Diethyl 4,6-diacetamido­isophthalate

Peishen Li; Xianghui Li; Chao Chen; Lihua Yuan; Wen Feng

doi:10.1107/S1600536811013845

. 2011 Apr 22;67(Pt 5):o1185. doi: 10.1107/S1600536811013845

Diethyl 4,6-diacetamidoisophthalate

Peishen Li ^a, Xianghui Li ^a, Chao Chen ^a, Lihua Yuan ^a, Wen Feng ^a,^*

PMCID: PMC3089246 PMID: 21754487

Abstract

In the title compound, C₁₆H₂₀N₂O₆, two intramolecular N—H⋯O hydrogen bonds occur, in which the carbonyl O atoms of the ethyl acetate groups serve as the acceptor atoms; both motifs generate S(6) rings. In the crystal, molecules are linked by weak C—H⋯O links (with the acceptor O atoms part of the amide groups), generating [001] chains.

Related literature

For background to intramolecular hydrogen bonds this class of compound, see: Zhu et al. (2000 ▶); Yuan et al. (2004 ▶); Feng et al. (2009 ▶); Yan et al. (2010 ▶); Zhang et al. (2008 ▶). For a related structure, see: Zhang et al. (2006 ▶).

Experimental

Crystal data

C₁₆H₂₀N₂O₆
M _r = 336.34
Triclinic,
a = 7.951 (3) Å
b = 10.249 (3) Å
c = 11.109 (4) Å
α = 76.70 (3)°
β = 77.42 (3)°
γ = 76.50 (2)°
V = 843.7 (5) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 292 K
0.50 × 0.46 × 0.40 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
3149 measured reflections
3094 independent reflections
1826 reflections with I > 2σ(I)
R _int = 0.004
3 standard reflections every 150 reflections intensity decay: 4.5%

Refinement

R[F ² > 2σ(F ²)] = 0.079
wR(F ²) = 0.268
S = 1.09
3094 reflections
223 parameters
4 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.59 e Å⁻³
Δρ_min = −0.65 e Å⁻³

Data collection: DIFRAC (Gabe et al., 1993 ▶); cell refinement: DIFRAC; data reduction: NRCVAX (Gabe et al., 1989 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811013845/hb5828sup1.cif

e-67-o1185-sup1.cif^{(19.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811013845/hb5828Isup2.hkl

e-67-o1185-Isup2.hkl^{(151.8KB, 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
N1—H1N⋯O2	0.88 (4)	1.92 (3)	2.676 (4)	144 (3)
N2—H2N⋯O6	0.81 (4)	1.96 (4)	2.656 (4)	143 (3)
C9—H9B⋯O3ⁱ	0.96	2.54	3.445 (6)	157
C16—H16A⋯O4ⁱⁱ	0.96	2.57	3.485 (7)	160

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

Acknowledgments

The authors acknowledge the National Natural Science Foundation of China (20774059) for funding this work, and the Analytical & Testing Center of Sichuan University for the X-ray analysis.

supplementary crystallographic information

Comment

Hydrogen bonds play a vital role in assisting formation of aromatic oligoamide foldmers and macrocycles (Zhu et al., 2000; Yuan et al., 2004; Feng et al., 2009). It is important to examine the structural feature of the backbones that is responsible for the formation of foldmers and macrocycles. Research has focused on the role of intramolecular hydrogen bonds in regulating conformations and interactions both in solution and the solid state (Yan et al., 2010; Zhang et al. 2008). Herein, we report on the crystal structure of the aromatic monomer containing intramolecular hydrogen bonds, which could be applied as important building blocks to construct macrocycles.

The title compound comprises two similar six-member hydrogen bonds. There are two possible comformations: (a) one with the ethoxy O atoms involving in the intramolecular NH···OC₂H₅ six-member hydrogen bonds (conformation a), and (b) the other with carbonyl O atoms that form intramolecualr H-bonds (conformation b) (Fig. 1). However, the crystal structure revealed the existence of two six-member hydrogen bonds that involve carbonyl O atoms, indicating that conformation b is more stable and is sustained by two intromolecular hydrogen bond N1H1···O2 (Table1, Fig. 2). It is expected that this type of hydrogen bonds may be exploited to construct macrocyles and supamolecular architecture with folded conformations. In the crystal, the molecules are linked by C—H···O interactions.

Experimental

For synthesis of the title compound, Pd/C (50 mg) was added to the solution of diethyl 4,6-dinitroisophthalate (500 mg, 1.60 mmol) in CH₂Cl₂ and the mixture was stirred at room temperature under H₂ atmosphere for 6 h. After removal of Pd/C and solvent, the white solid was obtained and then dissolved in CH₂Cl₂ (50 ml). Et₃N (335 mg, 3.31 mmol) was added to the above solution followed by dropping acetyl chloride (350 mg, 4.46 mmol). After stirring 2 h at room temperature, the mixture was washed with distilled water, dried over anhydrous Na₂SO₄. Removal of solvent under reduced pressure gave the crude product, which was recrystallized from methanol to yield the white product (430 mg, yield 79.8%). ¹H NMR (400 MHz, CDCl₃): δ 10.95 (s, 2H), 9.98 (s, 1H), 8.74 (s, 1H), 4.35 (m, 4H), 2.25 (s, 6H), 1.20 (t, J = 6.4 Hz, 6H).

The crystal of the title compound was grown from the THF solution. This compound was dissolved in THF and filtered, then the filtrate was allowed to stand undisturbed to give the single-crystal.