Crystal structure of ethyl 1′,1′′-dimethyl-2′′,3-dioxo-3H-di­spiro­[benzo[b]thio­phene-2,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxyl­ate

M P Savithri; M Suresh; R Raghunathan; R Raja; A SubbiahPandi

doi:10.1107/S2056989015002042

. 2015 Feb 4;71(Pt 3):o142. doi: 10.1107/S2056989015002042

Crystal structure of ethyl 1′,1′′-dimethyl-2′′,3-dioxo-3H-dispiro[benzo[b]thiophene-2,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxylate

M P Savithri ^a, M Suresh ^b, R Raghunathan ^b, R Raja ^c, A SubbiahPandi ^c,^*

PMCID: PMC4350758 PMID: 25844216

Abstract

In the title compound, C₂₃H₂₂N₂O₄S, the pyrrolidine ring has an envelope conformation with the spiro C atom, shared with the indoline ring system, as the flap. The mean planes of the benzothiophene and indoline ring systems are inclined to the mean plane of the pyrrolidine ring by 88.81 (8) and 79.48 (8)°, respectively, and to each other by 68.12 (5)°. In the crystal, molecules are linked via C—H⋯O hydrogen bonds, forming chains propagating along [001].

Keywords: crystal structure, dispiro, benzothiophene, pyrrolidine, indole, C—H⋯O hydrogen bonds.

Related literature

For various biological activities of indole derivatives, see: Harris & Uhle (1960 ▸); Ho et al. (1986 ▸); Stevenson et al. (2000 ▸). For the crystal structures of two very similar compounds, see: Savithri et al. (2014 ▸). graphic file with name e-71-0o142-scheme1.jpg

Experimental

Crystal data

C₂₃H₂₂N₂O₄S
M _r = 422.49
Monoclinic,
a = 23.7049 (11) Å
b = 8.2632 (3) Å
c = 22.1003 (8) Å
β = 102.337 (2)°
V = 4229.0 (3) Å³
Z = 8
Mo Kα radiation
μ = 0.19 mm⁻¹
T = 293 K
0.35 × 0.30 × 0.30 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▸) T _min = 0.896, T _max = 0.910
22087 measured reflections
4621 independent reflections
3869 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.038
wR(F ²) = 0.105
S = 1.03
4618 reflections
275 parameters
H-atom parameters constrained
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.20 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 ▸, 2015 ▸); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▸); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▸).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989015002042/su5065sup1.cif

e-71-0o142-sup1.cif^{(23.8KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015002042/su5065Isup2.hkl

e-71-0o142-Isup2.hkl^{(221.7KB, hkl)}

Click here for additional data file.^{(1.3MB, tif)}

. DOI: 10.1107/S2056989015002042/su5065fig1.tif

The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Click here for additional data file.^{(2.6MB, tif)}

b . DOI: 10.1107/S2056989015002042/su5065fig2.tif

The crystal packing of the title compound viewed along the b axis. Dashed lines shows the intermolecular C—H⋯O hydrogen bonds. H atoms not involved in hydrogen bonding have been omitted for clarity.

CCDC reference: 1046459

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

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C5H5O3ⁱ	0.93	2.46	3.212(2)	138

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Symmetry code: (i) Inline graphic .

Acknowledgments

MPS and ASP thank Dr Babu Vargheese, SAIF, IIT, Madras, India, for his help with the data collection.

supplementary crystallographic information

S1. Comment

Indole compounds can be used as bioactive drugs (Stevenson et al., 2000). Indole derivatives exhibit antiallergic, central nervous system depressant and muscle relaxant properties (Harris & Uhle, 1960; Ho et al., 1986). In view of this biological importance, the crystal structure of the title compound was determined and the results are presented here.

The X-ray analysis confirms the molecular structure and atom connectivity as illustrated in Fig. 1. The geometric parameters of the title molecule agrees well with those reported for similar structures (Savithri et al., 2014).

The five membered ring (N1/C1/C6-C8) in the indole moiety adopts an envelope conformation with the C8 as the flap atom [puckering parameters q₂ = 0.0888 (2)Å and φ₂ = 284.2 (1)°] and the pyrrolidine ring (N2/C8-C11) exhibits a twisted conformation [puckering parameters, q₂ = 0.4626 (2)Å and φ₂ = 233.4 (2)°]. The bond length C12-O2 = 1.211 Å indicates a keto group in the benzothiophene. The sum of angles at N2 of the pyrrolidine ring (339°) is in accordance with sp³ hybridization and the sum of angles at N1 of the indole moiety (359°) is in accordance with sp² hybridization.

The pyrrolidine ring (N2/C8-C11) is perpendicular with benzothiophene (C11-C18/S1) oriented at a dihedral angle of 88.81 (8)° and is oriented with indole ring (N1/C1-C8) at a dihedral angle of 79.48 (8)°. The thiophene ring (C11-C14/S1) makes dihedral angles of 87.98 (8)° and 67.14 (6)° with pyrrolidine (N2/C8-C11) and indole (N1/C1-C8) rings, respectively.

In the crystal, hydrogen-bonded chains running along [001] are generated by connecting neighbouring molecules via C-H···O hydrogen bonds (Table 1 and Fig. 2).

S2. Experimental

(E)-ethyl 2-(3-oxobenzo[b]thiophen-2(3H)-ylidene) acetate (1.0 mmol), N-methyl isatin (1.1 mmol) and sarcosine (1.1 mmol) were refluxed in methanol (20ml) until completion of the reaction monitored by TLC analysis. After completion of the reaction the solvent was evaporated under reduced pressure. The crude reaction mixture was dissolved in dichloromethane (2 × 50 ml) and washed with water followed by brine solution. The organic layer was separated and dried over sodium sulfate. After filtration the organic solvent was evaporated under reduced pressure. The product was separated by column chromatography using hexane and ethyl acetate (9:1) as an eluent to give a colourless solid. The product was dissolved in chloroform (3 ml) and heated for 2 min. The resulting solution was subjected to crystallization by slow evaporation of the solvent giving in single crystals suitable for X-ray crystallographic studies.