5-Acetyl-4-(2-chloro­phen­yl)-6-methyl-3,4-dihydro­pyrimidine-2(1H)-thione

In the title mol­ecule, C13H13ClN2OS, the heterocyclic ring adopts a flattened boat conformation with the plane through the four coplanar atoms making a dihedral angle of 85.6 (1)° with the benzene ring, which adopts an axial orientation. The thionyl, acetyl and methyl groups all have equatorial orientations. Inter­molecular N—H⋯O, N—H⋯S and C—H⋯S hydrogen bonds are found in the crystal structure. A weak C—H⋯π inter­action involving the benzene ring also occurs

1-Methyl-3,5-bis­[(E)-(3-methyl-2-thienyl)methyl­ene]piperidin-4-one monohydrate

In the title mol­ecule, C18H19NOS2·H2O, the piperidine ring adopts an envelope conformation with the methyl substituent in an equatorial position. Each of the olefinic double bonds has an E configuration. The dihedral angle between the two thio­phene rings is 6.04 (14)°. The water mol­ecule forms two donor inter­actions, one with the carbonyl O atom and the other to the hetero N atom. The centrosymmetric {C18H19NOS2·H2O}2 pairs thus formed are linked into a supra­molecular chain via C—H⋯Owater contacts

1-Acetyl-2-r,6-c-bis­(4-chloro­phen­yl)-3-methyl-1,2,5,6-tetra­hydro­pyridin-4-yl acetate

In the title compound, C22H21Cl2NO3, the pyridine ring adopts a half-chair conformation and the 4-chloro­phenyl groups occupy axial positions. The 4-chloro­phenyl groups are almost perpendicular to the plane of the tetra­hydro­pyridine ring forming dihedral angles 84.62 (6) and 85.55 (5)°; the dihedral angle between the two 4-chloro­phenyl rings is 12.16 (4)°. The crystal structure is stabilized by inter­molecular C—H⋯O inter­actions

1-Benzyl-3,5-bis­[(E)-3-thienyl­methyl­idene]piperidin-4-one

In the title mol­ecule, C22H19NOS2, the piperidine ring adopts an envelope conformation with the benzyl substituent in an equatorial position. Each of the olefinic double bonds has an E configuration. The dihedral angle between the two thio­phene rings is 1.55 (18)°. The thio­phene rings form angles of 72.21 (14) and 73.43 (14)° with the phenyl ring. Both thio­phene rings are disordered over two orientations [occupancy ratios of 0.799 (1):0.201 (1)] at 180° from one another. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds and C—H⋯π inter­actions help to stabilize the packing

Two-dimensional NMR spectral studies of some 2,6-diarylpiperidin-4-ones

662-66

Ethyl 6-r-(2-chlorophenyl)-2-oxo-4-phenyl­cyclohex-3-ene-1-t-carboxylate

In the title mol­ecule, C21H19ClO3, the cyclo­hexene ring adopts an envelope conformation, with all substituents equatorial. The plane through its five coplanar atoms makes dihedral angles of 12.75 (14) and 74.16 (8)° with the phenyl and benzene rings, respectively. The dihedral angle between the latter two rings is 81.73 (12)°. Inter­molecular C—H⋯O hydrogen bonds and intra­molecular C—H⋯Cl contacts are found in the crystal structure; a weak C—H⋯π inter­action is also present

2,3,5-Triphenyl­pyrazine

In the title mol­ecule, C22H16N2, the pyrazine ring deviates very slightly from planarity [maximum deviation 0.044 (3) Å], tending towards a twist-boat conformation. The phenyl ring at position 3 makes dihedral angles of 64.0 (2) and 45.8 (2)°, respectively, with the phenyl rings at positions 2 and 5. The dihedral angle between the phenyl rings at positions 2 and 5 is 49.7 (2)°. A C—H⋯π inter­action is found in the crystal structure, but no classical hydrogen bonds form

Ethyl 4-(4-bromo­phen­yl)-6-r-phenyl-2-oxocyclo­hex-3-ene-1-t-carboxyl­ate

In the title compound, C21H19BrO3, the cyclo­hexene ring adopts an envelope conformation, with all substituents equatorial. The plane through its five coplanar atoms makes dihedral angles of 28.88 (10) and 71.94 (10)° with the bromo­benzene and phenyl rings, respectively. The dihedral angle between the latter two rings is 51.49 (15)°. Inter­molecular C—H⋯O hydrogen bonds are found in the crystal structure; a C—H⋯π inter­action is also present

2-Methyl-3,5,6-triphenyl-2,3-dihydro­pyrazine

In the title mol­ecule, C23H20N2, the heterocyclic ring adopts a screw-boat conformation, with all substituents equatorial. The phenyl ring at position 3 makes dihedral angles of 78.12 (15) and 72.67 (15)°, respectively, with the phenyl rings at positions 5 and 6; the dihedral angle between the phenyl rings at positions 5 and 6 is 67.32 (14)°. A C—H⋯π inter­action is present in the crystal structure

5-Acetyl-4-(4-methoxy­phen­yl)-6-methyl-3,4-dihydro­pyrimidin-2(1H)-one

In the title mol­ecule, C14H16N2O3, the heterocyclic ring adopts a flattened boat conformation, and the plane through its four coplanar atoms makes a dihedral angle of 89.65 (7)° with the benzene ring. The non-H atoms of the carbonyl, acetyl and methyl groups are nearly coplanar with the attached heterocyclic ring. Inter­molecular N—H⋯O and C—H⋯O hydrogen bonds are present in the crystal structure