{2-[(2-Hydroxybenzylidene)amino]-4,5,6,7-tetrahydro-1-benzothiophen-3-yl}(phenyl)methanone

In the title compound, C22H19NO2S, the cyclohexene ring adopts a slightly distorted half-chair conformation. The dihedral angles between the mean planes of the thiophene ring and the phenyl and 2-hydroxyphenyl rings are 70.4 (5) and 12.1 (9)°, respectively. The phenyl and 2-hydroxyphenyl rings are twisted with respect to one another by 81.0 (6)°. A short intramolecular O—H⋯N hydrogen bond is observed. In the crystal, weak C—H⋯O interactions link the molecules into zigzag chains diagonally along [100] .

In the title compound, C 22 H 19 NO 2 S, the cyclohexene ring adopts a slightly distorted half-chair conformation. The dihedral angles between the mean planes of the thiophene ring and the phenyl and 2-hydroxyphenyl rings are 70.4 (5) and 12.1 (9) , respectively. The phenyl and 2-hydroxyphenyl rings are twisted with respect to one another by 81.0 (6) . A short intramolecular O-HÁ Á ÁN hydrogen bond is observed. In the crystal, weak C-HÁ Á ÁO interactions link the molecules into zigzag chains diagonally along [100] .

Comment
Thiophene derivatives have been reported to exhibit a broad spectrum of biological properties such as anti-inflammatory, analgesic, antidepressant, antimicrobial and anticonvulsant activities (Molvi et al., 2007;Rai et al., 2008;Asthalatha et al. , 2007). 2-Aminothiophene derivatives have been used in a number of applications as pesticides, dyes and pharmaceuticals. Reviews of the synthesis and properties of these compounds have been reported (Sabnis et al. 1999;Puterová et al. 2010). Substituted 2-aminothiophenes are active as allosteric enhancers at the human A1 adenosine receptor (Cannito et al.,1990;Nikolakopoulos et al., 2006;Lütjens et al., 2005). Schiff base compounds are an important class of compounds both synthetically and biologically. These compounds also show biological activities including antibacterial, antifungal, anticancer and herbicidal activities (Desai et al., 2001;Karia & Parsania, 1999;Samadhiya & Halve, 2001;Singh & Dash, 1988). Furthermore, Schiff bases are utilized as starting materials in the synthesis of compounds of industrial (Aydogan et al., 2001) and biological interest such as β-lactams (Taggi et al., 2002). The crystal and molecular structures of two 2-aminothiphenes have been previously reported by our group (Kubicki et al., 2012). In continuation of our work on 2-aminothiophenes and Schiff bases, we report here the crystal structure of the title compound, (I), C 22 H 19 NO 2 S.

Experimental
To a solution of (2-Amino-4,5,6,7-tetrahydro-benzo[b]thiophen-3-yl)-phenyl-methanone (200 mg, 0.79 mmol) in 10 ml of methanol an equimolar amount of 2-hydroxybenzaldehyde (97 mg, 0.79 mmol) was added dropwise with constant stirring. The mixture was refluxed for 3 hours. A yellow precipitate was obtained. The reaction completion was confirmed by thin layer chromatography. The resulting precipitate was filtered and dried at room temperature overnight. The solid was recrystallized from dichloromethane and the crystals were used as such for x-ray diffraction studies.

Refinement
All of the H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.93Å (CH); 0.99Å (CH 2 ) or 0.82Å (OH). Isotropic displacement parameters for these atoms were set to 1.2 (CH, CH 2 ) or 1.5 (OH) times U eq of the parent atom. The idealised tetrahedral OH was refined as a rotating group.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.