Crystal Structure of Ethyl 2-Cyano-3-[(1-ethoxyethylidene) Amino]-5-(3-methoxyphenyl)-7-Methyl-5H-1,3-Thiazolo[3,2-A]pyrimidine-6-Carboxylate

In the title compound, C22H24N4O4S, the central pyrimidine ring adopts a sofa conformation with the ring-junction N atom displaced by 0.2358 (6) Å from the mean plane of the remaining ring atoms. The 3-methoxyphenyl ring, at the chiral C atom opposite the other N atom, is positioned axially and is inclined to the thiazolopyrimidine ring with a dihedral angle of 83.88 (7)°. The thiazole ring is essentially planar (r.m.s. deviation = 0.0034 Å). In the crystal, pairs of weak C—H...O hydrogen bonds link molecules related by twofold rotation axes to form R22(8) rings, which in turn are linked by weak C—H...N interactions, forming ribbons along [-110]. In addition, π-π stacking interactions [centroid—centroid distance = 3.5744 (15) Å] connect the ribbons, forming slabs lying parallel to (001)

Diethyl 2,6-Dimethyl-4-(naphthalen-1-yl)-1,4-Dihydropyridine-3,5-Dicarboxylate

In the title compound, C23H25NO4, the 1,4-dihydropyridine ring adopts a flattened boat conformation. The naphthalene ring system forms a dihedral angle of 88.59 (6)° with the pyridine ring. In the crystal, N—H...O and C—H...O hydrogen bonds generate an R12(6) ring motif and result in a zigzag chain along the b axis. Additional C—H...O hydrogen bonds form infinite chains along the c-axis direction

Synthesis and x-ray crystal structure of a CuII-theophylline complex: [Cu(theo)2 (H2O)3]·2H2O

The complex [Cu-II (theo)(2)(H2O)(3)].2H(2)O (theo = theophylline) was obtained from aqueous solution. The crystals belong to the monoclinic system, space group P2(1)/n, and are reflection twins about the (001) face. The structure was solved using data from a twinned crystal and refined to final R and R(W) values of 0.069 and 0.064, respectively. Copper has a square-pyramidal coordination with two thee molecules coordinating through N(7) at equatorial positions. The remaining sites are occupied by water molecules. O(6) of one of the thee molecules is at the other axial site at a longer distance of 3.18 Angstrom. This could lead to an alternate (4+1+1) octahedral coordination geometry for Cu-II. The packing is stabilized by stacking interactions between the theophylline moieties at an average separation of 3.46 Angstrom

Structural Modifications Leading to Changes in Supramolecular Aggregation of Thiazolo[3, 2-A]Pyrimidines: Insights into their Conformational Features

The compounds, 7-methyl-3,5-diphenyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid ethyl ester (1), 3-amino-2-cyano-7-methyl-5-phenyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid methyl ester (2), 2-dimethylaminomethylene-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine- 6-carboxylic acid ethyl ester (3), 2-(3-cyano-benzylidene)-5-(4-hydroxy-phenyl)-7-methyl-3-oxo-2,3- dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid methyl ester; with N,N-dimethyl-formamide (4) and 3-ethoxycarbonylmethyl-5-(4-hydroxy-3-methoxy-phenyl)-7-methyl-5H-thiazolo[3,2-a]pyrimidine-6- carboxylic acid methyl ester (5) have been synthesized and their structures evaluated crystallographically. Compound 1 crystallizes in the space group P¯i with Z=8, with four molecules in the asymmetric unit. Compound 2 also crystallizes in the space group P¯i with Z=4 wherein asymmetric unit accommodates two molecules. Compound 3 belongs to P21/c with Z=4, compound 4 crystallizes in Pbc21 with Z= 4 and compound 5 belongs to P¯i with Z=2. In all the above compounds, the aryl ring positioned at C5 of thiazolopyrimidine ring is almost perpendicular. In the case of compounds with substituted phenyl ring, aryl group-up conformation predominates. However, for compounds with unsubstituted phenyl ring, aryl group-down conformation is adopted. By varying the substituents at positions C2, C3, C6 and on the aryl at C5 in the main molecular scaffold of (1-5), we have observed significant differences in the intermolecular interaction patterns. The packing features of the compounds are controlled by C-H…O, C-H…N, N-H…N O-H…N, C-H…p and p…p weak interactions

