Ethyl 2-benzamido-4,5,6,7-tetra­hydro-1-benzothio­phene-3-carboxyl­ate

Asma Mukhtar; M Nawaz Tahir; Misbahul Ain Khan; Muhammad Naeem Khan

doi:10.1107/S1600536810037761

. 2010 Sep 30;66(Pt 10):o2652. doi: 10.1107/S1600536810037761

Ethyl 2-benzamido-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate

Asma Mukhtar ^a, M Nawaz Tahir ^b,^*, Misbahul Ain Khan ^a, Muhammad Naeem Khan ^c

PMCID: PMC2983258 PMID: 21587623

Abstract

The molecule of the title compound, C₁₈H₁₉NO₃S, adopts an approximately planar conformation: the thiophene and phenyl rings form a dihedral angle of 8.13 (11)° while the ethyl ester group (r.m.s. deviation = 0.0217 Å) is inclined at 1.25 (14) and 8.61 (13)°, respectively, to the thiophene and phenyl rings. An intramolecular N—H⋯O hydrogen bond with an S(6) ring motif occurs as well as an intramolecular S⋯O hypervalent interaction [S⋯O = 2.7369 (18) Å]. The cyclohexene ring adopts a half-chair conformation and is disordered over two positions with site occupation factors of 0.641 (6) and 0.359 (6). In the crystal, inversion dimers linked by pairs of O—H⋯O hydrogen bonds generate R ₂ ²(10) loops.

Related literature

For background on thiophene derivatives, see: Dupin et al. (2002 ▶); Khan & Rolim (1983 ▶); Sabnis et al. (1999 ▶). For related structures, see: Harrison et al. (2006 ▶); Yathirajan et al. (2007 ▶). For graph-set notation, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₁₈H₁₉NO₃S
M _r = 329.40
Monoclinic,
a = 8.1061 (2) Å
b = 10.6593 (3) Å
c = 19.0554 (5) Å
β = 92.500 (1)°
V = 1644.92 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.21 mm⁻¹
T = 296 K
0.25 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.953, T _max = 0.958
12204 measured reflections
2964 independent reflections
2052 reflections with I > 2σ(I)
R _int = 0.037

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.117
S = 1.01
2964 reflections
210 parameters
6 restraints
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; 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, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON.

Supplementary Material

Crystal structure: contains datablocks text, I. DOI: 10.1107/S1600536810037761/gk2302sup1.cif

e-66-o2652-sup1.cif^{(21.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810037761/gk2302Isup2.hkl

e-66-o2652-Isup2.hkl^{(142.5KB, 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
N1—H1⋯O2	0.86	2.02	2.664 (2)	131
C6—H6⋯O1ⁱ	0.93	2.44	3.242 (3)	145

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors acknowledge the provision of funds for the purchase of the diffractometer and encouragement by Dr Muhammad Akram Chaudhary, Vice Chancellor, University of Sargodha, Pakistan.

supplementary crystallographic information

Comment

Thiophenes and their condensed derivatives have been described in the literature (Khan & Rolim, 1983). Tetrahydro-1-benzothiophenes are intermediates for many useful products such as dyes and pharmaceuticals (Sabnis et al., 1999) and compounds containing thrombolytic activity (Dupin et al., 2002). The title compound (Fig. 1) has been prepared for the derivatization of other compounds.

The crystal structures of ethyl 2-acetylamino-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate (Harrison et al., 2006) and i.e. ethyl 2-(propionylamino)-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate (Yathirajan et al., 2007) have been published which are related to the title compound.

In the title compound, the heterocyclic ring A (S1/C8/C9/C10/C15) and the phenyl ring B (C1—C6) are planar. The dihedral angle between A/B is 8.13 (11)°. The ethyl ester group C (O2/C16/O3/C17/C18) is planar with r. m. s. deviation of 0.0217 Å and is inclined at 1.25 (14) and 8.61 (13)° with the rings A and B, respectively. In the title compound an S(6) ring motif (Bernstein et al., 1995) is formed due to intramolecular H-bonding of N—H···O type (Table 1, Fig. 1). Two methylene groups of the cyclohexene ring in half-chair conformation are disordered over two positions with site occupation factors of 0.641 (6) and 0.359 (6).

Experimental

Ethyl 2-amino-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate (0.3 g, 1.0 mmol) was dissolved in 10 ml of chloroform. To this solution 0.15 ml of benzoyl chloride was added and heated under reflux for 9 h. The solvent was removed and the residue was recrystallized from ethanol to affoard the colorless prism.