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Acta Crystallogr Sect E Struct Rep Online. 2008 August 1; 64(Pt 8): o1418.
Published online 2008 July 5. doi:  10.1107/S1600536808020047
PMCID: PMC2961900

(E)-6-Meth­oxy-9-methyl-1,2,3,4-tetra­hydro-9H-carbazol-4-one oxime

Abstract

The title compound, C14H16N2O2, is dimerized by inversion-related inter­molecular O—H(...)O and O—H(...)N hydrogen bonding. There is also an intra­molecular C—H(...)N bond, resulting in a six-membered ring.

Related literature

For general background, see: Hester (1967 [triangle], 1970 [triangle]). For related literature, see: Sheng et al. (2008 [triangle]).

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Object name is e-64-o1418-scheme1.jpg

Experimental

Crystal data

  • C14H16N2O2
  • M r = 244.29
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1418-efi1.jpg
  • a = 8.833 (5) Å
  • b = 6.460 (4) Å
  • c = 22.247 (12) Å
  • β = 104.14 (2)°
  • V = 1231.0 (12) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 293 (2) K
  • 0.15 × 0.08 × 0.08 mm

Data collection

  • Bruker SMART APEX CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.987, T max = 0.993
  • 5647 measured reflections
  • 2626 independent reflections
  • 1396 reflections with I > 2σ(I)
  • R int = 0.037

Refinement

  • R[F 2 > 2σ(F 2)] = 0.055
  • wR(F 2) = 0.165
  • S = 0.89
  • 2626 reflections
  • 169 parameters
  • 2 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.61 e Å−3
  • Δρmin = −0.32 e Å−3

Data collection: SMART (Bruker, 2000 [triangle]); cell refinement: SMART; data reduction: SAINT (Bruker, 2000 [triangle]); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL and ORTEP-3 (Farrugia, 1997 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808020047/om2245sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808020047/om2245Isup2.hkl

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

Acknowledgments

This work is funded in part by the National Natural Science Foundation of China (grant No. 30472088).

supplementary crystallographic information

Comment

The most famous of the rearrangements in which R migrates from carbon to nitrogen is undoubtedly the conversion of ketoximes to N-subsituted amides, the Beckmann rearrangement. The most interesting feature of the rearrangement is that, it is not the nature (e.g. relative electron-releasing ability)but the stereochemical arrangment of the R and R'groups that determines which of them migrates. Almost without exception it is found to be the R group anti to the OH group that migrates from C to N. Thus, the structure of the amide produced is quite often used to establish the configuration of the oxime from which it was derived.

Surprisingly, in our study we obtained two different amides from one oxime by applying two different Beckmann conditions. This particular oxime, 6-methoxy -9-methyl-1,2,3,9-tetrahydro-4H-carbazol-4-one oxime (I), is found to yield only 6-methyl-9-methoxy-2,3,4,5-tetrahydroazepino[4,3-b]indol- 1(6H)-one (II) while treated with polyphophoric acids. However, by converting the OH group of (I) into a better leaving tosyl group followed a catalysis using Al2O3, (I) undergoes the rearrangement to 6-methyl-9- methoxy-3,4,5,6-tetrahydroazepino[3,2-b]indol-2(1H)-one (III) exclusively. Here we report the crystal structure of (I) in order to get a better understanding of the mechanism of this peculiar process.

Fig.1. shows the molecular structure of the title compound (I), which is almost planar and has the (E)-configuration. As shown in Fig. 2, the title compound is dimerized by inversion of (E)-6-methoxy-9-methyl-1,2,3,9-tetrahydro-4H-carbazol-4-one oxime through intermolecular H-bond viz O1—H1X···O1i and O1—H1X···N1i[symmetry code i = -x + 1,-y,-z]. There is also an intramolecular hydrogen bond of C5—H5···N1 resulting in a six-membered ring.

Experimental

The title compound (I) was prepared in three steps as follows. Firstly, with use of a method described by Sheng et al. (2008), 6-Methoxy-1,2,3,9- tetrahydro-4H-carbazol-4-one (IV) was prepared as starting material. Then,(IV) was methylated using dimethyl sulfate in a mixed solution of acetone and NaOH aq. to give 6-methoxy-9-methyl-1,2,3,9-tetrahydro-4H-carbazol-4-one (V). A mixture of (V) and hydroxylamine hydrochloride was dissolved in methanol and the solution was refluxed with a catalytic amount of pyridine. The crude product of the title compound was recrystallized in acetone to afford colorless prismatic crystals suitable for X-ray analysis.

