Ethyl 4-(tert-butyl­amino)-3-nitro­benzoate

Siti Marina Mohd Maidin; Aisyah Saad Abdul Rahim; Hasnah Osman; Reza Kia; Hoong-Kun Fun

doi:10.1107/S160053680802206X

. 2008 Jul 19;64(Pt 8):o1550–o1551. doi: 10.1107/S160053680802206X

Ethyl 4-(tert-butylamino)-3-nitrobenzoate

Siti Marina Mohd Maidin ^a, Aisyah Saad Abdul Rahim ^a,^‡, Hasnah Osman ^b, Reza Kia ^c, Hoong-Kun Fun ^c,^*

PMCID: PMC2962174 PMID: 21203254

Abstract

In the title compound, C₁₃H₁₈N₂O₄, intramolecular N—H⋯O, N—H⋯N and C—H⋯O (× 3) hydrogen bonds generate S(6) and S(5) ring motifs. There are two crystallographically independent molecules (A and B) in the asymmetric unit. The nitro group is coplanar with the benzene ring, with O—N—C—C torsion angles of −0.33 (13) and 0.93 (14)° in molecules A and B, respectively. In the crystal structure, neighbouring molecules are linked together by intermolecular C—H⋯O hydrogen bonds. In addition, the crystal structure is stabilized by π–π interactions with centroid–centroid distances ranging from 3.7853 (6) to 3.8625 (6) Å.

Related literature

For literature on hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For values of bond lengths, see: Allen et al. (1987 ▶). For related literature, see, for example: Göker et al. (1998 ▶); Anderson (2005 ▶); Kakei et al. (1993 ▶).

Experimental

Crystal data

C₁₃H₁₈N₂O₄
M _r = 266.29
Monoclinic,
a = 16.0471 (5) Å
b = 6.6417 (2) Å
c = 30.0180 (9) Å
β = 121.688 (2)°
V = 2722.37 (14) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100.0 (1) K
0.51 × 0.43 × 0.17 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.879, T _max = 0.984
63326 measured reflections
8141 independent reflections
6368 reflections with I > 2σ(I)
R _int = 0.033

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.133
S = 1.04
8141 reflections
351 parameters
H-atom parameters constrained
Δρ_max = 0.53 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005 ▶); 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, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680802206X/at2594sup1.cif

e-64-o1550-sup1.cif^{(24.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802206X/at2594Isup2.hkl

e-64-o1550-Isup2.hkl^{(398.3KB, hkl)}

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

Table 1. Selected centroid–centroid distances (Å).

Cg1 and Cg2 are the centroids of the C1A–C6A and C1B–C6B rings, respectively.

Cg1⋯Cg2ⁱ	3.7853 (6)
Cg1⋯Cg2ⁱⁱ	3.8625 (6)

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

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2A—H2NA⋯O4A	0.86	1.93	2.6299 (15)	138
N2A—H2NA⋯N1A	0.86	2.54	2.9361 (15)	109
N2B—H2NB⋯O4B	0.87	1.95	2.6355 (15)	134
N2B—H2NB⋯N1B	0.87	2.58	2.9419 (15)	106
C1A—H1A⋯O3A	0.95	2.31	2.6522 (16)	100
C1B—H1B⋯O3B	0.95	2.31	2.6498 (16)	100
C4A—H4A⋯O3Bⁱⁱⁱ	0.95	2.50	3.4124 (17)	160
C4B—H4B⋯O3A^iv	0.95	2.42	3.2566 (18)	147
C5A—H5A⋯O1A	0.95	2.41	2.7326 (13)	100
C11A—H11A⋯O2B^v	0.98	2.55	3.4714 (17)	157
C11B—H11F⋯O2Aⁱⁱ	0.98	2.52	3.4446 (17)	158
C13B—H13D⋯O2A^vi	0.98	2.60	3.5071 (17)	154

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Symmetry codes: (ii) Inline graphic ; (iii) ; (iv) ; (v) ; (vi) .

Acknowledgments

We are grateful to the Malaysian Government and Universiti Sains Malaysia (USM) for financial support given under the USM Research University funding (1001/PFARMASI/815026). HKF and RK thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/ 613312. RK thanks Universiti Sains Malaysia for a postdoctoral research fellowship.

supplementary crystallographic information

Comment

As a part of our ongoing studies on new nitro benzoic acid derivatives, we have synthesized the title compound (I) employing a modified protocol of previous procedure (Göker et al., 1998). The nitro benzoic acid intermediates are a convenient starting material for the synthesis of heterocycles targeting important biological processes, e.g. antifungal (Fluconazole) (Anderson, 2005) and proton pump inhibitor (Omeprazole) (Kakei et al., 1993). The crystal structure of the tert-butylamino functionalized nitro benzoic acid (I) has been determined, and herein, we present a full report on its crystal structure.

In the title compound (I) (Fig. 1), intramolecular N—H···O (x 2), N—H···N (x 2), and C—H···O (x 3) hydrogen bonds (Table 2) generate S(6) and S(5) ring motifs, respectively (Bernstein et al., 1995). There are two crystallographically independent molecules, A and B in the asymmetric unit of the title compound. The nitro group is coplanar with the benzene ring with torsion angle of -0.33 (13) and 0.93 (14)° in the molecule A and B, respectively. In the crystal structure neighbouring molecules are linked together by intermolecular C—H···O hydrogen bonds (Table 1). In the crystal packing (Table 2 & Fig. 2), molecules are stacked down the b axis, being consolidated by π–π interactions with centroid to centroid distances ranging from 3.7853 (6) – 3.8625 (6) Å.

The crystal structure is stabilized by intramolecular N—H···O (x 2), N—H···N (x 2), C—H···O (x 3), and intermolecular C—H···O (x 5) hydrogen bonds and π–π interactions.

Experimental

Ethyl 4-fluoro-3-nitrobenzoate (200 mg, 0.93 mmol) was dissolved in dry dichloromethane (10 ml). N, N-diisopropylethylamine (DIPEA) (0.20 ml, 1.12 mmol) was added to the stirred mixture. Then, tert-butylamine (0.11 ml, 1.03 mmol) was added dropwise using syringe and stirred at room temperature under N₂ overnight. After completion of the reaction, the mixture was washed with 10% NaCO₃ (10 ml). The aqueous layer was washed with dichloromethane (3 x 15 ml). The organic layers were collected and dried over MgSO₄(anhydrous). The solvent was removed under reduced pressure to yield the crude product. Recrystallisation with hot hexane revealed the title compound (I) as bright yellow crystals.