Methyl 2-amino-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate

Abstract

Key indicatorsSingle-crystal X-ray study T = 293 K Mean '(C±C) = 0.008 A Ê R factor = 0.078 wR factor = 0.190 Data-to-parameter ratio = 13.3For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2004 International Union of Crystallography Printed in Great Britain ± all rights reservedThe molecule of the title compound, C 10 H 13 NO 2 S, is planar. The crystal structure is stabilized by intra-and intermolecular NÐHÁ Á ÁO hydrogen bonds. Comment2-Aminothiophenes are a useful class of compounds because they display different biological properties, such as antitubercular, bacteriostatic and antifungal activities (Nakanishi et al., 1970). The structure of the title compound, (I), is composed of a thiophene ring substituted by a 2-amino group and a 3-methyl ester group. The molecule is planar (Fig. 1). The terminal ester group lies in the plane of the thiophene ring system, the torsion angle C10ÐO2ÐC9ÐC2 being 178.0 (4) .The carbonyl group has a cis orientation with respect to the C2 C3 double bond. This leads to a strong intramolecular hydrogen bond (Table 1) between one of the H atoms, viz. H2N of the amino group, and the O atom of the carbonyl group. The other H atom, H1N, is involved in molecular chains along the c axis (Fig. 2). ExperimentalThe title compound, (I), was synthesized by the Gewald reaction (Gewald et al., 1966) by mixing cyclohexanone (0.04 mol), ethyl cyanoacetate (0.04 mol), sulfur (0.04 mol) and 40 ml of ethanol and stirring the mixture at 325 K for 1 h, with dropwise addition of 4 ml of dimethylamine to yield the ester, followed by alkaline hydrolysis View of the molecule of (I), drawn with 50% probability displacement ellipsoids. The hydrogen bond is shown as dashed lines.

6-Methyl-N'-(1-methylethylidene)imidazo[2,1-b][1,3]thiazole-5-carbohydrazide monohydrate

“…The mean C-S bond length [1.729 (2) Å ] is shorter than distances reported for similar molecules [1.739 (5) Å (Vasu et al, 2004) and 1.736 (2) Å (Liu et al, 2003)]. The other bond lengths and angles are comparable with literature values (Allen et al, 1987).…”

N-(2,2-Dimethyl-4-oxo-1,3-thiazolidin-3-yl)-6-methylimidazo[2,1-b][1,3]thiazole-5-carboxamide monohydrate

“…The mean C-S bond length [1.7588 (5) Å ] is longer than distances reported for similar molecules [1.729 (2) (Akkurt et al, 2005) and 1.739 (5) Å (Vasu et al, 2004)]. The other bond lengths and angles are in agreement with expected values (Allen et al, 1987).…”

N-(X-Methylphenyl)-2-{(Z)-[(2,3,4-trimethoxyphenyl)methylidene]amino}-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide, whereX= 2 and 3

“…This is further corroborated by the fact that the bond lengths corre- sponding to the imine and carboxamide groups are significantly different: in (I), the C5-N1, C4-N2 and C13-N2 bond lengths are 1.351 (2), 1.3889 (18) and 1.2770 (19) Å , respectively, while in (II) the corresponding values are 1.355 (2), 1.389 (2) and 1.274 (2) Å . Similar bond lengths have been reported for analogous systems (Vasu et al, 2003(Vasu et al, , 2004aKumar et al, 2005). The dihedral angles formed by the m-toluidine ring in (I) and o-toluidine ring in (II) with the plane of the thiophene ring are 11.39 (6) and 48.74 (6) for (I) and (II), respectively.…”

“…The bond angle C9-C10-C11 in (I) and C6-C7-C8 in (II) are 118.16 (17) and 116.98 (18) , respectively, which deviate from the ideal value of 120 on account of the electron-releasing inductive effect of the methyl group. Similar variations in bond angles have been observed in 2-[(E)-(4chlorophenyl)methyleneamino]-N-(X-methylphenyl)-4,5,6,7tetrahydro-1-benzothiophene-3-carboxamide, where X = 2 or 3 (Vasu et al, 2004a), and in 2-{[(E)-(4-methoxyphenyl)methylene]amino}-N-(3-methylphenyl)-4,5,6,7-tetrahydro-1benzothiophene-3-carboxamide and N-(4-methylphenyl)-2-{[(E)-(4-methylphenyl)methylene]amino}-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide (Vasu et al, 2004b). Similarly, the bond angles C4-N2-C13 (around the imine N atom) and C5-N1-C6 (around the amide N atom) are 119.94 (13) and 127.79 14, respectively, in (I), and 121.83 (14) and 123.96 (13) , respectively, in (II).…”

“…Various ligands based on the benzo[b]thiophene molecular framework, in an appropriately substituted form, have demonstrated moderate to strong binding affinity for the oestrogen receptor (Jones et al, 1984;Palkowitz et al, 1997). In view of the clinical applications of these classes of compounds, single-crystal structure determinations have been performed on a series of biologically active thiophene-3-carboxamide derivatives (Vasu et al, 2003(Vasu et al, , 2004a(Vasu et al, ,b, 2005(Vasu et al, , 2008. In the majority of these structures, the invariant molecular skeleton comprises the N-phenyl-2-{[(1E)-phenylmethylidene]amino}-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide unit.…”