Refinement

The H atoms bonded to N and O in the carbazolone oxime were located in a difference map and refined with distance restraints of O—H = 0.82 (2) and N—H = 0.89 (2) Å. The H atoms attached to O and all carbon-bound H atoms were placed in calculated positions and refined as riding; O—H=0.82 and C—H=0.93–0.98 Å;Uiso(H) = xUeq(parent atom) where x=1.5 for O and 1.2 for C.

Figures

Fig. 1.
The molecular structure of the title compound, showing ellipsoids at the 20% probability level.
Fig. 2.
A view of the crystal packing, showing the hydrogen-bonding network.

Crystal data

C14H16N2O2F000 = 520
Mr = 244.29Dx = 1.318 Mg m3
Monoclinic, P21/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 777 reflections
a = 8.833 (5) Åθ = 2.4–22.7º
b = 6.460 (4) ŵ = 0.09 mm1
c = 22.247 (12) ÅT = 293 (2) K
β = 104.14 (2)ºPrism, colorless
V = 1231.0 (12) Å30.15 × 0.08 × 0.08 mm
Z = 4

Data collection

Bruker SMART APEX CCD area-detector diffractometer2626 independent reflections
Radiation source: fine-focus sealed tube1396 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.037
T = 293(2) Kθmax = 27.0º
[var phi] and ω scansθmin = 1.9º
Absorption correction: multi-scan(SADABS; Sheldrick, 1996)h = −11→11
Tmin = 0.987, Tmax = 0.993k = −8→8
5647 measured reflectionsl = −27→17

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.055H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.165  w = 1/[σ2(Fo2) + (0.0985P)2] where P = (Fo2 + 2Fc2)/3
S = 0.89(Δ/σ)max < 0.001
2626 reflectionsΔρmax = 0.61 e Å3
169 parametersΔρmin = −0.32 e Å3
2 restraintsExtinction correction: none
Primary atom site location: structure-invariant direct methods

