5-Amino-5′-bromo-6-(4-methyl­benzo­yl)-8-nitro-2,3-di­hydro-1H-spiro­[imidazo[1,2-a]pyridine-7,3′-indolin]-2′-one including an unknown solvate

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

doi:10.1107/S1600536814014391

. 2014 Jun 25;70(Pt 7):o816–o817. doi: 10.1107/S1600536814014391

5-Amino-5′-bromo-6-(4-methylbenzoyl)-8-nitro-2,3-dihydro-1H-spiro[imidazo[1,2-a]pyridine-7,3′-indolin]-2′-one including an unknown solvate

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

PMCID: PMC4120621 PMID: 25161594

Abstract

In the title compound, C₂₂H₁₈BrN₅O₄, the central six-membered ring, derived from 1,4-dihydropyridine, adopts a distorted boat conformation with a puckering amplitude of 0.197 (3) Å, the imidazole ring adopts a twisted conformation with a puckering amplitude of 0.113 (3) Å, and the oxindole moiety is planar with an r.m.s. deviation of 0.0125 Å. Two intramolecular N—H⋯O hydrogen bonds are formed, each closing an S(6) loop. In the crystal, strong N—H⋯O hydrogen bonds lead to the formation of zigzag chains along the c axis. These are consolidated in the three-dimensional crystal packing by weak N—H⋯O hydrogen bonding, as well as by C—H⋯O, C—H⋯Br and C—H⋯π interactions. A small region of electron density well removed from the main molecule was removed with the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155] following unsuccessful attempts to model it as a plausible solvent molecule. The unit-cell characteristics do not take into account this feature of the structure.

Keywords: crystal structure

Related literature

For a similar structure, see: Nagalakshmi et al. (2014 ▶). For additional conformational analysis, see: Cremer & Pople (1975 ▶). graphic file with name e-70-0o816-scheme1.jpg

Experimental

Crystal data

C₂₂H₁₈BrN₅O₄
M _r = 496.32
Monoclinic,
a = 15.5482 (9) Å
b = 14.7033 (7) Å
c = 12.1907 (6) Å
β = 101.856 (2)°
V = 2727.5 (2) Å³
Z = 4
Mo Kα radiation
μ = 1.54 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
30073 measured reflections
5962 independent reflections
4098 reflections with I > 2σ(I)
R _int = 0.035

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.114
S = 1.04
5962 reflections
289 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.41 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/S1600536814014391/tk5316sup1.cif

e-70-0o816-sup1.cif^{(23.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814014391/tk5316Isup2.hkl

e-70-0o816-Isup2.hkl^{(286KB, hkl)}

Click here for additional data file.^{(8.2KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814014391/tk5316Isup3.cml

CCDC reference: 1009067

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

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

Cg1 is the centroid of the C32–C37 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N5—H5⋯O1	0.86	2.09	2.608 (2)	118
N2—H2B⋯O4	0.86	1.87	2.518 (2)	131
N3—H3⋯O4ⁱ	0.86	1.95	2.792 (2)	168
N5—H5⋯O3ⁱⁱ	0.86	2.36	2.961 (2)	127
C7—H7A⋯O3ⁱⁱⁱ	0.97	2.54	3.342 (3)	140
C33—H33⋯Br1^iv	0.93	2.91	3.675 (2)	141
C14—H14⋯Cg1ⁱ	0.93	2.83	3.553 (2)	135

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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

S1. Chemical context

S2. Structural commentary

Our interest in preparing pharmacologically active pyridine-related compounds (Nagalakshmi et al., 2014) led us to the title compound, derived from a 1,4-dihydropyridine. We have undertaken an X-ray crystal structure determination of this compound in order to establish its molecular conformation.

In the title compound (Fig. 1), the central six-membered ring adopts a distorted-boat conformation with the puckering parameters Q = 0.197 (3) Å and θ = 102.0 (10)° and φ = 9.1 (6)° (Cremer & Pople, 1975). The imidazole ring adopts a twisted conformation with puckering parameters Q = 0.113 (3) Å and φ₂ = 302.9 (11)° (Cremer & Pople, 1975). The oxindole moiety (C2/C8—C14/N3/O3) is planar with r.m.s. deviation of 0.0125 Å. The sum of valence angles at N2 (360 (3)°) indicates that the atom N2 is sp² hybridized. There is a partial delocalization of the lone pair of N2 towards the pyridine ring which is confirmed by the short bond length of C4–N2 = 1.324 (3) Å. The C–N and C–C bond lengths (C4–N4 = 1.361 (3) Å, N4–C5 = 1.365 (3) Å, C1–C2 = 1.523 (3) Å are shorter than the standard C–N = 1.47 Å and C–C = 1.54 Å, respectively. By contrast, the C═C bond lengths (C1═C5 = 1.383 (3) Å and C4═C3 = 1.409 (3) Å) are longer than the standard C═C bond (1.34 Å). Thus, the title compound shows that there is a homo-conjugation effect on the pyridine moiety.

In the crystal, N3—H3···O4 hydrogen bonds lead to the formation of chains along the c axis. N5—H5···O3 hydrogen bonds lead to the formation of chains along the b axis. There are further C7—H7A···O3 and C33—H33···Br1 hydrogen bonds enclosing R₂²(16) and R₂²(20) ring motifs respectively as shown in Fig. 2. The structure is further stabilized by weak C—H···π inter-molecular interactions.

S3. Supramolecular features

S4. Database survey

S5. Synthesis and crystallization

A mixture of 4-methylbenzoylacetonitrile (1.0 mmol), 5-bromoisatin (1.0 mmol) and 2-(nitromethylene)imidazolidine were dissolved in 10 ml of EtOH and triethylamine (1.0 mmol) was added and the reaction mixture was heated to reflux 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 91 %. Melting point 530 K.

S6. Refinement

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. A small region of electron density well removed from the main molecule and appearing disordered was removed with PLATON SQUEEZE [Spek (2009). Acta Cryst. D65, 148–155] following unsuccessful attempts to model it as plausible solvent molecule.