Crystal structure of 2-(4-methylphenyl)-4H-1,3-benzothiazine

In the title compound, C15H13NS, the thiazine ring adopts a boat conformation. The dihedral angle between the planes of the benzene ring of the benzothiazine unit and the tolyl ring is 19.52 (9)°. In the crystal, molecules are linked by weak C—H⋯π interactions into a tape structure along the b-axis direction.


S1. Comment
Benzothiazines have been found to posses versatile biological activities, such as analgesic (Gupta et al., 2002), anti bacterial (Zia-ur-Rehman et al., 2006) and antioxidant activities (Ahmad et al., 2010). Also, benzothiazine derivatives have shown activities for the treatment of asthmatic therapy (Lazzeri et al., 2001). Recently, 1,2-benzothiazine-1,1dioxide and its derivatives were reported as aldose reductase inhibitors (Parveen et al., 2014). With this potential background of benzothiazine derivatives, we have synthesized the title compound to study its crystal structure.

S2. Experimental
4-Methyl-N-[(phenylthio)methyl]benzamide was heated with POCl 3 (10 ml) on an oil bath for 1 h. The reaction mixture was cooled by treated with ice, neutralized with Na 2 CO 3 , and extracted with dichloromethane. The combined extracts were dried (Na 2 SO 4 ) and solvent was evaporated off. The residue was recrystalized from hot ethanol to get crystals of the title compound.

S3. Refinement
All H atoms were positioned geometrically and allowed to ride on their parent atom, with C-H = 0.93-0.97 Å, and with U iso (H) = 1.2-1.5U eq (C).

Figure 1
The molecular structure of the title compound with 50% probability displacement ellipsoids. H atoms are drawn as spheres of arbitrary radii.

Figure 2
A packing diagram of the title compound viewed along the b axis.  (7) Special details 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.