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organic papers
Acta Crystallographica Section E

Structure Reports Online
ISSN 1600-5368

4,6-Dimethyl-5-nitro-1H-pyridin-2-one

Victor B. Rybakov,* Alexander A. Bush, Eugene V. Babaev and Leonid A. Aslanov
Department of Chemistry, Moscow State University, 119992 Moscow, Russian Federation Correspondence e-mail: rybakov@biocryst.phys.msu.su

In the crystal structure of the title compound, C7H8N2O3, molecules form centrosymmetrical dimers via N HÑÑÑO hydrogen bonds.

Received 15 December 2003 Accepted 22 December 2003 Online 17 January 2004

Comment
Previously, we have reported the crystal structure determination of Guareschi pyridone (1a) (Rybakov et al., 2004). Now we have investigated the crystal structure of a related compound, (2), which can be obtained from Guareschi pyridone. A search of Cambridge Structural Database (CSD, Version of November 2002; Allen, 2002) does not give any hits for 4,6-disubstitutied 5-nitro-pyridin-2-ones. The multistep synthesis of (2) has been performed previously (Mariella et al., 1955) by nitration of Guareschi pyridone (1a) and further stepwise hydrolysis of the nitro derivative (1b) to amide (1c) and carboxylic acid (1d), followed by decarboxylation. To obtain compound (2), we simpli?ed the earlier multistep procedure and, after obtaining the crude intermediate product (1b), converted it to the target compound (2) by prolonged re?ux in sulfuric acid.

Key indicators Single-crystal X-ray study T = 293 K Ú Mean ' (CÁC) = 0.003 A R factor = 0.043 wR factor = 0.111 Data-to-parameter ratio = 12.9 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

The structure of the six-membered heterocycle has a well de?ned diene-like fragment (Fig. 1); bond distances C3 C4 and C5 C6 are shorter than the C2 C3 and C4 C5 distances. The C C bonds of the methyl groups, C4 C41 Ú Ú [1.499 (3) A] and C6 C61 [1.501 (3) A], are almost equal in length. The nitro group is twisted away from the attached ring; the dihedral angle between the heterocyclic ring and the O51/ O52/N5/C5 plane is 39.36 (12) . An intramolecular C61 H61BÑÑÑO52 interaction is observed in the molecular structure. In the crystal structure, an N1 H1ÑÑÑO2(1 Ðx, Ðy, 1 Ð z) intermolecular hydrogen bond links the molecules into centrosymmetric dimers (see Fig. 2 and Table 2 for details).

Experimental
# 2004 International Union of Crystallography Printed in Great Britain Á all rights reserved

To a solution of pyridone (1a) (40 g, 0.22 mol) in 150 ml of 98% H2SO4 a mixture of fuming nitrous acid (13 ml) and sulfuric acid (14 ml) was carefully added dropwise, keeping the temperature in the
DOI: 10.1107/S160053680302960X Victor B. Rybakov et al.


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organic papers
Data collection
Enraf Nonius CAD-4 diffractometer Non-pro?led 3 scans Absorption correction: none 1524 measured re?ections 1462 independent re?ections 999 re?ections with I > 2' (I) Rint = 0.037 max = 69.9 h = 11 3 11 k=037 l = 0 3 16 1 standard re?ection every 200 re?ections frequency: 60 min intensity decay: none H atoms treated by a mixture of independent and constrained re?nement w = 1/[' 2(Fo2) + (0.0554P)2] where P = (Fo2 + 2Fc2)/3 (Ñ/' )max < 0.001 Ú Ñ&max = 0.13 e A 3 Ú Ñ&min = 0.15 e A 3

Re?nement Figure 1
ORTEP 3 (Farrugia, 1997) plot of the title compound. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.
Re?nement on F 2 R[F 2 > 2' (F 2)] = 0.043 wR(F 2) = 0.111 S = 0.98 1462 re?ections 113 parameters

