Nikhath Fathima

2-[4-(Trifluoro­meth­oxy)phen­yl]-1H-benzimidazole

In the title compound, C14H9F3N2O, the best planes of the benzimidazole group and benzene ring form a dihedral angle of 26.68 (3)°. In the crystal, N—H⋯N hydrogen bonds link the molecules into infinite chains parallel to the c axis. Stacking interactions between the benzimidazole groups [centroid–centroid distance = 3.594 (5) Å] assemble the molecules into layers parallel to (100). The trifluoromethyl group is disordered over three sets of sites with site-occupancy factors of 0.787 (4), 0.107 (7) and 0.106 (7).

2-(3,4-Di­fluoro­phen­yl)-1H-benzimidazole

In the title molecule, C13H8F2N2, the dihedral angle between the benzimidazole ring system and the difluoro-substituted benzene ring is 30.0 (1)°. In the crystal, molecules are linked by N—H⋯N hydrogen bonds, forming chains along [010]. In addition, weak C—H⋯F hydrogen bonds connect chains into a two-dimensional network parallel to (001). A weak C—H⋯π interaction is observed between an H atom of the benzimidazole ring sytem and the π system of the difluoro-substituted benzene ring.

Methyl 5-(4-acet­oxy­phen­yl)-2-(2-bromo­benzyl­idine)-7-methyl-3-oxo-2,3-di­hydro-5H-1,3-thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate

In the title molecule, C24H19BrN2O5S, the pyrimidine ring is in a flattened half-chair conformation and the 4-acetoxyphenyl group is substituted axially to this ring. The thiazole ring is essentially planar [with a maximum deviation of 0.012 (2) Å for the N atom] and forms dihedral angles of 17.65 (13) and 88.95 (11)° with the bromo- and acetoxy-substituted benzene rings, respectively. The dihedral angle between the benzene rings is 81.84 (13) Å. In the crystal, pairs of weak C—H⋯O hydrogen bonds lead to the formation of inversion dimers. A weak C—H⋯π interaction and π–π stacking interactions with centroid–centroid distances of 3.5903 (14) Å are observed.

Methyl 2-(2-bromo-benzyl-idene)-5-(4-hy-droxy-phen-yl)-7-methyl-3-oxo-2,3-dihydro-5H-1,3-thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate.

In the title compound, C22H17BrN2O4S, the central dihydropyrimidine ring, with a chiral C atom, is significantly puckered and adopts a half-chair conformation with the chiral C atom displaced from the mean plane of the remaining ring atoms by 0.305 (6) Å. The hydroxy-phenyl ring is positioned axially to the pyrimidine ring and almost bisects it, the dihedral angle between the mean-planes of the two rings being 89.78 (12)°. The methoxycarbonyl group is disordered over two sites with an occupancy ratio of 0.568 (5):0.432 (5), resulting in a major and a minor conformer. In the crystal, O—H⋯N and C—H⋯S interactions result in sheets along the c axis. The supramolecular assembly is stabilized by π–π stacking interactions between the 2-bromobenzylidene and thiazolopyrimidine rings [centroid–centroid distance = 3.632 (1) Å]. In addition, C—H⋯π interactions are also observed in the crystal structure.

2-Phenyl-8,9,10,11-tetra­hydro-1-benzo­thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine

In the title compound, C17H14N4S, the benzothieno moiety is fused at one end of the pyramidine ring while the triazole ring with a phenyl substituent is fused at the other side. The triazole ring is almost planar [maximum deviation = 0.0028 (3) Å] while the cyclohexane ring adopts a half-chair conformation. In the crystal, pairs of intermolecular C—H⋯N hydrogen bonds form centrosymmetric head-to-head dimers, corresponding to an R 2 2(8) graph-set motif. Further C—H⋯N interactions generate a zigzag chain of molecules along the c axis. The supramolecular assembly is consolidated by π–π stacking interactions [centroid–centroid distance = 3.445 (4) Å].

Synthesis and crystal structure analysis of two thiazolo[3,2-a]pyrimidine derivatives

Synthesis of 5R*-(3-methoxy-phenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-2,6-dicarboxylic acid diethyl ester (2a) and 3,7-dimethyl-5S*-thiophen-2-yl-5H-thiazolo[3,2-a]pyrimidine-2,6-dicarboxylic acid diethyl ester (2b) are achieved by the cyclocondensation of 3,4-dihydropyrimidine-2-thione derivative with α-haloester. Preliminary analysis was done spectroscopically by means of 1H NMR spectra, mass spectra and elemental analyses. Further the structures were confirmed by X-ray crystal structure analysis. The two molecules are not identical in configuration. In both the compounds the central pyrimidine ring adopts a conformation which is best described as an intermediate between a boat and screw boat form. The crystal structure is stabilized by intermolecular C-H…O and C-H…π weak interactions.

Methyl 4-(4-hy­droxy­phen­yl)-6-methyl-2-sulfanyl­idene-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

In the title molecule, C13H14N2O3S, the dihydropyrimidine ring is in a flattened sofa conformation, with the methine C atom forming the flap. The dihedral angle between the mean plane of the five essentially planar atoms of the dihydropyrimidine ring [maximum deviation = 0.056 (4) Å] and the benzene ring is 89.4 (2)°. The O atom of the carbonyl group is in a trans conformation with respect to the C=C bond of the dihydropyrimidine ring. In the crystal, N—H⋯O and O—H⋯S hydrogen bonds connect molecules, forming a two-dimensional network parallel to (001).

6-Chloro-3-[(di­methyl­amino)­methyl­idene]thio­chroman-4-one

The asymmetric unit of the title compound, C12H12ClNOS, contains three independent molecules, with the thiochroman ring adopting a sofa conformation in each one. The crystal structure features C—H⋯O interactions; one of the O atoms accepts three such bonds. Together, the hydrogen bonds give rise to a molecular tape propagating in [010].

1-(2-Chloro-eth-yl)-1H-pyrazolo-[3,4-d]pyrimidin-4(5H)-one.

In the title compound, C7H7ClN4O, the pyrazolopyrimidine ring is essentially planar, the r.m.s. deviation of the fitted atoms being 0.0071 Å. The crystal structure features strong N—H⋯O hydrogen bonds and further consolidated by weak C—H⋯O, C—H⋯N and C—H⋯Cl interactions.

Ethyl 3-acetyl-4-(3-meth­oxy­phen­yl)-6-methyl-2-sulfanyl­idene-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

In the title compound, C17H20N2O4S, the aryl ring is positioned perpendicular to the dihydropyrimidine ring, the dihedral angle between the ring planes being 77.48 (9)°. The carboxylate and methyl groups are in a cis conformation with respect to the C=C bond. The dihydropyrimidine ring adopts a twist-boat conformation. The crystal structure is stabilized by N—H⋯O and C—H⋯O interactions, the former resulting in molecular chains along the b axis and the latter forming inversion dimers.