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
O10.3608 (3)−0.1623 (4)−0.01619 (11)0.0908 (7)
H1X0.392 (4)−0.054 (4)0.0026 (18)0.127 (16)*
O21.0030 (2)0.1510 (3)−0.09437 (10)0.0781 (6)
N10.4790 (2)−0.1762 (4)−0.04926 (10)0.0618 (6)
C10.4333 (3)−0.7039 (4)−0.16677 (13)0.0631 (7)
H1A0.4711−0.8230−0.14090.076*
H1B0.4036−0.7496−0.20960.076*
C20.2945 (4)−0.6123 (6)−0.14878 (16)0.0868 (10)
H2A0.2228−0.7231−0.14550.104*
H2B0.2410−0.5203−0.18160.104*
C30.3335 (3)−0.4929 (5)−0.08831 (13)0.0656 (7)
H3A0.2402−0.4226−0.08340.079*
H3B0.3647−0.5901−0.05430.079*
C40.4606 (2)−0.3367 (4)−0.08413 (11)0.0485 (6)
C4'0.5725 (2)−0.3745 (3)−0.12087 (9)0.0422 (5)
C5'0.7093 (2)−0.2625 (3)−0.12699 (9)0.0407 (5)
C50.7843 (2)−0.0819 (4)−0.10084 (10)0.0445 (5)
H50.7437−0.0036−0.07340.053*
C60.9189 (3)−0.0218 (4)−0.11637 (11)0.0511 (6)
C70.9790 (3)−0.1381 (4)−0.15859 (12)0.0587 (7)
H71.0704−0.0947−0.16850.070*
C80.9066 (3)−0.3127 (4)−0.18535 (11)0.0536 (6)
H80.9468−0.3879−0.21360.064*
C8'0.7708 (2)−0.3758 (4)−0.16943 (9)0.0441 (5)
C90.7019 (3)−0.6996 (4)−0.23323 (12)0.0674 (8)
H9A0.6501−0.8262−0.22770.101*
H9B0.8117−0.7251−0.22730.101*
H9C0.6599−0.6479−0.27440.101*
N90.6779 (2)−0.5471 (3)−0.18818 (8)0.0499 (5)
C9'0.5588 (3)−0.5450 (4)−0.15895 (10)0.0477 (6)
C100.9545 (3)0.2735 (4)−0.04983 (13)0.0669 (7)
H10A0.85140.3259−0.06730.100*
H10B1.02540.3872−0.03790.100*
H10C0.95360.1907−0.01410.100*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0865 (15)0.1012 (18)0.1098 (17)−0.0189 (14)0.0724 (14)−0.0310 (15)
O20.0703 (12)0.0740 (13)0.1042 (15)−0.0285 (10)0.0485 (11)−0.0276 (11)
N10.0588 (13)0.0686 (15)0.0708 (14)−0.0054 (11)0.0408 (11)−0.0104 (12)
C10.0635 (15)0.0564 (16)0.0647 (16)−0.0101 (13)0.0067 (13)−0.0052 (13)
C20.0733 (18)0.091 (2)0.101 (2)−0.0302 (17)0.0300 (17)−0.0095 (18)
C30.0569 (15)0.0730 (19)0.0708 (17)−0.0128 (14)0.0233 (13)0.0026 (14)
C40.0447 (12)0.0537 (15)0.0499 (13)0.0003 (11)0.0167 (10)0.0059 (12)
C4'0.0406 (11)0.0448 (13)0.0413 (12)0.0003 (10)0.0104 (9)0.0019 (10)
C5'0.0384 (11)0.0489 (13)0.0354 (11)0.0046 (10)0.0100 (9)0.0029 (10)
C50.0441 (12)0.0484 (14)0.0448 (12)−0.0004 (10)0.0185 (10)−0.0026 (10)
C60.0472 (12)0.0525 (15)0.0574 (14)−0.0061 (11)0.0198 (11)−0.0045 (12)
C70.0480 (13)0.0679 (18)0.0688 (16)−0.0044 (13)0.0311 (12)−0.0021 (14)
C80.0530 (13)0.0642 (17)0.0496 (13)0.0078 (12)0.0243 (11)−0.0033 (12)
C8'0.0434 (12)0.0499 (14)0.0391 (11)0.0055 (10)0.0102 (9)−0.0019 (10)
C90.0851 (19)0.0615 (17)0.0577 (15)0.0048 (14)0.0216 (14)−0.0169 (13)
N90.0531 (11)0.0521 (12)0.0450 (11)0.0026 (10)0.0132 (9)−0.0093 (9)
C9'0.0473 (12)0.0495 (14)0.0444 (12)0.0018 (11)0.0074 (10)0.0019 (11)
C100.0744 (17)0.0602 (17)0.0676 (17)−0.0170 (14)0.0204 (14)−0.0140 (14)

Geometric parameters (Å, °)

