6-Methyl-4-{[4-(tri-methyl-sil-yl)-1H-1,2,3-triazol-1-yl]meth-yl}-2H-chromen-2-one.

In the title compound, C16H19N3O2Si, the dihedral angle between the coumarin ring system (r.m.s. deviation = 0.031 Å) and the triazole ring is 73.81 (8)°. In the crystal, mol-ecules are linked into [010] chains by weak C-H⋯O inter-actions.

Crystal structure of ethyl 5-acetyl-2-{[(di-methyl-amino)-methyl-idene]amino}-4-methyl-thio-phene-3-carboxyl-ate.

In the title thio-phene derivative, C13H18N2O3S, the dihedral angles between the thio-phene ring and the [(di-methyl-amino)-methyl-idene]amino side chain (r.m.s. deviation = 0.009 Å) and the -CO2 ester group are 3.01 (16) and 59.9 (3)°, respectively. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds generate R 2 (2)(16) loops. The dimers are linked by another weak C-H⋯O inter-action, forming chains along [001]. In addition, weak C-H⋯π inter-actions are observed, which link the chains into (001) layers.

Crystal structure of 2-acetyl-5-(3,4-di-meth-oxy-phen-yl)-6-eth-oxy-carbonyl-3,7-dimethyl-5H-thia-zolo[3,2-a]pyrimidin-8-ium chloride.

The title mol-ecular salt, C21H25N2O5S(+)·Cl(-), crystallizes with two ion pairs in the asymmetric unit. The cations have similar conformations (r.m.s. overlay fit = 0.40 Å), with one of them showing disorder of the terminal methyl group of the ester in a 0.72 (2):0.28 (2) ratio. In the first cation, the 3,4-dimeth-oxy-substituted phenyl ring subtends a dihedral angle of 88.38 (7)° with the pyrimidine ring and 6.79 (8)° with the thia-zole ring. The equivalent data for the second cation are 89.97 (3) and 6.42 (7)°, respectively. The pyrimidine ring adopts a sofa conformation in each cation. In the crystal, the components are linked by N-H⋯Cl hydrogen bonds, generating isolated ion pairs. The ion pairs are are linked by C-H⋯O inter-actions, generating a three-dimensional network. In addition, a weak C-H⋯π inter-action is observed.

Crystal structure of ethyl 2-acetyl-3,7-dimethyl-5-(thio-phen-2-yl)-5H-thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate.

In the title compound, C17H18N2O3S2, the pyrimidine ring adopts a shallow sofa conformation, with the C atom bearing the axially-oriented thio-phene ring as the flap [deviation = 0.439 (3) Å]. The plane of the thio-phene ring lies almost normal to the pyrimidine ring, making a dihedral angle of 79.36 (19)°. In the crystal, pairs of very weak C-H⋯O hydrogen bonds link the mol-ecules related by twofold rotation axes, forming R 2 (2)(18) rings, which are in turn linked by another C-H⋯O inter-action, forming chains of rings along [010]. In addition, weak C-H⋯π(thio-phene) inter-actions link the chains into layers parallel to [001] and π-π inter-actions with a centroid-centroid distance of 3.772 (10) Šconnect these layers into a three-dimensional network.

Crystal structure of ethyl 5-[3-(di-methyl-amino)-acrylo-yl]-2-{[(di-methyl-amino)-methyl-idene]-amino}-4-methylthio-phene-3-carb-oxy-late.

In the title compound, C16H23N3O3S, the dihedral angles between the thio-phene ring and the almost planar di-methyl-amino-methyl-ene-amino (r.m.s. deviation = 0.005 Å) and di-methyl-amino-acryloyl (r.m.s. deviation = 0.033 Å) substituents are 6.99 (8) and 6.69 (7)°, respectively. The ester CO2 group subtends a dihedral angle of 44.92 (18)° with the thio-phene ring. An intra-molecular C-H⋯O hydrogen bond generates an S(6) ring. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds generate R (2) 2(14) loops. In addition, a weak C-H⋯π inter-action is observed.

Crystal structure of 2-acetyl-5-(3-methoxyphenyl)-3,7-dimethyl-5H-1,3-thiazolo[3,2-a]pyrimidine-6-carboxylate.

In the title mol-ecule, C20H22N2O4S, the pyrimidine ring is in a flattened half-chair conformation and the 3-meth-oxyphenyl substituent is in an axial arrangement. The thia-zole ring forms a dihedral angle of 81.3 (1)° with the benzene ring. In the crystal, weak C-H⋯S inter-actions link mol-ecules into chains along [001]. In addition, there are π-π inter-actions between inversion-related thia-zole rings with a centroid-centroid distance of 3.529 (2) Å. The ethyl group was refined as disordered over two sets of sites with an occupancy ratio of 0.52 (3):0.48 (2).

Crystal structure of 1-(2,4-di-methyl-phen-yl)-2-(4-tri-methyl-silyl-1H-1,2,3-triazol-1-yl)ethanone.

The asymmetric unit of the title compound, C15H21N3OSi, contains two mol-ecules with similar conformations (r.m.s. overlay fit for the 20 non-H atoms = 0.163 Å). The dihedral angles between the planes of the 1,2,3-triazole and 2,4-di-methyl-benzene rings are 27.0 (3) and 19.5 (3)°. In the crystal, mol-ecules are linked by very weak C-H⋯O and C-H⋯N hydrogen bonds to generate [100] chains. The chains are cross-linked by C-H⋯π inter-actions.