(S)-4-Phenyl-2-(1,2,3,4-tetra­hydro­isoquinolin-3-yl)-1,3-thia­zole

In the title compound, C₁₈H₁₆N₂S, the N-containing ring adopts a half-chair configuration. The crystal packing features C—H...N contacts. There is no π–π stacking within the crystal structure.

Ethyl 2-(3,5-dimethyl-1,1-dioxo-2H-1λ⁶,2,6-thia­diazin-4-yl)benzoate

In the title compound, C₁₄H₁₆N₂O₄S, the thia­diazine ring is in a half-boat conformation. The aromatic ring deviates from the plane of this moiety at an angle of 74.6 (2)°. The structure displays inter­molecular N—H...O hydrogen bonding [N...O = 2.8157 (16) Å], creating ribbons along the [010] axis. There are also weak C—H...O inter­actions in the crystal but no π–π stacking.

2-(3,5-Dimethyl-1,1-dioxo-2H-1λ⁶,2,6-thia­diazin-4-yl)benzoic acid

In the title mol­ecule, C₁₂H₁₂N₂O₄S, the S atom of the thia­diazine ring deviates by 0.5104 (4) Å from the mean plane of the other five atoms [largest deviation = 0.0623 (15) Å] giving a slightly distorted sofa conformation. The carb­oxy H atom was refined as disordered over two sets of sites with refined occupancies of 0.58 (2) and 0.48 (2). This corresponds to rotational disorder of the C=O and O—H groups about the attached C—C bond. In the crystal, O—H...O and N—H...O hydrogen bonds connect the mol­ecules into chains along [110].

Methyl 2-(2,3,5-trimethyl-1,1-dioxo-2H-1λ⁶,2,6-thia­diazin-4-yl)benzoate

There are two mol­ecules, A and B, in the asymmetric unit of the title compound, C₁₄H₁₆N₂O₄S, which is the first example reported in this family of compounds in which the Nsp³ atom of the thia­diazine ring is methyl­ated. The thia­diazine rings adopt shallow envelope conformations, with the S atoms displaced by 0.319 (12) and 0.182 (12) Å from the mean planes of the other ring atoms in mol­ecules A and B, respectively. The dihedral angles between the thia­diazine mean planes (excluding S) and the attached benzene rings are 86.8 (3) and 86.7 (3)° for mol­ecules A and B, respectively.