2-Phenyl-8,9,10,11-tetra-hydro-1-benzo-thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine.

In the title compound, C17H14N4S, the benzothieno moiety is fused at one end of the pyramidine ring while the triazole ring with a phenyl substituent is fused at the other side. The triazole ring is almost planar [maximum deviation = 0.0028 (3) Å] while the cyclohexane ring adopts a half-chair conformation. In the crystal, pairs of intermolecular C—H⋯N hydrogen bonds form centrosymmetric head-to-head dimers, corresponding to an R 2 2(8) graph-set motif. Further C—H⋯N interactions generate a zigzag chain of molecules along the c axis. The supramolecular assembly is consolidated by π–π stacking interactions [centroid–centroid distance = 3.445 (4) Å].

In the title compound, C 17 H 14 N 4 S, the benzothieno moiety is fused at one end of the pyramidine ring while the triazole ring with a phenyl substituent is fused at the other side. The triazole ring is almost planar [maximum deviation = 0.0028 (3) Å ] while the cyclohexane ring adopts a half-chair conformation. In the crystal, pairs of intermolecular C-HÁ Á ÁN hydrogen bonds form centrosymmetric head-to-head dimers, corresponding to an R 2 2 (8) graph-set motif. Further C-HÁ Á ÁN interactions generate a zigzag chain of molecules along the c axis. The supramolecular assembly is consolidated bystacking interactions [centroid-centroid distance = 3.445 (4) Å ].
NSB is thankful to the University Grants Commission (UGC), India, for financial assistance and the Department of Science and Technology, (DST), India, for the data-collection facility under the IRHPA-DST program.

Comment
The Chemistry of thiophenes and benzothiophenes is well documented in the literature and has drawn much attention because of their wide spectrum of biological activities (Shishoo et al., 1992). Pyrimidines and triazolopyrimidines are also associated with diverse biological activities (Bradbury et al., 1991;Elslager et al., 1981). In view of the pharmacological significance of thiophene and pyrimidine derivatives in well known drugs such as coramine (Yunosov et al., 1966), antipyrine (Blain et al., 1982) and also in continuation of our work on biologicallyactive nitrogen and sulfur heterocycles. In the title compound, the benzothieno moiety is fused at one end of the pyramidine ring and the triazole ring with a phenyl substituent is fused at the other side. The fused triazole-pyrimidine-benzotheino and the phenyl ring is coplanar with the dihedral angle 2.584 (3)°.
The triazole ring is essentially planar similar to those reported earlier (Belcher & Squattrito, 2006;Buzykin et al., 2008) with maximum deviation of atomsfrom their mean statistical planes being 0.0028 (3) Å. The N(1), atom of the triazole ring is in planar trigonal configuration similar to those reported earlier (Lipson et al., 2006). The N(1)-N(2) bond length in the triazole ring is shorter {1.362 (4)Å} than the distance characteristic of a single N-N bond (1.47 Å). The N-C and N-N distances in the triazole ring vary from 1.36 (2) Å to 1.38 (4) Å respectively. The cyclohexene ring is in half-chair conformation. The plane calculation shows that the atoms C10 and C11 deviate from the mean plane C7/C8/C9/C12 constituting the ring by -0.358 (4)Å and 0.302 (4) Å,respectively, indicating that the conformation of the ring is that of a half-chair, with the atoms C10 and C11 being displaced by this overall planarity of the rest of the ring. The ring puckering parameters for the cyclohexene ring in the title compound are Q(2) = 0.3816 (3)Å, φ(2) = 23.08 (5)° and θ= 129.07 (4)° respectively. In most of the benzotheino ring systems the cyclohexyl ring adopts half-chair conformation (Akkurt et al., 2008;Harrison et al., 2006). The crystal structure is stabilized by two C-H···N intermolecular interactions. One of the C-H···N interaction links the molecules into head-head centrosymmetric dimers corresponding to graph set notation R 2 2 (8) (Bernstein et al., 1995) (Fig 2), while the other C-H···N interaction interaction generates chain of molecules in a zig-zag tape like pattern along c axis (Fig 2). Additionally, the supramolecular assembly is further stabilized by π-π stacking interaction between the pyrimidine and phenyl rings. The C2-C4 (-x -1,1 -y,1 -z) disposed at a distance of 3.445 (4)Å.

Experimental
A solution of 2-Amino-4,5,6,7-tetrahydro-benzo[b]thiophene-3-carbonitrile (1.78 g, 10 mmole) in triethylorthoformate (12 ml) was heated under reflux for 18 h; excess triethylorthoformate was removed under pressure. The residue was treated with petroleum ether. Solid that separated was filtered and recrystallized with petroleum ether to afford light brown crystals of N- 5,6,thiophen-2-yl)-formimidic acid ethyl ester. 0.234 g, 1 mmole of this mixture and benzoic acid hydrazide (0.136 g, 1 mmole) was stirred at room temperature in toluene (5 ml) and then AcOH (0.06 g,1 mmole) was added and refluxed further till the completion of the reaction. The reaction mixture was then washed with water and dried over sodium sulfate. Toluene was removed under pressure to get analytically pure product. Yield 74%; mp; 196-198° C.

Refinement
The H atoms were placed at calculated positions in the riding model approximation with aromatic C-H = 0.97 Å, heterocyclic C-H = 0.93 Å, and U iso (H) = 1.2U eq (N/C). Fig. 1. ORTEP (Farrugia, 1997) view of the title compound, showing 50% probability ellipsoids and the atom numbering scheme.