Ethyl 4-butyl­amino-3-nitro­benzoate

Shivanagere Nagojappa Narendra Babu; Aisyah Saad Abdul Rahim; Shafida Abd Hamid; Kasthuri Balasubramani; Hoong-Kun Fun

doi:10.1107/S1600536809029754

. 2009 Aug 8;65(Pt 9):o2070–o2071. doi: 10.1107/S1600536809029754

Ethyl 4-butylamino-3-nitrobenzoate

Shivanagere Nagojappa Narendra Babu ^a, Aisyah Saad Abdul Rahim ^a,^‡, Shafida Abd Hamid ^b, Kasthuri Balasubramani ^c, Hoong-Kun Fun ^c,^*,^§

PMCID: PMC2970083 PMID: 21577493

Abstract

In the crystal structure of the title compound, C₁₃H₁₈N₂O₄, the asymmetric unit consists of three crystallographically independent ethyl 4-butylamino-3-nitrobenzoate molecules. There is an intramolecular N—H⋯O hydrogen bond in each molecule, which generates an S(6) ring motif. The structure is stabilized by intermolecular N—H⋯O and C—H⋯O hydrogen bonds.

Related literature

For nitrobenzoic acid, see: Brouillette et al. (1999 ▶); Williams et al. (1995 ▶); For benzimdazole derivatives, see Ozden et al. (2005 ▶); Beaulieu et al. (2004 ▶); Kilburn et al. (2000 ▶).

Experimental

Crystal data

C₁₃H₁₈N₂O₄
M _r = 266.29
Monoclinic,
a = 65.292 (2) Å
b = 3.9555 (2) Å
c = 31.4417 (11) Å
β = 104.833 (3)°
V = 7849.6 (5) Å³
Z = 24
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.40 × 0.19 × 0.03 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.915, T _max = 0.997
85498 measured reflections
8991 independent reflections
6753 reflections with I > 2σ(I)
R _int = 0.090

Refinement

R[F ² > 2σ(F ²)] = 0.076
wR(F ²) = 0.177
S = 1.13
8991 reflections
532 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809029754/bq2152sup1.cif

e-65-o2070-sup1.cif^{(34.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809029754/bq2152Isup2.hkl

e-65-o2070-Isup2.hkl^{(431KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2A—H2NA⋯O4Aⁱ	0.89 (3)	2.51 (3)	3.345 (3)	156 (3)
C1A—H1AA⋯O3Aⁱⁱ	0.96	2.41	3.267 (3)	149
N2B—H2NB⋯O4B	0.83 (3)	2.02 (3)	2.637 (3)	130 (3)
N2A—H2NA⋯O4A	0.89 (3)	1.97 (3)	2.636 (3)	131 (3)
N2C—H2NC⋯O4C	0.82 (3)	2.02 (4)	2.635 (3)	132 (3)
C10A—H10F⋯O1B	0.97	2.58	3.542 (4)	169

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

SNNB, ASAR and SAH are grateful to Universiti Sains Malaysia (USM) for funding the synthetic chemistry work under the University Research Grant (1001/PFARMASI/815026). SNNB acknowledges the USM for a Postdoctoral Research Fellowship. HKF and KBS thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. KBS thanks Universiti Sains Malaysia for a post–doctoral research fellowship. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012.

supplementary crystallographic information

Comment

Nitro benzoic acid derivatives are important intermediates for the synthesis of various heterocyclic compounds of pharmacological interest (Brouillette et al. 1999; Williams et al. 1995). The synthesis of novel methyl or ethyl 1H-benzimidazole-5-carboxylates derivatives (Ozden et al. 2005), non-nucleoside benzimidazole-based allosteric inhibitors of the hepatitis C virus ns5b polymerase inhibitors (Beaulieu et al. 2004) and solid-phase synthesis of substituted 2-aminomethyl benzimidazoles (Kilburn et al. 2000) were commonly accessed via nitrobenzoic acid derivatives. As part of an ongoing study on such compounds, in this paper, we present the crystal structure of the title compound, (I), which was synthesized as an intermediate.

The asymmetric unit of (I) consists of three crystallographically independent ethyl 4-(butylamino)-3-nitrobenzoate molecules (A, B & C), as shown in Fig. 1. Three intramolecular N—H···O hydrogen bonds generate S(6) ring motifs (Table 1).

In the crystal structure, in two molecules (A & B), the hydrogen atom attached to the nitrogen atom is hydrogen-bonded to the nitro group oxygen atoms via N—H···O hydrogen bonds to form tandem hydrogen bonds. Here both the hydrogen atoms act as bifurcated donor and the oxygen atom act as bifurcated acceptor. In addition, these neighboring molecules are linked by C—H···O hydrogen bonds along the [1 0 0] direction. Interestingly enough, the molecules C are not linked by any intermolecular interactions (Fig. 2).

Experimental

The title compound was synthesized by adding N,N-diisopropyl ethylamine (DIPEA) (0.20 ml, 1.12 mmol) dropwise to a stirred solution of ethyl 4-fluoro-3-nitrobenzoate (0.21 g, 1 mmol) in dry dichloromethane (10 ml). Butylamine (0.10 ml, 1 mmol) was added slowly with stirring, and then the mixture was stirred overnight at room temperature under N₂. After completion of the reaction, the mixture was washed with 10% Na₂CO₃ (10 ml). The aqueous layer was washed again with dichloromethane (3 × 10 ml). The organic fractions were pooled, dried over MgSO₄ and the solvent was evaporated in vacuo. Recrystallization with hot hexane afforded the title compound as yellow needle-like crystals.