Crystal structure of 2,3-diphenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one 1-oxide

In the racemic title compound, C20H15NO2S, the planes of the two phenyl substituents form dihedral angles of 48.97 (15) and 69.26 (15)° with that of the fused benzene ring of the parent benzo-thia-zine ring, while the heterocyclic thia-zine ring exhibits a screw-boat pucker. The O atom on the S atom of the ring is pseudo-axial on the thia-zine ring and trans to the 2-phenyl group. In the crystal, mol-ecules are arranged in layers in the ac plane, the layers being linked across b through inter-molecular C-H⋯O hydrogen-bonding inter-actions.