Table 1
N1àC6 N1àC2 N1àH1 C2àO2 C2àC3 C3àC4 C4àC5

Ú Selected geometric parameters (A, ).
1.343 (2) 1.379 (2) 0.84 (2) 1.242 (2) 1.426 (3) 1.353 (3) 1.431 (3) 126.17 (19) 118.4 (13) 114.7 (13) 120.11 (19) 125.47 (18) 114.41 (19) 123.15 (19) 117.44 (19) 119.59 (18) 122.91 (19) C4àC41 C5àC6 C5àN5 N5àO52 N5àO51 C6àC61 C6àC5àC4 C6àC5àN5 C4àC5àN5 O52àN5àO51 O52àN5àC5 O51àN5àC5 N1àC6àC5 N1àC6àC61 C5àC6àC61 1.499 1.375 1.454 1.216 1.226 1.501 (3) (3) (3) (2) (2) (3)

C6àN1àC2 C6àN1àH1 C2àN1àH1 O2àC2àN1 O2àC2àC3 N1àC2àC3 C4àC3àC2 C3àC4àC5 C3àC4àC41 C5àC4àC41

121.33 (18) 118.52 (17) 120.14 (18) 122.6 (2) 119.40 (19) 117.95 (18) 117.41 (17) 115.33 (18) 127.25 (18)

Figure 2

PLUTON97 (Spek, 1997) plot showing a N HÑÑÑO hydrogen bonded dimer.

Table 2 range 313 318 K. Increasing the temperature to 338 K during the addition causes a violent explosion. The reaction mixture was kept for 5 d, and it was periodically heated to the temperature 333 343 K (and then even up to 373 K). When the TLC control displayed complete absence of the starting pyridone, the reaction mixture was poured into a ?vefold excess of ice cold water. The yellow precipitate was ?ltered and dried. The resulting material was dissolved in 50% H2SO4 and re?uxed for 2 d. The reaction mixture was poured on to a fourfold excess of cold water, and the precipitate was ?ltered, washed with water (2 Ò 150 ml) and dried. The resulting nitropyridone (2) (12.5 g, 19%) has a melting point of 518 K, compared to 523 K reported by Mariella et al. (1955). 1H NMR spectra (DMSO d6, ): 6.20 (H 3, s, 1H), 3.42 (NH, s, 1H), 2.35 (6 Me, s, 3H), 2.21 (4 Me, s, 3H). Crystal data
C7H8N2O3 Mr = 168.15 Monoclinic, P21 an Ú a = 9.7677 (15) A Ú b = 5.875 (3) A Ú c = 13.7295 (15) A = 100.760 (10) Ú V = 774.0 (4) A3 Z=4 Dx = 1.443 Mg m 3 Cu K radiation Cell parameters from 25 re?ections = 28 31 " = 0.98 mm 1 T = 293 (2) K Needle, colourless 0.30 Ò 0.10 Ò 0.03 mm


Ú Hydrogen bonding geometry (A, ).
DàHÑÑÑA N1àH1ÑÑ ÑO2 C61àH61BÑÑ ÑO52
Symmetry code: (i) 1
i

DàH 0.84 (2) 0.96
xY yY 1 z.

HÑÑ ÑA 1.94 (2) 2.44

DÑÑ ÑA 2.776 (2) 2.809 (3)

DàHÑÑ ÑA 176 (2) 102

The H atom bonded to N atom was located in a difference map and Ú re?ned isotropically [N H 0.84 (2) A]. The H atoms bonded to C Ú atoms were included in calculated positions (C H 0.93 0.96 A) and re?ned as riding atoms, with Uiso(H) set equal to 1.5Ueq(C) for methyl H atoms and 1.2Ueq(C3) for H3. Data collection: CAD 4 EXPRESS (Enraf Nonius, 1994); cell re?nement: CAD 4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to re?ne structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP 3 for Windows (Farrugia, 1997) and PLUTON97 (Spek, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

The authors are indebted to the Russian Foundation for Basic Research for covering the licence fee for use of the Cambridge Structural Database (project No. 02-07-90322).
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References
Allen, H. F. (2002). Acta Cryst. B58, 380. Enraf Nonius (1994). CAD-4 EXPRESS Software. Version 5.0. Enraf Nonius, Delft, The Netherlands. Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837 838. Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany. Mariella, R. P., Callahan, J. J. & Jibril, A. O. (1955). J. Org. Chem. 20, 1721 1728. Rybakov, V. B., Bush, A. A., Babaev, E. V., & Aslanov, L. A. (2004). Acta Cryst. E60, o160 o161. Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Ø Gottingen, Germany. Spek, A. L. (1997). PLUTON97. University of Utrecht, The Netherlands.

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