PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2008 March 1; 64(Pt 3): o602.
Published online 2008 February 15. doi:  10.1107/S1600536808004376
PMCID: PMC2960885

(Z)-Methyl 2-methoxy­imino-3-oxo­butanoate

Abstract

The title compound, C6H9NO4, was prepared stereoselectively as a precursor for 1-aza­dienes in a study of hetero-Diels–Alder reactions. The configuration of the C=N double bond was found to be Z, corroborating earlier assignments of similar compounds based only on NMR and IR spectroscopic analysis.

Related literature

For related literature, see: Buehler (1967 [triangle]); Corrêa & Moran (1999 [triangle]); Fletcher et al. (2006 [triangle]); François et al. (2004 [triangle]); Jirman et al. (1990 [triangle]); Karabatsos & Taller (1968 [triangle]); Levy & Nelson (1972 [triangle]); Lu & Arndt (2007 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-0o602-scheme1.jpg

Experimental

Crystal data

  • C6H9NO4
  • M r = 159.14
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-64-0o602-efi1.jpg
  • a = 8.3410 (17) Å
  • b = 13.410 (3) Å
  • c = 7.2900 (15) Å
  • V = 815.4 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.11 mm−1
  • T = 291 (1) K
  • 0.2 × 0.2 × 0.2 mm

Data collection

  • Nonius KappaCCD diffractometer
  • Absorption correction: none
  • 3104 measured reflections
  • 899 independent reflections
  • 536 reflections with I > 2σ(I)
  • R int = 0.045

Refinement

  • R[F 2 > 2σ(F 2)] = 0.027
  • wR(F 2) = 0.057
  • S = 1.09
  • 899 reflections
  • 104 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 0.08 e Å−3
  • Δρmin = −0.11 e Å−3

Data collection: COLLECT (Nonius, 1998 [triangle]); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997 [triangle]); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL-Plus (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003 [triangle]).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808004376/hb2698sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808004376/hb2698Isup2.hkl

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

Acknowledgments

Funding by the Deutsche Forschungsgemeinschaft (Emmy–Noether grant Nos. AR493-1 and -2 to HDA), the Fonds der Chemischen Industrie, and the IMPRS Chemical Biology (to JYL and WZS) is gratefully acknowledged.

supplementary crystallographic information

Comment

Oxime geometry has been found to be important for determining their reactivity in cycloadditions and pericyclic reactions (e.g. François et al., 2004). The title compound, (I), was prepared in the study of hetero-Diels–Alder reactions to form 3-hydroxy-pyridines (Lu & Arndt, 2007; Fletcher et al., 2006).

The crystal structure of (I) (Fig. 1) verifies earlier studies by NMR and IR (Buehler, 1967; Karabatsos & Taller, 1968; Levy & Nelson, 1972; Jirman et al., 1990; Corrêa & Moran, 1999) of Z-configured oximes and forms a basis for further studies in the field. Interestingly, the C1/O2/O4 carboxyl group in (I) adopts a dihedral angle of 93° with respect to the coplanar N?C—C?O π-system, which indicates complete absence of electronic conjugation.

Experimental

A stirred solution of 7.25 g (50.0 mmol) of Z-Methyl 2-(hydroxyimino)-3-oxobutanoate (Lu & Arndt, 2007; Fletcher et al., 2006) in anhydrous acetone (50 ml) was cooled to 273 K and potassium carbonate (3.8 g, 27.5 mmol) was added, followed by dimethyl sulfate (5.70 ml, 60.0 mmol). The stirred reaction mixture was warmed to room temperature over 2 h and kept stirring for 10 h (TLC control). The reaction mixture was filtered and the solid residue was rinsed with acetone (3 × 10 ml). The combined filtrates were evaporated to dryness, redissolved in Et2O (100 ml), washed with sat. NaCl solution (3 × 40 ml) and dried with Na2SO4. Concentration and purification by column chromatography (100 g SiO2, EtOAc/light petroleum v/v = 1:8) gave 7.60 g (47.8 mmol, 96%) of the title compound as a colourless oil which crystallized on standing as colourless cubes.

