A series of novel pyrazolyl isoxazolines were synthesized by 1,3-dipolar cycloaddition of pyrazolyl nitrile oxide with various activated alkene, such as acrylonitrile, methyl acrylate, and vinyl acetate, in the presence of iodobenzene diacetate in methanol containing a catalytic amount of TFA at room temperature (13 compounds upto 92% yield were isolated).

The synthesis of a series of 21 novel 3-alkyl/aryl-7/9-methyl-10,10a-dihydroindeno[1,2-e][1,2,4]triazolo[3,4-b][1,3,4]thiadiazines (4) has been achieved by the cyclocondensation between 4/6-methyl-2-tosyloxy-1-indanones (2) and 3-alkyl/aryl-4-amino-5-mercapto-1,2,4-s-triazoles (3). 4/6-Methyl-2-tosyloxy-1-indanones (2) were readily accessible through hypervalent iodine oxidation of 4/6-methyl-1-indanones using [(hydroxy)tosyloxyiodo]benzene (HTIB, Koser's reagent) in acetonitrile.

A series of new symmetrical 3,6-bis(aryl)bis([1,2,4]triazolo)[3,4-a:4′,3′-c]phthalazines 9a-l has been conveniently synthesized by oxidative cyclization of 1,4-bis(substituted benzalhydrazino)phthalazines 8a-l promoted by iodobenzene diacetate under mild conditions (12 examples, up to 93% yield). All the 12 compounds were tested in vitro for their antibacterial activity against two Gram-positive bacteria, namely, Staphylococcus aureus, Bacillus subtilis and two Gram-negative bacteria, namely, Escherichia coli and Pseudomonas aeruginosa. All the synthesized compounds were also tested for their antifungal action against two fungi, Aspergillus niger and Aspergillus flavus.

Synthesis of a series of new 4-substituted-3-aryl-1-(2,6-dimethylpyrimidin-4-yl)pyrazoles (2a, 2b, 2c, 2d, 2e, 2f, 2g, 3a, 3b, 3c, 3d, 3e, 3f, 3g, and 4a, 4b, 4c, 4d, 4e, 4f, 4g) is described. All the synthesized compounds were evaluated in vitro for their antibacterial activity against two gram-positive and two gram-negative bacteria, namely, Bacillus subtilis (MTCC 8509), Bacillus stearothermophilus (MTCC 8508), Escherichia coli (MTCC 51), and Pseudomonas putida (MTCC 121), and their activity was compared with two commercial antibiotics, streptomycin and chloramphenicol. Two compounds, namely, 3-(4-anisyl)-1-(2,6-dimethylpyrimidin-4-yl)pyrazole-4-carboxaldehyde (2b) and 3-(2-thienyl)-1-(2,6-dimethyl pyrimidin-4-yl)pyrazole-4-carboxaldehyde (2g) were found to be equipotent to streptomycin and chloramphenicol against gram-negative bacteria, E. coli having minimum inhibitory concentration (MIC) value = 4 μg/mL. Compounds 4b and 4d also displayed good activity against E. coli with MIC = 8 μg/mL. J. Heterocyclic Chem., (2011).