5-Amino-6-benzoyl-8-nitro-2,3-di­hydro-1H-spiro­[imidazo[1,2-a]pyridine-7,3′-indolin]-2′-one dimethyl sulfoxide monosolvate

R A Nagalakshmi; J Suresh; S Sivakumar; R Ranjith Kumar; P L Nilantha Lakshman

doi:10.1107/S1600536814008800

. 2014 Apr 26;70(Pt 5):o604–o605. doi: 10.1107/S1600536814008800

5-Amino-6-benzoyl-8-nitro-2,3-dihydro-1H-spiro[imidazo[1,2-a]pyridine-7,3′-indolin]-2′-one dimethyl sulfoxide monosolvate

R A Nagalakshmi ^a, J Suresh ^a, S Sivakumar ^b, R Ranjith Kumar ^b, P L Nilantha Lakshman ^c,^*

PMCID: PMC4011289 PMID: 24860398

Abstract

In the title compound C₂₁H₁₇N₅O₄·C₂H₆OS, the central six-membered ring derived from 1,4-dihydropyridine adopts a distorted boat conformation with a small puckering amplitude of 0.127 (3) Å. The sums of bond angles around the pyridine N atom [358.7 (2)°] and the other imidazolidine N atom [60 (2)°] indicate that these atoms are in sp² hybridization, leading to an essentially planar imidazolidine ring. The last heterocycle, an oxindole moiety, is also nearly planar with an r.m.s. deviation of 0.0185 (1) Å. The amine NH₂ group forms an intramolecular hydrogen bond with the benzoyl group, giving a S(6) motif. In the crystal, N—H⋯O hydrogen bonds lead to the formation of chains along the c-axis direction. Within the chains there are further N—H⋯O and C—H⋯O hydrogen bonds enclosing R ² ₂(14) ring motifs. The chains are linked via N—H⋯O and C—H⋯O hydrogen bonds involving the dimethyl sulfoxide solvent molecule which acts as both an acceptor and a donor..

Related literature

For a previous related work, see: Suresh et al. (2013 ▶). For conformational analysis of ring systems, and small rings fused to benzene, see: Cremer & Pople (1975 ▶); Allen (1981 ▶). graphic file with name e-70-0o604-scheme1.jpg

Experimental

Crystal data

C₂₁H₁₇N₅O₄·C₂H₆OS
M _r = 481.52
Monoclinic,
a = 16.476 (3) Å
b = 13.527 (2) Å
c = 10.0727 (18) Å
β = 99.868 (5)°
V = 2211.7 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.19 mm⁻¹
T = 293 K
0.21 × 0.19 × 0.18 mm

Data collection

Bruker Kappa APEXII diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.967, T _max = 0.974
31940 measured reflections
4109 independent reflections
2818 reflections with I > 2σ(I)
R _int = 0.070

Refinement

R[F ² > 2σ(F ²)] = 0.056
wR(F ²) = 0.160
S = 1.05
4109 reflections
307 parameters
H-atom parameters constrained
Δρ_max = 0.92 e Å⁻³
Δρ_min = −0.47 e Å⁻³

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

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536814008800/bh2496sup1.cif

e-70-0o604-sup1.cif^{(23.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814008800/bh2496Isup2.hkl

e-70-0o604-Isup2.hkl^{(197.3KB, hkl)}

CCDC reference: 998123

Additional supporting information: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2B⋯O4	0.86	1.92	2.549 (3)	129
N2—H2A⋯O3ⁱ	0.86	2.30	2.939 (3)	131
N3—H3⋯O5ⁱⁱ	0.86	1.92	2.779 (4)	177
N5—H5⋯O3ⁱⁱⁱ	0.86	2.31	2.924 (3)	129
C6—H6B⋯O2ⁱⁱⁱ	0.97	2.59	3.274 (4)	128
C11—H11⋯O4ⁱ	0.93	2.43	3.346 (4)	167
C15—H15C⋯O2^iv	0.96	2.55	3.448 (4)	156

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

Acknowledgments

JS and RAN thank the management of the Madura College for their encouragement and support. RRK thanks the DST, New Delhi, for funds under the fast-track scheme (No. SR/FT/CS-073/2009).

supplementary crystallographic information

1. Introduction

2. Experimental

2.1. Synthesis and crystallization

A mixture of benzoylacetonitrile (1.0 mmol), isatin (1.0 mmol) and 2-(nitromethylene) imidazolidine was dissolved in 10 ml of EtOH, and triethylamine (1.0 mmol) was added. The reaction mixture was refluxed for 45 min. After completion of the reaction, as evident from TLC, the precipitated solid product was filtered and dried to obtain pure pale brown solid. Yield 94%. Melting point 530 K.

2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms were placed in calculated positions and allowed to ride on their carrier atoms with C—H = 0.93 (aromatic CH), 0.96 (methyl CH₃) or 0.97 Å (methylene CH₂), and N—H = 0.86 Å. Isotropic displacement parameters for H atoms were calculated as U_iso = 1.5U_eq(C) for CH₃ groups and U_iso = 1.2U_eq(carrier atom) for all other H atoms.

3. Results and discussion

Our interest in preparing pharmacologically active pyridine-related compounds (Suresh et al., 2013) led us to the title compound, derived from a 1,4-dihydropyridine, and we have undertaken X-ray crystal structure determination of this compound in order to establish its molecular conformation.

In the title compound (Fig. 1), the central pyridine ring adopts a skew-boat conformation with the puckering parameters Q = 0.127 (3) Å, θ = 87.3 (13) and φ = 198.3 (3)° (Cremer & Pople, 1975). The sums of bond angles around N4 and N5, 358.7 (2)° and 360 (2)° respectively, show that N atoms are in sp² hybridization, leading to an essentially planar imidazolidine ring. The C2/C8/N3/C9/C10 ring of the oxindole moiety is planar with r.m.s. deviation of 0.0185 (1) Å. The small tilt between the planes of the five and six-membered rings in the oxindole unit is 1.21 (1)°. The sum of the bond angles around N3 atom is 360 (1)° implying a noticeable flattening of the geometry about N3. The shorter bond lengths N3—C8 = 1.337 (4) Å and N3—C9 = 1.401 (4) Å indicate the electron donating effect of the N atom. The nitro group, N1/O1/O2, is twisted away from the mean plane of the six-membered ring, forming the dihedral angle of 8.90 (1)°. In the benzene ring (C9···C14) of the oxindole ring system, the expansion of the ipso angles at C9, C12 and C13 [121.9 (3), 120.8 (3) and 121.3 (3)°, respectively] and the contraction of the apical angles at C10, C11 and C14 [120.5 (3), 118.1 (3) and 117.3 (3)°, respectively] are caused by the fusion of the smaller ring to the six-membered benzene ring, and the strain is taken up by the angular distortion rather than by bond length distortions (Allen, 1981). The short contacts H2A···H7A (2.17 Å) and H2A···H7B (2.31 Å) result in the substantial widening of angle C7—N4—C4 to 124.9 (2)°.

The crystal structure features weak intra-molecular N—H···O interactions and N—H···O and C—H···O inter-molecular interactions. An inter-molecular N2—H2A···O3 interaction forms a chain along the c axis, while inter-molecular N5—H5···O3 and C6—H6B···O2 interactions form ring motifs R₂²(14). The solvent molecule, dimetyl sulfoxide, also takes part in the N—H···O and in the C—H···O inter-molecular interactions (Fig. 2).