Mp = 335–337 K; Rf = 0.46 (SiO2, EtOAc/cyclohexane = 1:2); 1H NMR (400 MHz, CDCl3) δ = 2.38 (3H, s, C(O)CH3), 3.85 (3H, s, =NOCH3), 4.08 (3H, s, COOCH3); 13C NMR (100.6 MHz, CDCl3) δ = 25.1 (C(O)CH3), 52.5 (COOCH3), 64.4 (NOCH3), 149.9 (C=N), 161.5 (COOCH3), 192.7 (C(O)CH3); IR (KBr): ν = 3009w, 2951w, 1744 s, 1683 s, 1596 s, 1241 s, 1021 s, 841 s cm-1; HRMS (EI): m/Z calc. for C6H9NO4 [M+]: 159.0532, found: 159.0524.

Refinement

Anomalous dispersion was negligible and Friedel pairs were merged before refinement.

The H atoms were placed in calculated positions, with C—H = 0.96 Å and were refined as riding, with Uiso(H) = 1.5Ueq(C); the methyl groups were allowed to rotate but not to tip.

Figures

Fig. 1.
The molecular structure of (I) with displacement ellipsoids shown at the 30% probability level (arbitrary spheres for the H atoms).

Crystal data

C6H9NO4F000 = 336
Mr = 159.14Dx = 1.296 Mg m3
Orthorhombic, Pna21Mo Kα radiation λ = 0.71073 Å
Hall symbol: P 2c -2nCell parameters from 3104 reflections
a = 8.3410 (17) Åθ = 3.0–27.5º
b = 13.410 (3) ŵ = 0.11 mm1
c = 7.2900 (15) ÅT = 291 (1) K
V = 815.4 (3) Å3Cube, colourless
Z = 40.2 × 0.2 × 0.2 mm

Data collection

Nonius KappaCCD diffractometer899 independent reflections
Radiation source: fine-focus sealed tube536 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.045
Detector resolution: 19 vertical, 18 horizontal pixels mm-1θmax = 26.4º
T = 291(1) Kθmin = 3.9º
213 frames via ω–rotation (Δω = 1%) and two times 40 s per frame (four sets at different κ–angles) scansh = −10→10
Absorption correction: nonek = −16→16
3104 measured reflectionsl = −9→9

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-atom parameters constrained
wR(F2) = 0.057  w = 1/[σ2(Fo2) + (0.0206P)2] where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max < 0.001
899 reflectionsΔρmax = 0.08 e Å3
104 parametersΔρmin = −0.11 e Å3
1 restraintExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.087 (6)

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
O10.14686 (19)0.12432 (11)0.8457 (2)0.0633 (5)
O20.1931 (2)0.03995 (12)0.4285 (2)0.0784 (6)
O30.4017 (2)0.23981 (12)0.3446 (3)0.0923 (7)
O40.4114 (2)0.03491 (11)0.6049 (2)0.0634 (5)
N10.19750 (19)0.20788 (12)0.7495 (3)0.0536 (5)
C10.2847 (3)0.07762 (15)0.5349 (3)0.0520 (6)
C30.2673 (2)0.18321 (15)0.5998 (3)0.0463 (5)
C50.3291 (3)0.26405 (17)0.4804 (3)0.0557 (6)
C70.0702 (3)0.15466 (19)1.0136 (3)0.0749 (8)
H7A0.03490.09671.07960.112*
H7B−0.02050.19610.98570.112*
H7C0.14490.19141.08750.112*
C80.4383 (4)−0.06865 (16)0.5537 (3)0.0819 (9)
H8A0.5226−0.09600.62790.123*
H8D0.4683−0.07210.42680.123*
H8B0.3416−0.10610.57270.123*
C90.3008 (3)0.37018 (15)0.5307 (4)0.0674 (7)
H9A0.34810.41280.43970.101*
H9B0.34840.38360.64800.101*
H9D0.18750.38260.53670.101*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0881 (11)0.0498 (9)0.0519 (9)−0.0045 (8)0.0208 (9)0.0002 (9)
O20.0868 (13)0.0657 (11)0.0828 (13)0.0028 (9)−0.0205 (12)−0.0202 (11)
O30.1322 (17)0.0691 (12)0.0755 (13)−0.0101 (10)0.0492 (14)−0.0068 (11)
O40.0676 (10)0.0551 (9)0.0675 (10)0.0137 (8)−0.0078 (9)−0.0037 (9)
N10.0625 (12)0.0471 (11)0.0510 (12)−0.0028 (9)0.0046 (12)0.0004 (10)
C10.0601 (14)0.0494 (13)0.0467 (14)−0.0018 (13)0.0041 (14)−0.0023 (13)
C30.0483 (12)0.0491 (13)0.0415 (12)0.0010 (10)−0.0001 (12)−0.0037 (12)
C50.0615 (16)0.0567 (15)0.0490 (14)−0.0031 (12)0.0063 (13)−0.0008 (13)
C70.0981 (19)0.0731 (17)0.0535 (16)−0.0063 (16)0.0276 (15)−0.0040 (14)
C80.1075 (19)0.0597 (17)0.079 (2)0.0278 (14)0.0040 (16)0.0008 (15)
C90.0773 (15)0.0517 (14)0.0732 (17)−0.0057 (13)0.0087 (13)0.0009 (15)

