Crystal structure of N-[(2S,5R)-4-oxo-2,3-diphenyl-1,3-thiazinan-5-yl]acetamide 0.375-hydrate

The asymmetric unit of the title compound, C₁₈H₁₈N₂O₂S.0.375H₂O, has two independent organic molecules (A and B) and 3/4 of a water molecule distributed over three sites. In molecule A, the 1, 3-thiazine ring is in a boat conformation, with the C atoms at the 2- and 5-positions out of the plane. The angle between the two phenyl rings is 51.70 (12)°. In molecule B, the thiazine ring is in a half-chair conformation, with the S atom forming the back of the half-chair. The angle between the two phenyl rings is 84.44 (14)°. The A molecule features an intramolecular N - H⋯O hydrogen bond, which closes an S(5) ring motif. In the crystal, the corresponding N - H grouping of the B molecule participates in an intermolecular hydrogen bond to the A molecule. The A molecule participates in a C - H⋯O interaction back to the B molecule, whilst the B molecule features an intramolecular C - H⋯O link, which generates an S(10) loop.