Diethyl 2-oxo-3-(2-oxo-2,3-dihydro-1H-indol-3-yl­idene)butane­dioate

I K LeninTamikovan; A SubbiahPandi; M Damodiran; K Karthikeyan; P T Perumal

doi:10.1107/S160053680905140X

. 2009 Dec 4;66(Pt 1):o37. doi: 10.1107/S160053680905140X

Diethyl 2-oxo-3-(2-oxo-2,3-dihydro-1H-indol-3-ylidene)butanedioate

I K LeninTamikovan ^a, A SubbiahPandi ^b,^*, M Damodiran ^c, K Karthikeyan ^c, P T Perumal ^c

PMCID: PMC2980112 PMID: 21580142

Abstract

The title compound, C₁₆H₁₅NO₆, crystallizes with two symmetry–independent molecules in the asymmetric unit. The crystal structure is stabilized by intermolecular C—H⋯O and N—H⋯O hydrogen bonds, and intramolecular C—H⋯O hydrogen bonds. In addition, the crystal structure exhibits two intermolecular C—H⋯π interactions.

Related literature

For the use of indole derivatives as bioactive drugs, see: Stevenson et al. (2000 ▶). They exhibit anti-allergic, central nervous system depressant and muscle-relaxant properties, see: Harris & Uhle (1960 ▶); Ho et al. (1986 ▶). Indoles also exhibit high aldose reductase inhibitory activity, see: Rajeswaran et al. (1999 ▶). For bond-length data, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₁₆H₁₅NO₆
M _r = 317.29
Triclinic,
a = 8.8277 (2) Å
b = 13.5365 (4) Å
c = 13.6300 (3) Å
α = 96.516 (3)°
β = 102.218 (2)°
γ = 100.668 (1)°
V = 1544.44 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 293 K
0.24 × 0.22 × 0.16 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2001 ▶) T _min = 0.975, T _max = 0.983
37712 measured reflections
8406 independent reflections
5743 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.056
wR(F ²) = 0.190
S = 1.02
8406 reflections
420 parameters
H-atom parameters constrained
Δρ_max = 0.60 e Å⁻³
Δρ_min = −0.35 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); data reduction: SAINT and XPREP (Bruker, 2004 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia (1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97 and PLATON.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680905140X/lx2125sup1.cif

e-66-00o37-sup1.cif^{(28KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680905140X/lx2125Isup2.hkl

e-66-00o37-Isup2.hkl^{(402.9KB, 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
C4—H4⋯O5	0.93	2.28	2.984 (3)	133
C20—H20⋯O12	0.93	2.24	2.944 (3)	132
N1—H1⋯O8ⁱ	0.86	2.38	3.126 (2)	146
N2—H2⋯O2ⁱⁱ	0.86	2.25	3.088 (2)	163
C21—H21⋯O9ⁱⁱⁱ	0.93	2.60	3.431 (3)	149
C23—H23⋯O1ⁱⁱ	0.93	2.34	3.254 (3)	166
C29—H29A⋯Cg1ⁱ	0.96	2.75	3.530 (3)	139
C31—H31B⋯Cg2^iv	0.97	2.69	3.597 (2)	156

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) . Cg1 and Cg2 are the centroids of the C3–C8 benzene ring and the N1/C1–C3/C8 pyrrole ring, respectively.

Acknowledgments

The authors thank Babu Varghese, SAIF, IIT, Madras, India, for his help with the data collection.

supplementary crystallographic information

Comment

Indole derivatives are used as bioactive drugs (Stevenson et al., 2000) and they exhibit anti-allergic, central nervous system depressant and muscle relaxant properties (Harris & Uhle 1960; Ho et al., 1986). Indoles have been proved to display high aldose reductase inhibitory activity (Rajeswaran et al., 1999). Against this background, we report the crystal structure of the title compound, which has two unique molecules in the asymmetric unit (further marked as A & B) (Fig. 1).

In the crystal structure, the bond lengths and angles are found to have normal values (Allen et al., 1987). The indole unit is essentially planar, with a mean deviation of -0.022 (2) Å for A, 0.018 (2) Å for B, respectively, from the least-squares plane defined by the nine constituent atoms. Intramolecular C4—H4···O5 and C20—H20···O12 hydrogen bonds generate S(7) ring motifs (Bernstein et al., 1995). The crystal packing is stabilized by intermolecular C—H···O and N—H···O hydrogen bonds. Atom N1 in the molecule at (x, y, z) donate one proton to atom O8 in the molecule at (-x, -y, 1 - z) forming a C(7) chain along c axis. Also, atoms N2 and C23 in the molecule at (x, y, z) donate one proton each to atom O2 and O1 in the molecule at (-x, 1 - y, 1 - z) generating R₂²(11) ring motif. The molecules at (x, y, z) and (1 - x, 1 - y, 1 - z) are linked by C21—H21···O9 hydrogen bonds into cyclic centrosymmetric R₂²(18) dimers (Table 1). The molecular packing (Fig. 2) is further stabilized by intermolecular C—H···π interactions; the first between the methyl H atom and the benzene ring of an adjacent molecule, with a C29–H29A···Cg1ⁱ, the second between the methyl H atom and the pyrrole ring of a neighbouring molecule, with a C31–H31B···Cg2ⁱⁱ (Table 1; Cg1 and Cg2 are the centroids of the C3–C8 benzene ring and the N1/C1/C2/C3/C8 pyrrole ring, respectively).

Experimental

To a magnetically stirred solution of isatin (2 mmol) and aniline (2 mmol) in ethanol (3 ml) was added drop wise, dimethyl acetylenedicarboxylate (2 mmol, 0.284 g) at room temperature over 10 min. After complete the reaction as indicated by TLC water was added. The reaction mixture was extracted with ethyl acetate (2x30 ml) and the organic layer was separated carefully from the aqueous layer. The combined organic layers were dried over anhydrous Na₂SO₄ by which the water present after the extraction can be removed and further, the organic layer is concentrated in vacuum. The crude was purified by column chromatography on silica gel (Merck, 100–200 mesh, ethyl acetate-petroleum ether (15:85). Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a solution of the title compound in ethanol:petroleum ether (3:1)at room temperature.