Ethyl 2-[(Z)-3-chloro­benzyl­idene]-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-1,3-thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate

In the title compound, C23H19ClN2O3S, the central pyrimidine ring is significantly puckered, assuming almost a screw boat conformation. In addition to the usual inter­molecular C—H⋯O hydrogen bonding, short intra­molecular C—H⋯S contacts and π–π stacking inter­actions [centroid–centroid distance = 3.762 (2) Å] contribute to the crystal packing

Ethyl 2-(2-acetoxy­benzyl­idene)-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-1,3-thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate1

In the title mol­ecule, C25H22N2O5S, the atoms of the thia­zolopyrimidine ring system, with the exception of the phenyl-bearing C atom [deviation = 0.177 (2) Å], are essentially planar [r.m.s deviation = 0.100 (2) °] and the mean plane of these atoms forms dihedral angles of 89.86 (10) and 7.97 (8)° with the phenyl and benzene rings, respectively. In the crystal, co-operative C—H⋯O and C—H⋯π inter­actions lead to a supra­molecular chain along the a axis. These chains are connected via π–π inter­actions [centroid–centroid = 3.7523 (13) Å]

N-(2-Oxo-2H-chromen-3-yl)benzamide

The phenyl ring in title mol­ecule, C16H11NO3, forms a dihedral angle of 7.69 (6)° with the fused ring system. The observed conformation is stabilized by intra­molecular N—H⋯O and C—H⋯O inter­actions. In the crystal, supra­molecular chains are formed along the b axis which are mediated by π–π inter­actions [centroid–centroid distance = 3.614 (2) Å]

Ethyl (2Z)-2-(3-methoxy­benzyl­idene)-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-1,3-thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate

In the title compound, C24H22N2O4S, the central pyrimidine ring is significantly puckered, assuming a conformation inter­mediate between a boat and a screw boat. The nearly planar thia­zole ring (r.m.s. deviation = 0.0258 Å) is fused with the pyriamidine ring, making a dihedral angle of 9.83 (7)°. The carboxyl group is in an extended conformation with an anti-periplanar orientation with respect to the dihydropyrimidine ring. The benzene ring linked at the chiral C atom is perpendicular to the pyrimidine ring [dihedral angle = 85.21 (8)°] whereas the phenyl ring is nearly coplanar, making a dihedral angle of 13.20 (8)°. An intra­molecular C—H⋯S hydrogen bond is observed. The crystal packing is influenced by weak inter­molecular C—H⋯π inter­actions and π–π stacking between the thia­zole and phenyl rings [centroid–centroid distance = 3.9656 (10) Å], which stack the mol­ecules along the c axis

4-{[(4Z)-5-Oxo-2-phenyl-4,5-dihydro-1,3-oxazol-4-yl­idene]meth­yl}phenyl acetate

The title mol­ecule, C18H13NO4, shows a dihedral angle between the terminal acetyl group (r.m.s. deviation = 0.0081 Å) and remaining non-H atoms (r.m.s. = 0.0734 Å) of 53.45 (7)°. The configuration about the central olefinic bond is Z and overall the mol­ecule has a U-shaped conformation. Supra­molecular chains along the b-axis direction are found in the crystal structure. These are stabilized by (C=O)⋯π(ring centroid of the 1,3-oxazole ring) inter­actions [3.370 (2) Å]

N-(3,4-Dichloro­phen­yl)-3-oxo­butanamide

In the title compound. C10H9Cl2NO2, the acetamide residue is twisted out of the phenyl ring plane by 25.40 (9)°. An intra­molecular C—H⋯O close contact is observed. The N atom of the butanamide unit forms an inter­molecular N—H⋯O hydrogen bond with the symmetry-related carbonyl O atom, inter­linking mol­ecules into a C(4) chain along [100]. Additional C—H⋯O inter­molecular inter­actions and Cl⋯Cl contacts [3.4364 (8) Å] contribute to the stability of the crystal packing