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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 64| Part 8| August 2008| Page o1418
doi:10.1107/S1600536808020047

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

Wei Sheng,a Qi-Hong Zhanga and Zhui-Bai Qiua*

aDepartment of Medicinal Chemistry, School of Pharmacy, Fudan University, 138 Yixueyuan Road, Shanghai 200032, People's Republic of China
*Correspondence e-mail: zbqiu@shmu.edu.cn

(Received 21 June 2008; accepted 1 July 2008; online 5 July 2008)

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[Hester, J. B. Jr (1967). J. Org. Chem. 32, 3804-3808.], 1970[Hester, J. B. Jr (1970). J. Org. Chem. 35, 875-883.]). For related literature, see: Sheng et al. (2008[Sheng, W., Zheng, Y. L., Zhang, Q. H. & Qiu, Z. B. (2008). Chin. J. Pharm. 39, 330-331.]).

[Scheme 1]

Experimental

Crystal data

  • C14H16N2O2

  • Mr = 244.29

  • Monoclinic, P 21 /c

  • 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[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.987, Tmax = 0.993

  • 5647 measured reflections

  • 2626 independent reflections

  • 1396 reflections with I > 2σ(I)

  • Rint = 0.037
Refinement

  • R[F2 > 2σ(F2)] = 0.055

  • wR(F2) = 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

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
C5—H5⋯N1 0.93 2.76 3.236 (3) 113
O1—H1X⋯O1i 0.827 (18) 2.54 (3) 3.177 (5) 134 (3)
O1—H1X⋯N1i 0.827 (18) 2.00 (2) 2.810 (4) 166 (4)
Symmetry code: (i) -x+1, -y, -z.

Data collection: SMART (Bruker, 2000[Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SMART; data reduction: SAINT (Bruker, 2000[Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL and ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXTL.

Supporting information

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

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

checkCIF report


Comment top

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.

Related literature top

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

Experimental top

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 top

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.

Computing details top

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

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing ellipsoids at the 20% probability level.
[Figure 2] Fig. 2. A view of the crystal packing, showing the hydrogen-bonding network.
(E)-6-Methoxy-9-methyl-1,2,3,4-tetrahydro-9H-carbazol-4-one oxime top
Crystal data top
C14H16N2O2F(000) = 520
Mr = 244.29Dx = 1.318 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 777 reflections
a = 8.833 (5) Åθ = 2.4–22.7°
b = 6.460 (4) ŵ = 0.09 mm−1
c = 22.247 (12) ÅT = 293 K
β = 104.14 (2)°Prism, colorless
V = 1231.0 (12) Å30.15 × 0.08 × 0.08 mm
Z = 4
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer		2626 independent reflections
Radiation source: fine-focus sealed tube1396 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.037
ϕ and ω scansθmax = 27.0°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −11→11
Tmin = 0.987, Tmax = 0.993k = −8→8
5647 measured reflectionsl = −27→17
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.055Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.165H atoms treated by a mixture of independent and constrained refinement
S = 0.89 w = 1/[σ2(Fo2) + (0.0985P)2]
where P = (Fo2 + 2Fc2)/3
2626 reflections(Δ/σ)max < 0.001
169 parametersΔρmax = 0.61 e Å−3
2 restraintsΔρmin = −0.32 e Å−3
Crystal data top
C14H16N2O2V = 1231.0 (12) Å3
Mr = 244.29Z = 4
Monoclinic, P21/cMo Kα radiation
a = 8.833 (5) ŵ = 0.09 mm−1
b = 6.460 (4) ÅT = 293 K
c = 22.247 (12) Å0.15 × 0.08 × 0.08 mm
β = 104.14 (2)°
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer		2626 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		1396 reflections with I > 2σ(I)
Tmin = 0.987, Tmax = 0.993Rint = 0.037
5647 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0552 restraints
wR(F2) = 0.165H atoms treated by a mixture of independent and constrained refinement
S = 0.89Δρmax = 0.61 e Å−3
2626 reflectionsΔρmin = −0.32 e Å−3
169 parameters
Special details top

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) top
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) top
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, º) top
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, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···N10.932.763.236 (3)113
O1—H1X···O1i0.83 (2)2.54 (3)3.177 (5)134 (3)
O1—H1X···N1i0.83 (2)2.00 (2)2.810 (4)166 (4)
Symmetry code: (i) −x+1, −y, −z.

Experimental details

Crystal data
Chemical formulaC14H16N2O2
Mr244.29
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)8.833 (5), 6.460 (4), 22.247 (12)
β (°) 104.14 (2)
V (Å3)1231.0 (12)
Z4
Radiation typeMo Kα
µ (mm−1)0.09
Crystal size (mm)0.15 × 0.08 × 0.08
Data collection
DiffractometerBruker SMART APEX CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.987, 0.993
No. of measured, independent and
observed [I > 2σ(I)] reflections		5647, 2626, 1396
Rint0.037
(sin θ/λ)max (Å−1)0.639
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.055, 0.165, 0.89
No. of reflections2626
No. of parameters169
No. of restraints2
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)0.61, −0.32

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXTL (Sheldrick, 2008) and ORTEP-3 (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···N10.932.763.236 (3)112.9
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 code: (i) −x+1, −y, −z.
 

Acknowledgements

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

References

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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

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ISSN: 2056-9890
Volume 64| Part 8| August 2008| Page o1418
doi:10.1107/S1600536808020047
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