Crystal structure of ethyl 5-acetyl-2-{[(di­methyl­amino)­methyl­idene]amino}-4-methyl­thio­phene-3-carboxyl­ate

N L Prasad; M S Krishnamurthy; H Nagarajaiah; Noor Shahina Begum

doi:10.1107/S2056989015016217

. 2015 Sep 17;71(Pt 10):o762–o763. doi: 10.1107/S2056989015016217

Crystal structure of ethyl 5-acetyl-2-{[(dimethylamino)methylidene]amino}-4-methylthiophene-3-carboxylate

N L Prasad ^a, M S Krishnamurthy ^a, H Nagarajaiah ^a, Noor Shahina Begum ^a,^*

PMCID: PMC4647409 PMID: 26594465

Abstract

In the title thiophene derivative, C₁₃H₁₈N₂O₃S, the dihedral angles between the thiophene ring and the [(dimethylamino)methylidene]amino side chain (r.m.s. deviation = 0.009 Å) and the –CO₂ ester group are 3.01 (16) and 59.9 (3)°, respectively. In the crystal, inversion dimers linked by pairs of C—H⋯O hydrogen bonds generate R ₂ ²(16) loops. The dimers are linked by another weak C—H⋯O interaction, forming chains along [001]. In addition, weak C—H⋯π interactions are observed, which link the chains into (001) layers.

Keywords: crystal structure, thiophene derivative, hydrogen bonding, C—H⋯π interactions

Related literature

For background to the applications of thiophene derivatives, see: Sabnis et al. (1999 ▸). For a related structure, see: Mukhtar et al. (2010 ▸). For further synthetic details, see: Gewald et al. (1966 ▸). graphic file with name e-71-0o762-scheme1.jpg

Experimental

Crystal data

C₁₃H₁₈N₂O₃S
M _r = 282.35
Orthorhombic,
a = 12.218 (3) Å
b = 7.332 (2) Å
c = 30.923 (8) Å
V = 2769.9 (13) Å³
Z = 8
Mo Kα radiation
μ = 0.24 mm⁻¹
T = 100 K
0.29 × 0.26 × 0.10 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1998 ▸) T _min = 0.958, T _max = 0.963
15478 measured reflections
3012 independent reflections
2140 reflections with I > 2σ(I)
R _int = 0.076

Refinement

R[F ² > 2σ(F ²)] = 0.058
wR(F ²) = 0.173
S = 1.19
3012 reflections
177 parameters
H-atom parameters constrained
Δρ_max = 0.52 e Å⁻³
Δρ_min = −0.34 e Å⁻³

Data collection: SMART (Bruker, 1998 ▸); cell refinement: SAINT-Plus (Bruker, 1998 ▸); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▸) and CAMERON (Watkin et al., 1996 ▸); software used to prepare material for publication: WinGX (Farrugia, 2012 ▸).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989015016217/hb7483sup1.cif

e-71-0o762-sup1.cif^{(18.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015016217/hb7483Isup2.hkl

e-71-0o762-Isup2.hkl^{(144.9KB, hkl)}

Click here for additional data file.^{(5.7KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015016217/hb7483Isup3.cml

Click here for additional data file.^{(1.2MB, tif)}

. DOI: 10.1107/S2056989015016217/hb7483fig1.tif

The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.

Click here for additional data file.^{(1.7MB, tif)}

. DOI: 10.1107/S2056989015016217/hb7483fig2.tif

Unit cell packing of the title compound showing intermolecular C—H⋯O interactions with dotted lines. H-atoms not involved in hydrogen bonding have been excluded.

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

. DOI: 10.1107/S2056989015016217/hb7483fig3.tif

Unit cell packing depicting C—H⋯π interactions with dotted lines.

CCDC reference: 1421360

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

Table 1. Hydrogen-bond geometry (, ).

Cg is the centroid of the C2/C3/C4/C5/S1 ring.

DHA	DH	HA	D A	DHA
C9H9AO2ⁱ	0.99	2.45	3.270(3)	139
C11H11O1ⁱⁱ	0.95	2.47	3.312(4)	147
C7H7C Cg ⁱⁱⁱ	0.98	2.86	3.693(2)	143

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

Acknowledgments

NLP thanks the University Grants Commission (UGC), India for a CSIR–NET fellowship and MSK thanks the UGC for a UGC–BSR Meritorious fellowship.

supplementary crystallographic information

S1. Comment

Thiophene belongs to a class of heterocyclic compounds containing a five membered ring made up of one sulfur as heteroatom, that are widely used as building blocks in many agrochemicals and pharmaceuticals. 2-Aminothiophenes attract special attention because of their applications in pharmaceuticals, agriculture, pesticides and dyes (Sabnis et al., 1999). The most convergent and well established classical approach for the preparation of 2-aminothiophenes is Gewald's method (Gewald et al., 1966), which involves the multicomponent condensation of a ketone with an activated nitrile and elemental sulfur in the presence of diethylamine as a catalyst. Herein, we report the structure of the title compound, (I).

The molecular structure of the compound is shown in Fig. 1. In the title compound, C₁₃H₁₈N₂O₃S, a thiophene derivative with dimethylamino- methyleneamino, acetyl, methyl and ethyl carboxylate substituents attached to a central thiophene ring. The thiophene ring and all the substituents are almost planar except the carboxyl group (C10/C9/O3/C8), it is slightly deviating from the plane at -83.474 (3)°. The carbonyl group of the exocyclic ester at C3 and acetyl at C5 adopts a trans orientation with C3=C2 and C5=C4 double bond respectively. The crystal structure features C—H···O interactions. The C11—H11···O1 hydrogen bonds resulting in a centrosymmetric head to head dimer with graph set R²₂(16) notation, which are in turn linked by another weak C9—H9A···O2 interactions to form chains of rings along [001] (Table.1; Fig. 2). In addition, weak C—H···π interactions of the type C7—H7C···Cg [Cg being the centroid of the thiophene ring (C2/C3/C4/C5/S1)] link the chains into layers parallel to (001) with a distance 2.864 Å is also observed (Fig. 3).

S2. Experimental

Step-1: 3.3 g of cyano ethyl acetate was weighed and transferred to RB flask and 5 g of acetyl acetone and 10 to 15 ml of ethanol were added to it. The whole mixture was stirred for 10 min. After stirring 1.6 g of elemental sulfur was added to the mixture and cold condition was maintained by using crushed ice. Later 5 ml of diethyl amine was added drop by drop the solution changes its color to red. After the completion of addition the solution was again kept for stirring (10 min). Ice pack was removed and stirring was continued for about an hour. The precipitated product (1) was filtered, dried and recrystallized from ethanol (yield: 68%, m.p. 430 K)

Step-2: A mixture of compound 1 (10 mmol) and DMF—DMA (5 ml) was stirred at room temperature for 30 minutes. To this was added ethanol and kept in room temperature to give a solid product (title compound) that was collected by filtration. The compound was recrystallized by slow evaporation from ethanol, yielding single crystals suitable for X-ray diffraction studies.