (10)C2—C3—H3A109.00
C2—C1—C9A114.73 (10)C2—C3—H3B109.00
C1—C2—C3113.55 (9)C4—C3—H3A109.00
C2—C3—C4111.98 (9)C4—C3—H3B109.00
C3—C4—C4A109.74 (9)H3A—C3—H3B108.00
C4B—C4A—C9A106.45 (9)C3—C4—H4A110.00
C4—C4A—C4B130.85 (10)C3—C4—H4B110.00
C4—C4A—C9A122.69 (10)C4A—C4—H4A110.00
C5—C4B—C8A120.56 (10)C4A—C4—H4B110.00
C4A—C4B—C8A106.61 (9)H4A—C4—H4B108.00
C4A—C4B—C5132.82 (10)C4B—C5—H5121.00
C4B—C5—C6117.50 (10)C6—C5—H5121.00
O2—C6—C5124.74 (10)C6—C7—H7119.00
O2—C6—C7113.70 (10)C8—C7—H7119.00
C5—C6—C7121.55 (10)C7—C8—H8121.00
C6—C7—C8121.66 (10)C8A—C8—H8121.00
C7—C8—C8A117.60 (10)O2—C16—H16A109.00
N9—C8A—C8129.88 (10)O2—C16—H16B109.00
C4B—C8A—C8121.11 (10)O2—C16—H16C109.00
N9—C8A—C4B108.97 (9)H16A—C16—H16B109.00
C1—C9A—C4A124.16 (10)H16A—C16—H16C109.00
N9—C9A—C1125.48 (10)H16B—C16—H16C109.00
N9—C9A—C4A110.36 (10)
C16—O2—C6—C50.21 (18)C4B—C4A—C9A—N90.74 (12)
C16—O2—C6—C7−178.89 (12)C9A—C4A—C4B—C8A−0.84 (11)
C9A—N9—C8A—C8177.52 (11)C4—C4A—C9A—N9−178.17 (10)
C8A—N9—C9A—C4A−0.35 (12)C4—C4A—C4B—C8A177.95 (10)
C9A—N9—C8A—C4B−0.20 (12)C9A—C4A—C4B—C5−179.48 (11)
C8A—N9—C9A—C1179.00 (10)C5—C4B—C8A—N9179.49 (10)
C9A—C1—C2—C3−29.21 (14)C4A—C4B—C8A—N90.65 (12)
O1—C1—C2—C3152.17 (11)C5—C4B—C8A—C81.54 (16)
C2—C1—C9A—N9−178.39 (11)C4A—C4B—C5—C6177.60 (11)
C2—C1—C9A—C4A0.87 (16)C8A—C4B—C5—C6−0.89 (16)
O1—C1—C9A—C4A179.47 (11)C4A—C4B—C8A—C8−177.31 (10)
O1—C1—C9A—N90.21 (19)C4B—C5—C6—O2−179.27 (11)
C1—C2—C3—C454.63 (13)C4B—C5—C6—C7−0.24 (16)
C2—C3—C4—C4A−49.23 (12)O2—C6—C7—C8179.92 (11)
C3—C4—C4A—C4B−156.37 (11)C5—C6—C7—C80.80 (18)
C3—C4—C4A—C9A22.25 (14)C6—C7—C8—C8A−0.17 (17)
C4—C4A—C4B—C5−0.7 (2)C7—C8—C8A—N9−178.45 (11)
C4B—C4A—C9A—C1−178.62 (10)C7—C8—C8A—C4B−0.97 (16)
C4—C4A—C9A—C12.47 (17)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y+1, −z+2; (iii) x−1, y, z−1; (iv) x+1, −y+3/2, z+1/2; (v) x, −y+3/2, z+1/2; (vi) −x, −y+1, −z+1; (vii) x, −y+3/2, z−1/2; (viii) x−1, −y+3/2, z−1/2; (ix) x, y, z−1; (x) x+1, y, z+1; (xi) x, y, z+1.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N9—H9···O1i0.948 (17)1.918 (17)2.8313 (14)161.2 (15)
C2—H2A···O2x0.992.523.4962 (15)169
C4—H4B···Cgv0.992.573.492 (1)156

Symmetry codes: (i) −x+1, −y+1, −z+1; (x) x+1, y, z+1; (v) x, −y+3/2, z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WN2245).

References

  • Bhattacharya, P. & Chakraborty, D. P. (1987). Progress in the Chemistry of Organic Natural Products, Vol. 52, edited by W. Herz, H. Grisebach, G. W. Kirby & C. Tamm, pp. 299–371. Wien: Springer Verlag.
  • Chakraborty, D. P. (1993). The Alkaloids, Vol. 44, edited by A. Brossi, pp. 257–282. New York: Academic Press.
  • Chakraborty, D. P. & Roy, S. (1991). Progress in the Chemistry of Organic Natural Products Vol. 57, edited by W. Herz, H. Grisebach, G. W. Kirby & C. Tamm, pp. 71–110. Wien: Springer Verlag.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Gunaseelan, A. T., Thiruvalluvar, A., Martin, A. E. & Prasad, K. J. R. (2007a). Acta Cryst. E63, o2413–o2414.
  • Gunaseelan, A. T., Thiruvalluvar, A., Martin, A. E. & Prasad, K. J. R. (2007b). Acta Cryst. E63, o2729–o2730.
  • Hirata, K., Ito, C., Furukawa, H., Itoigawa, M., Cosentino, L. M. & Lee, K. H. (1999). Bioorg. Med. Chem. Lett.9, 119–122. [PubMed]
  • Hook, D. J., Yacobucci, J. J., O’Connor, S., Lee, M., Kerns, E., Krishnan, B., Matson, J. & Hesler, G. J. (1990). Antibiot.43, 1347–1348. [PubMed]
  • Kapil, R. S. (1971). The Alkaloids, Vol. 13, edited by R. H. F. Manske, p. 273. New York: Academic Press.
  • Knolker, H. J. (1986). Advances in Nitrogen Heterocycles, Vol. 1, edited by C. J. Moody, p. 273. Geenwich, Connecticut: JAI Press.
  • Knolker, H. J. & Reddy, K. R. (2002). Chem. Rev.102, 4303–4427. [PubMed]
  • Lescot, E., Muzard, G., Markovits, J., Belleney, J., Roques, B. P. & Le Pecq, J. B. (1986). J. Med. Chem.29, 1731–1737. [PubMed]
  • Nonius (2000). COLLECT Nonius BV, Delft, The Netherlands.
  • Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter & R. M. Sweet, pp. 307–326. London: Academic Press.
  • Rajendra Prasad, K. J. & Vijayalakshmi, C. S. (1994). Indian J. Chem.33B, 481–482.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Sowmithran, D. & Rajendra Prasad, K. J. (1986). Heterocycles, 24, 711–717.
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.
  • Thiruvalluvar, A., Gunaseelan, A. T., Martin, A. E., Prasad, K. J. R. & Butcher, R. J. (2007). Acta Cryst. E63, o3524.

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