Geometric parameters (Å, °)

O1—N11.387 (2)C7—H7A0.9600
O1—C71.440 (3)C7—H7B0.9600
O2—C11.200 (3)C7—H7C0.9600
O3—C51.205 (3)C8—H8A0.9600
O4—C11.306 (3)C8—H8D0.9600
O4—C81.455 (2)C8—H8B0.9600
N1—C31.281 (3)C9—H9A0.9600
C1—C31.500 (3)C9—H9B0.9600
C3—C51.483 (3)C9—H9D0.9600
C5—C91.489 (3)
N1—O1—C7109.67 (16)O1—C7—H7C109.5
C1—O4—C8116.29 (19)H7A—C7—H7C109.5
C3—N1—O1111.12 (17)H7B—C7—H7C109.5
O2—C1—O4125.7 (2)O4—C8—H8A109.5
O2—C1—C3122.6 (2)O4—C8—H8D109.5
O4—C1—C3111.7 (2)H8A—C8—H8D109.5
N1—C3—C5118.01 (19)O4—C8—H8B109.5
N1—C3—C1123.8 (2)H8A—C8—H8B109.5
C5—C3—C1118.1 (2)H8D—C8—H8B109.5
O3—C5—C3117.4 (2)C5—C9—H9A109.5
O3—C5—C9122.7 (2)C5—C9—H9B109.5
C3—C5—C9119.9 (2)H9A—C9—H9B109.5
O1—C7—H7A109.5C5—C9—H9D109.5
O1—C7—H7B109.5H9A—C9—H9D109.5
H7A—C7—H7B109.5H9B—C9—H9D109.5

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB2698).

References

  • Buehler, E. (1967). J. Org. Chem.32, 261–265.
  • Corrêa, I. R. Jr & Moran, P. J. S. (1999). Tetrahedron, 55, 14221–14232.
  • Fletcher, M. D., Hurst, T. E., Miles, T. J. & Moody, C. J. (2006). Tetrahedron, 62, 5454–5463.
  • François, D., Madden, A. & Murray, W. V. (2004). Org. Lett.6, 1931–1934. [PubMed]
  • Jirman, J., Lycka, A. & Ludwig, M. (1990). Collect. Czech. Chem. Commun.55, 136–146.
  • Karabatsos, G. J. & Taller, R. A. (1968). Tetrahedron, 24, 3347–3360.
  • Levy, G. C. & Nelson, G. L. (1972). J. Am. Chem. Soc.94, 4897–4901.
  • Lu, J.-Y. & Arndt, H.-D. (2007). J. Org. Chem.72, 4205–4212. [PubMed]
  • Nonius (1998). 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 Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography