New pyrazole derivatives containing 1,2,4-triazoles and benzoxazoles as potent antimicrobial and analgesic agents.

Azole class of compounds are well known for their excellent therapeutic properties. Present paper describes about the synthesis of three series of new 1,2,4-triazole and benzoxazole derivatives containing substituted pyrazole moiety (11a-d, 12a-d and 13a-d). The newly synthesized compounds were characterized by spectral studies and also by C, H, N analyses. All the synthesized compounds were screened for their analgesic activity by the tail flick method. The antimicrobial activity of the new derivatives was also performed by Minimum Inhibitory Concentration (MIC) by the serial dilution method. The results revealed that the compound 11c having 2,5-dichlorothiophene substituent on pyrazole moiety and a triazole ring showed significant analgesic and antimicrobial activity.

Diethyl 4-[5-(4-chloro-phen-yl)-1H-pyrazol-4-yl]-2,6-dimethyl-1,4-dihydro-pyridine-3,5-dicarboxyl-ate.

In the title compound, C(22)H(24)ClN(3)O(4), intra-molecular C-H⋯O and C-H⋯N hydrogen bonds form S(9) and S(7) ring motifs, respectively. The 1,4-dihydro-pyridine ring adopts a flattened boat conformation. The benzene ring makes a dihedral angle of 33.36 (6)° with the pyrazole ring. In the crystal, pairs of N-H⋯N hydrogen bonds link the mol-ecules into inversion dimers. The dimers are stacked in column along the a axis through N-H⋯O and C-H⋯N hydrogen bonds. The crystal packing also features C-H⋯π inter-actions involving the pyrazole ring.

Dimethyl 2,6-dimethyl-4-{3-[4-(methyl-sulfan-yl)phen-yl]-1H-pyrazol-4-yl}-1,4-dihydro-pyridine-3,5-dicarboxyl-ate monohydrate.

In the title compound, C21H23N3O4S·H2O, the methyl-sulfanyl group is disordered over two sets of sites with site-occupancy factors of 0.631 (11) and 0.369 (11). The dihydro-pyridine ring adopts an E4 conformation. In the crystal, classical O-H⋯N, O-H⋯O and N-H⋯O hydrogen bonds, as well as C-H⋯O and C-H⋯S contacts, connect the mol-ecules into a three-dimensional network.

Ethyl 3-(2-eth-oxy-2-oxoeth-oxy)-6-(tri-fluoro-meth-yl)furo[3,2-c]quinoline-2-carboxyl-ate.

In the title compound, C19H16F3NO6, a quinoline derivative featuring an annealated furan substituent, the mean planes of the carb-oxy substituents are at an angle of 74.3 (2)°. In the crystal, C-H⋯O contacts result in undulating chains along [110]. C-H⋯F contacts also occur. The shortest centroid-centroid distance between rings is 3.3376 (7) Å, involving two furan rings of neighbouring mol-ecules.

1,5-Dibromo-2,4-dimeth-oxy-benzene.

In the title compound, C8H8Br2O2, all non-H atoms lie essentially in a common plane (r.m.s deviation of all fitted non-H atoms = 0.0330 Å). In the crystal, weak C-H⋯O hydrogen bonds connect the mol-ecules, forming chains which extend along the b-axis direction.

2-(4-Chloro-phen-yl)-2-oxoethyl 3,4-dimeth-oxy-benzoate.

In the title compound, C(17)H(15)ClO(5), the benzene rings forms a dihedral angle of 74.45 (10)°. In the crystal, mol-ecules are linked into C(13) chains along [011] via C-H⋯O hydrogen bonds. The crystal packing also features short Cl⋯Cl contacts of 3.1253 (10) Å.

2-(4-Chloro-anilino)-1-(4-chloro-phen-yl)ethanone.

In the title compound, C(14)H(11)Cl(2)NO, the benzene rings form a dihedral angle of 3.14 (6)°. Overall, the mol-ecule is close to being planar (r.m.s. deviation for all the non-H atoms = 0.054 Å). No significant directional inter-molecular inter-actions are observed in the crystal structure.

Hantzsch reaction: synthesis and characterization of some new 1,4-dihydropyridine derivatives as potent antimicrobial and antioxidant agents.

In the present study two new series of Hantzsch 1,4-dihydropyridine derivatives (1,4-DHPs) containing substituted pyrazole moiety (4a-f and 5a-f) were synthesized by the reaction of 3-aryl-1H-pyrazole-4-carbaldehydes with 1,3-dicarbonylcompounds (ethylacetoacetate and methylacetoacetate) and ammonium acetate. The newly synthesized compounds were characterized by IR, NMR, mass spectral study and also by C, H, N analyses. New compounds were screened for their antimicrobial activity by well plate method (zone of inhibition). Antioxidant studies of the synthesized compounds were also performed by measuring the DPPH radical scavenging assay. Compounds 4c, 4e and 4f were found to be potent antibacterial and antioxidant agents. The acute oral toxicity study for the compounds 4c, 4e and 4f were carried out and the experimental studies revealed that compounds 4c and 4e is safe up to 3000 mg/kg and no death of animals were recorded. However in compound 4f, we found mortality above 2000 mg and also significant behavioral changes in experimental animals.

Diethyl 4-[5-(biphenyl-4-yl)-1H-pyrazol-4-yl]-2,6-dimethyl-1,4-dihydro-pyridine-3,5-dicarboxyl-ate ethanol monosolvate.

In the title compound, C(28)H(29)N(3)O(4)·C(2)H(6)O, the benzene ring makes dihedral angles of 33.72 (13) and 32.86 (13)°, respectively, with the adjacent pyrazole and phenyl rings. In the crystal, the components are connected via inter-molecular N-H⋯O, N-H⋯N, O-H⋯O and C-H⋯O hydrogen bonds, forming a layer parallel to the bc plane.

Diethyl 4-[2-(4-meth-oxy-phen-yl)-1H-pyrazol-3-yl]-2,6-dimethyl-1,4-dihydro-pyridine-3,5-dicarboxyl-ate.

In the title compound, C(23)H(27)N(3)O(5), the pyrazole ring is inclined at dihedral angles of 38.16 (6) and 80.80 (6)°, respectively, to the least-squares planes of the benzene and dihydro-pyridine rings. In the crystal, adjacent mol-ecules are linked via a pair of N-H⋯N hydrogen bonds, forming an inversion dimer. The dimers are stacked in a column along the a axis through N-H⋯O hydrogen bonds. Intra- and inter-molecular C-H⋯N and C-H⋯O hydrogen bonds are also observed.

Synthesis, characterization and antimicrobial studies of some new pyrazole incorporated imidazole derivatives.

In the present study two series of novel imidazole derivatives containing substituted pyrazole moiety (3a-d and 5a-j) were synthesized. The first series were synthesized by the reaction of 3-aryl-1H-pyrazole-4-carbaldehyde thiosemicarbazones (2a-d) with DMAD and the second series by the reaction of 3-aryl-1H-pyrazole-4-carbaldehydes (1a-e) with 1,2-diketones (4a,b) in the presence of ammonium acetate. Structures of newly synthesized compounds were characterized by spectral studies. New compounds were screened for antifungal and antibacterial activities. Among the synthesized compounds, compound 3c was found to be potent antimicrobial agent. The acute oral toxicity study for the compound 3c was carried out and the experimental studies revealed that compound 3c is safe up to 3000 mg/kg and no death of animals were recorded.

Synthesis, characterization and anti-microbial studies of some novel 2,4-disubstituted thiazoles.

In the present study a series of novel 2,4-disubstituted thiazole derivatives containing substituted pyrazole moiety was synthesized by the reaction of 3-Aryl-1H-pyrazole-4-carbaldehyde thiosemicarbazone with 6-Bromo/H-3-(bromoacetyl)-2H-chromen-2-one/phenacyl chloride. Structures of newly synthesized compounds were characterized by spectral studies. New compounds were screened for their antibacterial studies against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The results revealed that compounds 7c, 8e, and 8f having 2,5-dichlorothiophene substituent and 8c, 8d having 2,4-dichlorophenyl substituent showed significant antibacterial activity against all tested microorganisms.

Novel chromeno [2,3-b]-pyrimidine derivatives as potential anti-microbial agents.

An efficient, microwave irradiated synthesis of novel chromeno[2,3-b]-pyrimidine derivatives was carried out. 2-amino-3,4-dihydro-2H-chromene-3-carbonitrile was converted into imine using N,N-Dimethylacetaldehyde dimethylacetal to give the core intermediate, which was used for the preparation of chromenopyrimidine library, using acetic acid and different amine in microwave irradiation for 5 min. Structures of newly synthesized compounds were confirmed by spectral studies. Compound 6g was characterized by single crystal X-ray analysis. All the compounds were also screened for their anti-microbial activity. Few of the compounds are found to be potential antimicrobials.

2-Dibutyl-amino-1-(2,7-dichloro-9H-fluoren-4-yl)ethanol.

In the title compound, C(23)H(29)Cl(2)NO, the fluorene ring is essentially planar, with a maximum deviation from the mean plane of 0.041 (1) Å. The amine group adopts a pyramidal configuration, the sum of the bond angles being 336.2 (3)°. In the crystal, the mol-ecules are linked into dimers by inter-molecular O-H⋯N and C-H⋯O hydrogen bonds. Weak C-H⋯π and π-π [centroid-centroid distance = 3.7544 (7) Å] inter-actions are also observed.

(1Z)-1-(2,4-Dichloro-phen-yl)ethan-1-one semicarbazone.

In the title compound, C(9)H(9)Cl(2)N(3)O, the semicarbazone group is approximately planar, with an r.m.s deviation from the mean plane of 0.011 (2) Å. The dihedral angle between the least-squares planes through the semicarbazone group and the benzene ring is 38.76 (9)°. The crystal structure is further stabilized by N-H⋯O and C-H⋯O hydrogen bonding.

4-Amino-3-(1-naphthyl-oxymeth-yl)-1H-1,2,4-triazole-5(4H)-thione.

In the title compound, C(13)H(12)N(4)OS, the dihedral angle between the triazole and naphthalene ring systems is 67.42 (5)°. In the crystal, adjacent mol-ecules are linked via two pairs of inter-molecular N-H⋯S inter-actions, forming R(2) (2)(8) and R(2) (2)(10) ring motifs. Weak C-H⋯S inter-actions generate infinite chains along [001] and the structure is further consolidated by C-H⋯π bonds and aromatic π⋯π stacking inter-actions [distance between the centroids of the triazole rings = 3.2479 (7) Å].

5-Diethyl-amino-2-[(E)-(4-methyl-3-nitro-phenyl)-imino-meth-yl]phenol: a redetermination.

The title compound, C(18)H(21)N(3)O(3), is a potential bidentate Schiff base ligand. The whole mol-ecule is disordered with a refined site-occupancy ratio of 0.567 (4):0.433 (4) and not just one ethyl group as reported previously [Sarojini et al. (2007 ▶). Acta Cryst. E63, o4782-o4782]. Using the whole mol-ecule disorder, R values are much smaller than those published. An intra-molecular O-H⋯N hydrogen bond generates a six-membered ring, producing an S(6) ring motif. The dihedral angle between the mean plane of the two benzene rings (major component) is 9.0 (5)°. The crystal structure shows short C⋯C [3.189 (15)-3.298 (12) Å] and C⋯O [2.983 (5)-3.149 (13) Å] contacts. Inter-molecular C-H⋯O inter-actions link neighbouring mol-ecules into dimers with R(2) (2)(18) motifs. In the crystal structure, these dimers are linked together by inter-molecular C-H⋯O inter-actions into one-dimensional extended chains along the b axis. The crystal structure is further stabilized by inter-molecular π-π stacking inter-actions [centroid-centroid distances = 3.458 (8)-3.691 (6) Å].

(Z)-1-(2,5-Dichloro-3-thien-yl)ethanone semicarbazone.

The title mol-ecule, C(7)H(7)Cl(2)N(3)OS, is approximately planar [maximum deviation = 0.062 (1) Å]. Short inter-molecular distances between the centroids of the five-membered rings [3.5340 (8) Å] indicate the existence of π-π inter-actions. An inter-esting feature of the crystal structure is the presence of short intra-molecular Cl⋯N inter-actions [3.0015 (11) Å]. Mol-ecules are linked via pairs of inter-molecular N-H⋯O hydrogen bonds, generating R(2) (2)(8) ring motifs. Furthermore, N-H⋯O hydrogen bonds form R(2) (1)(7) ring motifs with C-H⋯O contacts, further consolidating the crystal structure. In the crystal, mol-ecules are linked by these inter-molecular inter-actions, forming chains along [001].

4-Amino-3-(o-tolyl-oxymeth-yl)-1H-1,2,4-triazole-5(4H)-thione.

The asymmetric unit of the title compound, C(10)H(12)N(4)OS, contains two independent mol-ecules, A and B, which differ significantly in the relative orientations of the benzene and triazole rings. The dihedral angle between the above two rings is 6.94 (5)° in mol-ecule A and 77.60 (5)° in mol-ecule B. In the crystal, mol-ecules are linked into a three-dimensional network by N-H⋯S, N-H⋯O, N-H⋯N and C-H⋯S hydrogen bonds and π-π inter-actions between the benzene and triazole rings [centroid-centroid distance = 3.5311 (6) Å] are also present.

4-Amino-3-(p-tolyl-oxymeth-yl)-1H-1,2,4-triazole-5(4H)-thione.

In the title triazole compound, C(10)H(12)N(4)OS, the triazole ring is essentially planar [maximum deviation = 0.009 (1) Å] and forms a dihedral angle of 5.78 (4)° with the benzene ring. In the crystal structure, mol-ecules are linked into dimers by centrosymmetric N-H⋯S inter-actions. These dimers are linked into two-mol-ecule-wide tapes by N-H⋯N and S⋯S [3.2634 (3) Å] inter-actions. In addition, they are further inter-connected by weak N-H⋯S inter-actions into sheets parallel to the ab plane. The crystal structure is further stabilized by weak inter-molecular C-H⋯π inter-actions.