Crystal Structure of Ethyl 2-(2-fluorobenzylidene)-5-(4-fluorophenyl)-7-Methyl-3-Oxo-2,3-Dihydro-5H-1,3-Thiazolo[3,2-A]pyrimidine-6-Carboxylate

In the title molecule, C23H18F2N2O3S, the 4-fluoro-substituted and 2-fluoro-substituted benzene rings form dihedral angles of 88.16 (8) and 23.1 (1)°, respectively, with the thiazole ring. The pyrimidine ring adopts a flattened sofa conformation with the sp3-hydridized C atom forming the flap. In the crystal, pairs of weak C—H...O hydrogen bonds link molecules related by twofold rotation axes, forming R22(10) rings, which are in turn linked by weak C—H...N interactions to form chains of rings along [010]. In addition, weak C—H...π(arene) interactions link the chains into layers parallel to (001) and π-π interactions with a centroid-centroid distance of 3.836 (10) Å connect these layers into a three-dimensional network

Methyl 5-(4-hy­droxy-3-meth­oxy­phen­yl)-2-(4-meth­oxy­benzyl­idene)-7-methyl-3-oxo-2,3-dihydro-5H-thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate

In the title compound, C24H22N2O6S, a pyrimidine ring substituted with 4-hy­droxy-3-meth­oxy­phenyl is fused with a thia­zole ring. The 4-hy­droxy-3-meth­oxy­phenyl group is positioned axially to the pyrimidine ring, making a dihedral angle 85.36 (7)°. The pyrimidine ring adopts a twist boat conformation. In the crystal, O—H⋯N inter­actions result in a chain running along the b axis. The carbonyl O atom bonded to the thia­zole ring is involved in two C—H⋯O hydrogen-bond inter­actions forming centrosymmetric dimers; the ten- and six-membered rings resulting from these inter­actions have R 2 2(10) and R 1 2(6) motifs, respectively

Synthesis and Crystal Structure Analysis of Ethyl-4-(4-Acetoxy-Phenyl)-3-Acetyl-6-Methyl-2-Thioxo-1,2,3,4-Tetrahydro-Pyrimidine-5-Carboxylate

4-(4-Acetoxy-phenyl)-3-acetyl-6-methyl-2-thioxo-1,2,3,4-tetrahydro-pyrimidine-5-carboxylic acid ethyl ester (2) was synthesized by a two step reaction process. Preliminary spectroscopic analysis was done by IR, 1HNMR and elemental analysis. The crystal and molecular structure was further confirmed using single crystal x-ray diffraction. The dihedral angle between the planes of the aryl and dihydropyrimidine rings is 89.65(6)°, which is almost orthogonal. The dihydropyrimidine ring adopts twist-boat conformation. The crystal structure is stabilized by C-H…O, N-H…S and C-H…π interactions

Synthesis and crystal structure of ethyl 2-​{5-​[2-​(2,​6-​dichlorophenylamino)​benzyl]​-​4-​p-​tolyl-​4H-​1,​2,​4-​triazol-​3-​ylthio}​acetate

The compound 2-{5-[2-(2,6-dichlorophenylamino)benzyl]-4-p-tolyl-4H-1,2,4-triazol-3-ylthio}acetate has been prepared and characterized by IR, 1H NMR, 13C NMR and mass spectra. The crystal and molecular structure were further confirmed using single crystal X-ray diffraction. The crystal structure has been found to be stabilized by intermolecular C–H···O interaction generating bifurcated hydrogen bonds whereas the C–H···N interactions generate chain of molecules. The intramolecular N–H···N hydrogen bond forms a ring with S(7) graph-set motif

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