3-Amino-4-(1,3-benzoxazol-2-yl)-5-(cyclohexylamino)thiophene-2-carbonitrile

In the title compound, C18H18N4OS, the cyclohexyl ring adopts a chair conformation. The other rings of this compound lie almost in the same plane, with a mean deviation of 0.03 (2) Å from the least-squares plane defined by the 14 constituent atoms. There are intramolecular N—H⋯N and N—H⋯O hydrogen bonds, as well as intermolecular N—H⋯N hydrogen bonds, which link the molecules into centrosymmetric dimers.

In the title compound, C 18 H 18 N 4 OS, the cyclohexyl ring adopts a chair conformation. The other rings of this compound lie almost in the same plane, with a mean deviation of 0.03 (2) Å from the least-squares plane defined by the 14 constituent atoms. There are intramolecular N-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds, as well as intermolecular N-HÁ Á ÁN hydrogen bonds, which link the molecules into centrosymmetric dimers.
All bond lengths are normal and are comparable with those reported for a similar structure (Belhouchet et al., 2012).
There are intramolecular N-H···N and N-H···O hydrogen bonds as well as intermolecular N-H···N hydrogen bonds which link the molecules into centrosymmetric dimers ( Figure 2 and Table 1). There are no other intermolecular interactions present.

Experimental
Previously, we investigated the reaction of benzoxazole with active methylene compounds and aldehyde in alkaline medium, which has proved to be a convenient route for the synthesis of pyridobenzoxazole ring systems (Youssef et al.,2011). Now, we have extended our synthetic program to the synthesis of thiophenes ring system, utilizing benzoxazol-2-cyanomethyle as a key starting material.
To a cold suspension of potassium tertio-butylate (25 mmol) in THF (30 ml) benzoxazol-2-cyanomethyl was added (22 mmol) and followed by cyclohexyl isothiocyanate (22 mmol). The mixture was stirred overnight at room temperature and treated with the chloroacetone (22 mmol), stirring was continued for 4 h. The reaction mixture was poured onto ice cold water. Acidification using dilute HCl until the medium becomes acidic gave the synthesized solid product which was filtered off, washed with water, dried and recrystallized from aqueous ethanol solution to give single-crystal suitable for the X-ray diffraction.)

Figure 1
The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radius.   Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites H atoms treated by a mixture of independent and constrained refinement w = 1/[σ 2 (F o 2 ) + (0.0502P) 2 + 0.4702P] where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.17 e Å −3 Δρ min = −0.17 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0009 (2) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq S1 0.55009 (