2,3-Diphenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-one

In the racemic title compound, C19H14N2OS, the two phenyl substituents on the 1,3-thiazine ring are almost perpendicular to the pyridine ring which is fused to the thiazine ring [inter-ring dihedral angles = 87.90 (8) and 85.54 (7)°]. The dihedral angle between the two phenyl rings is 75.11 (7)°. The six-membered thiazine ring has an envelope conformation with the ortho-related C atom forming the flap. The crystals exhibit face-to-edge aromatic-ring interactions with the nearest C—H⋯C distance equal to 3.676 (3) Å.

In the racemic title compound, C 19 H 14 N 2 OS, the two phenyl substituents on the 1,3-thiazine ring are almost perpendicular to the pyridine ring which is fused to the thiazine ring [interring dihedral angles = 87.90 (8) and 85.54 (7) ]. The dihedral angle between the two phenyl rings is 75.11 (7) . The sixmembered thiazine ring has an envelope conformation with the ortho-related C atom forming the flap. The crystals exhibit face-to-edge aromatic-ring interactions with the nearest C-HÁ Á ÁC distance equal to 3.676 (3) Å .
In the racemic title compound, C 19 H 14 N 2 OS (Fig. 1), the two phenyl substituents on the 1,3-thiazine ring are almost perpendicular to the pyridine ring which is fused to the thiazine ring [pyridyl to benzene inter-ring dihedral angles are 87.90 (8) and 85.54 (7)°]. The dihedral angle between the two benzene rings is 75.11 (7)°. The six-membered thiazine ring has an envelope conformation with the ortho-related carbon (C7) forming the flap. In the crystal, no formal intermolecular hydrogen bonds are present but face-to-edge interactions between the aromatic rings are found (Fig. 2).

Experimental
A two-necked 25 ml round bottom flask was oven-dried, cooled under N 2 , and charged with a stirring bar and N-benzylideneaniline (1.087 g, 6 mmol). Tetrahydrofuran (2.3 ml) was added, the solid dissolved, and the solution was stirred.

Refinement
The C-bound H atoms were geometrically placed with C-H = 0.93-0.97 Å, and refined as riding with U iso (H) = 1.2U eq (C).

Figure 1
An ORTEP view of the title comound. Thermal ellipsoids are drawn at the 50% probability level.  Crystal packing in the unit cell.

2,3-Diphenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-one
Crystal data C 19 H 14 N 2 OS M r = 318.38 Triclinic, P1 Hall symbol: -P 1 a = 9.069 (7) Å b = 9.772 (7) Å c = 10.150 (7) Å α = 80.320 (11) where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 0.34 e Å −3 Δρ min = −0.28 e Å −3 Special details Experimental. Absorption correction: SADABS (Sheldrick, 2004) was used for absorption correction. R int was 0.0331 before and 0.0128 after correction. The ratio of minimum to maximum transmission is 0.8482. The λ/2 correction factor is 0.0015. The data collection nominally covered a full sphere of reciprocal space by a combination of 4 sets of ω scans each set at different φ and/or 2θ angles and each scan (10 s exposure) covering -0.300° degrees in ω. The crystal to detector distance was 5.82 cm. 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.