4′-tert-Butyl-5-chloro-3H-spiro[1,3-benzothiazole-2,1′-cyclohexane]

In the title compound, C16H22ClNS, the nine-membered 2,3-dihydro-1,3-benzothiazole ring system is essentially planar, with a maximum deviation of 0.025 (2) Å for the N atom. Its plane is almost perpendicular to the main plane of the substituted cyclohexane ring, which adopts a chair conformation. In the crystal, the molecules are linked by C—H⋯π interactions.

In the title compound, C 16 H 22 ClNS, the nine-membered 2,3dihydro-1,3-benzothiazole ring system is essentially planar, with a maximum deviation of 0.025 (2) Å for the N atom. Its plane is almost perpendicular to the main plane of the substituted cyclohexane ring, which adopts a chair conformation. In the crystal, the molecules are linked by C-HÁ Á Á interactions.  (1987). For details of ring-puckering analysis, see: Cremer & Pople (1975 Table 1 Hydrogen-bond geometry (Å , ).

Comment
The condensation of aldehydes and ketones with 2-aminothiophenoles lead to benzothiazolines and spirobenzothiazolines which are reported to exhibit antitubercular (Palmer et al., 1971), analgesic (Coudert et al., 1988 and antioxidant (Karalı et al., 2010) properties. The reactivity of cyclic ketones towards 2-aminothiophenoles has also been examined and the structure of the end products has been discussed (Aryai et al., 1976;Coudert et al., 1988;Akkurt et al., 2010;Karalı et al., 2010). Prompted by the above observations, we report here the synthesis, spectroscopic and crystal structure of the title compound.

Experimental
A mixture of 2-amino-4-chlorothiophenol (0.01 mol) and 4-tert-butylcyclohexanone (0.01 mol) in absolute ethanol (50 ml) was refluxed on a water bath for 8 h. The solvent was evaporated in a crystallizing dish at room temperature and the residue was recrystallized twice from ethanol, giving X-ray quality crystals

Refinement
The NH H atom was located in a difference Fourier map and freely refined. C-bound H atoms were placed in calculated positions and treated as riding atoms : C-H = 0.93, 0.96, 0.97 and 0.98 Å, for the aromatic, methyl, methylene and methine H atoms, respectively, with U iso (H) = xU eq (C), x = 1.5 for methyl H atoms and = 1.2 for other H atoms.   The crystal packing of the title compound viewing along b axis [H atoms have been omitted for clarity].

4′-tert-Butyl-5-chloro-3H-spiro[1,3-benzothiazole-2,1′-cyclohexane]
Crystal data Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.