Crystal structures of two solvated 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones

The synthesis and crystal structures of 2-(4-fluorophenyl)-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-one toluene hemisolvate (1), C₁₉H₁₃FN₂OS·0.5C₇H₈, and 2-(4-nitrophenyl)-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-one isopropanol 0.25-solvate 0.0625-hydrate (2), C₁₉H₁₃N₃O₃S·0.25C₃H₇O·0.0625H2O, are reported. Both are racemic mixtures (centrosymmetric crystal structures) of the individual compounds and incorporate solvent molecules in their structures. Compound 2 has four thiazine molecules in the asymmetric unit. All the thiazine rings in this study show an envelope pucker, with the C atom bearing the substituted phenyl ring displaced from the other atoms. The phenyl and aryl rings in each of the molecules are roughly orthogonal to each other, with dihedral angles of about 75°. The extended structures of 1 and 2 are consolidated by C-H..O and C-H..N(π), as well as T-type (C-H..π) interactions. Parallel aromatic ring interactions (π-π stacking) are observed only in 2.