O1—N11.419 (3)C5'—C51.397 (3)
O1—H1X0.827 (18)C5'—C8'1.405 (3)
O2—C61.364 (3)C5—C61.373 (3)
O2—C101.414 (3)C5—H50.9300
N1—C41.281 (3)C6—C71.404 (3)
C1—C9'1.489 (3)C7—C81.360 (3)
C1—C21.502 (4)C7—H70.9300
C1—H1A0.9700C8—C8'1.392 (3)
C1—H1B0.9700C8—H80.9300
C2—C31.516 (4)C8'—N91.380 (3)
C2—H2A0.9700C9—N91.457 (3)
C2—H2B0.9700C9—H9A0.9599
C3—C41.495 (3)C9—H9B0.9599
C3—H3A0.9700C9—H9C0.9599
C3—H3B0.9700N9—C9'1.365 (3)
C4—C4'1.449 (3)C10—H10A0.9599
C4'—C9'1.377 (3)C10—H10B0.9599
C4'—C5'1.443 (3)C10—H10C0.9599
N1—O1—H1X97 (3)C5'—C5—H5120.6
C6—O2—C10118.53 (19)O2—C6—C5124.8 (2)
C4—N1—O1111.4 (2)O2—C6—C7114.6 (2)
C9'—C1—C2109.3 (2)C5—C6—C7120.6 (2)
C9'—C1—H1A109.8C8—C7—C6121.5 (2)
C2—C1—H1A109.8C8—C7—H7119.3
C9'—C1—H1B109.8C6—C7—H7119.3
C2—C1—H1B109.8C7—C8—C8'118.3 (2)
H1A—C1—H1B108.3C7—C8—H8120.9
C1—C2—C3114.4 (3)C8'—C8—H8120.9
C1—C2—H2A108.7N9—C8'—C8130.1 (2)
C3—C2—H2A108.7N9—C8'—C5'108.78 (19)
C1—C2—H2B108.7C8—C8'—C5'121.1 (2)
C3—C2—H2B108.7N9—C9—H9A109.5
H2A—C2—H2B107.6N9—C9—H9B109.5
C4—C3—C2113.8 (2)H9A—C9—H9B109.5
C4—C3—H3A108.8N9—C9—H9C109.5
C2—C3—H3A108.8H9A—C9—H9C109.5
C4—C3—H3B108.8H9B—C9—H9C109.5
C2—C3—H3B108.8C9'—N9—C8'108.57 (17)
H3A—C3—H3B107.7C9'—N9—C9126.4 (2)
N1—C4—C4'118.3 (2)C8'—N9—C9125.0 (2)
N1—C4—C3124.5 (2)N9—C9'—C4'109.8 (2)
C4'—C4—C3117.2 (2)N9—C9'—C1125.1 (2)
C9'—C4'—C5'107.03 (19)C4'—C9'—C1125.0 (2)
C9'—C4'—C4120.8 (2)O2—C10—H10A109.5
C5'—C4'—C4132.2 (2)O2—C10—H10B109.5
C5—C5'—C8'119.57 (19)H10A—C10—H10B109.5
C5—C5'—C4'134.6 (2)O2—C10—H10C109.5
C8'—C5'—C4'105.8 (2)H10A—C10—H10C109.5
C6—C5—C5'118.9 (2)H10B—C10—H10C109.5
C6—C5—H5120.6
C9'—C1—C2—C3−46.4 (3)C6—C7—C8—C8'−0.6 (4)
C1—C2—C3—C450.2 (4)C7—C8—C8'—N9−178.2 (2)
O1—N1—C4—C4'−179.6 (2)C7—C8—C8'—C5'0.2 (3)
O1—N1—C4—C3−1.5 (4)C5—C5'—C8'—N9179.49 (18)
C2—C3—C4—N1155.9 (3)C4'—C5'—C8'—N9−0.1 (2)
C2—C3—C4—C4'−26.0 (3)C5—C5'—C8'—C80.8 (3)
N1—C4—C4'—C9'179.7 (2)C4'—C5'—C8'—C8−178.8 (2)
C3—C4—C4'—C9'1.5 (3)C8—C8'—N9—C9'178.7 (2)
N1—C4—C4'—C5'0.0 (4)C5'—C8'—N9—C9'0.2 (2)
C3—C4—C4'—C5'−178.2 (2)C8—C8'—N9—C9−3.0 (4)
C9'—C4'—C5'—C5−179.6 (2)C5'—C8'—N9—C9178.4 (2)
C4—C4'—C5'—C50.2 (4)C8'—N9—C9'—C4'−0.3 (2)
C9'—C4'—C5'—C8'0.0 (2)C9—N9—C9'—C4'−178.4 (2)
C4—C4'—C5'—C8'179.7 (2)C8'—N9—C9'—C1−179.9 (2)
C8'—C5'—C5—C6−1.4 (3)C9—N9—C9'—C11.9 (4)
C4'—C5'—C5—C6178.1 (2)C5'—C4'—C9'—N90.2 (2)
C10—O2—C6—C53.4 (4)C4—C4'—C9'—N9−179.64 (19)
C10—O2—C6—C7−177.7 (2)C5'—C4'—C9'—C1179.9 (2)
C5'—C5—C6—O2179.8 (2)C4—C4'—C9'—C10.0 (3)
C5'—C5—C6—C71.0 (3)C2—C1—C9'—N9−157.9 (2)
O2—C6—C7—C8−178.9 (2)C2—C1—C9'—C4'22.4 (3)
C5—C6—C7—C80.0 (4)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C5—H5···N10.932.763.236 (3)113
O1—H1X···O1i0.827 (18)2.54 (3)3.177 (5)134 (3)
O1—H1X···N1i0.827 (18)2.00 (2)2.810 (4)166 (4)

Symmetry codes: (i) −x+1, −y, −z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: OM2245).

References

  • Bruker (2000). SMART and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Hester, J. B. Jr (1967). J. Org. Chem.32, 3804–3808.
  • Hester, J. B. Jr (1970). J. Org. Chem.35, 875–883.
  • Sheldrick, G. M. (1996). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Sheng, W., Zheng, Y. L., Zhang, Q. H. & Qiu, Z. B. (2008). Chin. J. Pharm. 39, 330–331.

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