K. E. ManojKumar

Synthesis, antibacterial, anthelmintic and anti-inflammatory studies of novel methylpyrimidine sulfonyl piperazine derivatives

A strategic synthesis of novel methylpyrimidine sulfonyl piperazines involving Suzuki coupling was designed and pharmacological activities of the compounds were evaluated. Reactions were carried out under conventional method and show good functional group transformations and high yields. Structures of the newly synthesized compounds were established by infrared spectroscopy (IR), 1H and 13C nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) and elemental analysis. The compounds were tested for in vitro antibacterial activity against Escherichia coli and Staphylococcus aureus bacterial strains, anthelmintic activity using Pheretima posthuma and anti-inflammatory activity involving carrageenan induced rat paw edema model. Some compounds were proven to be potent pharmacophores.

1-Tosyl-4-[2-(trifluoro-meth-yl)benz-yl]piperazine.

In the crystal structure of the title compound, C19H21F3N2O2S, the piperazine ring adopts a chair conformation. The dihedral angles between the mean plane of the piperazine ring and the tosyl and trifluoromethylphenyl rings are 74.52 (3) and 68.30 (2)°, respectively. The sulfonamide N atom deviates from the plane defined by the three attached atoms by 0.327 (1) Å. The crystal structure is stabilized by weak C—H⋯π interactions.

2-[5-(2-Fluoro­phen­yl)-3-isobutyl-1H-pyrazol-1-yl]benzoic acid

In the title compound, C20H19FN2O2, the dihedral angle between the aromatic rings is 62.1 (1)°, and those between the pyrazole ring and the fluorobenzene and benzoic acid rings are 52.1 (1) and 53.1 (1)°, respectively. In the crystal, molecules are linked into [010] C(7) chains by O—H⋯N hydrogen bonds.

tert-Butyl 4-{5-[3-(tri­fluoro­meth­oxy)phen­yl]-1,2,4-oxa­diazol-3-yl}piperazine-1-carboxyl­ate

In the title compound, C18H21F3N4O4, the piperazine ring adopts a chair conformation and the dihedral angle between the oxadiazole and benzene rings is 6.45 (14)°. The C atoms and their attached H atoms in the piperazine ring are disordered, with site-occupation factors of 0.576 (12) and 0.424 (12). In the crystal, molecules are linked through weak C—H⋯O interactions, generating an R 2 2(12) motif. Further, secondary C—H⋯O intermolecular interactions link the molecules into C(6) chains along [100].

An unknown solvate of 1-(2,4-di­chloro­benz­yl)-4-[(4-methyl­phen­yl)sulfon­yl]piperazine

In the title compound, C18H20Cl2N2O2S, the piperazine ring adopts a chair conformation. The dihedral angle between the sulfonyl-bound benzene ring and the best-fit plane through the six non-H atoms of the piperazine ring is 72.22 (12)°; those between the dichlorobenzene ring and the sulfonyl and piperazine rings are 2.44 (13) and 74.16 (2)°, respectively. In the crystal, molecules are connected through weak C—H⋯O interactions into a hexameric unit generating a R 6 6(60) motif in the ab plane. The molecules are also connected into C(4) chains through weak C—H⋯N interactions. The solvent used to grow the crystal was a mixture of dichloromethane and methanol, but the resulting electron density was uninterpretable. The solvent contribution to the scattering was removed with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]. The formula mass and unit-cell characteristics do not take into account the disordered solvent.

(E)-3-Chloro-N′-hy­droxy­benzene-1-carboximidamide

The title compound, C7H7ClN2O, crystallizes with two independent molecules in the asymmetric unit. The compound adopts an E configuration across the C=N double bond, as the –OH group and the benzene ring are on opposite sides of the double bond while the H atom of the hydroxy group is directed away from the –NH2 group. In the crystal, molecules are linked to one another through O—H⋯N and N—H⋯O hydrogen bonds, forming chains along [010].

6-[4-Chloro-2-(trifluoro­meth­yl)phen­yl]-3-fluoro-2-methyl­pyridine

In the title compound, C13H8ClF4N, the dihedral angle between the benzene and pyridine rings is 59.8 (3)°. In the crystal, molecules are stacked in columns along the b axis through weak C—H⋯π interactions.

(E)-tert-Butyl 4-(N'-hy-droxy-carbam--imid-o-yl)piperazine-1-carboxyl-ate.

In the title compound, C10H20N4O3, the piperazine ring adopts a chair conformation. The molecule adopts an E conformation across the C=N double bond, with the –OH group and the piperazine ring trans to one another. Further, the H atom of the hydroxy group is directed away from the NH2 group. An intramolecular N—H⋯O contact occurs involving the NH2 group and the oxime O atom. In the crystal, molecules are linked via strong N—H⋯O and O—H⋯N hydrogen bonds with alternating R 2 2(6) and C(9) motifs into tetrameric units forming R 4 4(28) motifs.

1-Fluoro-4-[(E)-2-nitro­vin­yl]benzene

The title compound, C8H6FNO2, is almost planar (r.m.s. deviation for the non-H atoms = 0.019 Å) and the conformation across the C=C bond is trans. The C and H atoms of the side chain are disordered over two sets of sites in a 0.56 (3):0.44 (3) ratio. In the crystal, molecules are linked by C—H⋯O interactions, thus forming C(5) chains propagating in [001].

tert-Butyl 2-{[5-(4-cyano-phen-yl)pyridin-3-yl]sulfon-yl}acetate.

In the title compound, C18H18N2O4S, the dihedral angle between the aromatic rings is 33.71 (9)° and an intramolecular C—H⋯O hydrogen bond closes an S(6) ring. In the crystal, molecules are linked by C—H⋯O and C—H⋯N hydrogen bonds to generate a three-dimensional network. A very weak aromatic π–π stacking interction is also observed [centroid–centroid separation = 3.9524 (10) Å].