Search

A variety of 3,4-disubstituted pyrroles and pyrazoles were synthesized by the treatment of 1,3-dipolar reagents viz., tosylmethyl isocyanide, and diazomethane to heteroaryl chalcones and evaluated for their antimicrobial activity. Among all the tested compounds, 14b and 15b displayed promising antimicrobial activity when compared with the standards particularly against Bacillus subtilis and Aspergillus niger.

A new class of pyridinylcarbamoylmethyl pyrrolyl/pyrazolylcarboxamides was prepared from the synthetic intermediate pyridinylcarbamoylmethyl cinnamamide adopting simple and versatile synthetic methodologies. All the synthesized compounds were evaluated for antioxidant activity. Among all the tested compounds, the methoxy-substituted pyrazolyl pyridines displayed significant antioxidant activity in all the three methods when compared with the standard ascorbic acid. Moreover, compounds having more number of electron-donating groups exhibited greater activity.

A new class of benzazolyl pyrazoles were prepared from the simple substrates benzoxazol-2-thiol, benzothiazol-2-thiol, 1H-benzimidazol-2-thiol and cinnamoyl chloride and tested for antimicrobial activity. The compounds 2-(benzothiazol-2-ylthio)-1-(3-(benzothiazol-2-ylthio)-5-phenyl-1H-pyrazol-1-yl)ethanone and 2-(benzothiazol-2-ylamino)-1-(3-(benzothiazol-2-ylthio)-5-phenyl-1H-pyrazol-1-yl)ethanone showed pronounced antibacterial activity against Klebsiella pneumoniae whereas 2-(1H-benzimidazol-2-ylthio)-1-(3-(1H-benzimidazol-2-ylthio)-5-phenyl-1H-pyrazol-1-yl)ethanone and 2-(1H-benzimidazol-2-ylamino)-1-(3-(1H-benzimidazol-2-ylthio)-5-phenyl-1H-pyrazol-1-yl) ethanone displayed excellent antifungal activity against Penicillium chrysogenum.

The bis and tris heterocycles-benzoxazolyl/benzothiazolyl/benzimidazolyl quinazolines linked by sulfur and/or nitrogen were prepared from 2,4-dichloroquinazoline and benzazolyl-2-thiol/benzazolyl-2-amine and studied their antibacterial activity. The nitro-substituted sulfur-linked bisbenzothiazolylquinazoline (12f), bisbenzimidazolylquinazoline (13f), and nitro-substituted sulfur and nitrogen-linked bisbenzothiazolylquinazoline (15f) were found to be potential antibacterial agents against Staphylococcus aureus.

The bis(oxazolyl and/or thiazolyl)hydrazines were prepared, and their anti-allergic activity was studied. All the compounds displayed variable extent of anti-allergic activity on immunoglobulin E/silver-stimulated RBL-2H3 cells at 50 and 100 μM concentrations. The unsubstituted and chlorosubstituted compounds showed higher activity than those having methyl substituent. Compounds 9c and 10c do not cause cytotoxicity of the cells at 50 and 100 μM and also significantly inhibit β-hexosaminidase release stimulated by immunoglobulin E/silver at 50 and 100 μM.

A new class of azolyl pyrimidines linked by diamino sulfone moiety was prepared and studied their antimicrobial activity. Chloro-substituted and nitro-substituted thiazolyl pyrimidines (9c and 9e) showed excellent antibacterial activity against Bacillus subtilis, while imidazolyl pyrimidines (10c and 10e) exhibited promising antifungal activity against Aspergillus niger.

A variety of symmetrical trisheterocycles bis-oxazolyl/thiazolyl/imidazolylacetamido-sulfonylmethyl 1,3,4-oxadiazoles and 1,3,4-thiadiazoles was prepared, and their antioxidant activity was studied. The compounds bisoxazolyl oxadiazole and bisoxazolyl thiadiazole having methyl substituent on the aromatic ring exhibited greater antioxidant activity than the standard ascorbic acid.

A new class of pyrazolyl/isoxazolyl-oxazolines and thiazolines was synthesized from simple substrate E-aroylethenesulfonylacetic acid methyl ester with the aid of the samarium(III) chloride catalyst and 1,3-dipolar cycloaddition methodology.

A new class of sulfonylmethane linked bisheterocycles were prepared and studied their antimicrobial activity.

A new class of sulfonamido bis heterocycles—pyrrolyl/pyrazolyl-oxadiazoles, thiadiazoles, and triazoles—were prepared from arylaminosulfonylacetic acid hydrazide and E-aroylethenesulfonylacetic acid adopting simple and versatile synthetic methodologies.

A new class of arylsulfonylethylsulfonylmethyl oxazolines and thiazolines were prepared using multistep, one-pot methodologies exploiting lanthanide alkoxides and under microwave irradiation. The microwave method provides an excellent approach in a single step with high yields.

A new class of bis heterocycles—sulfone linked pyrazolyl oxadiazoles thiadiazoles were prepared from E-phenylsulfonylethenesulfonylacetic acid and studied their antimicrobial activities. J. Heterocyclic Chem., (2011).

The reactivity of barbituric/thiobarbituric ketene dithiolates with bromoacetic ester and phenacyl bromide is studied. J. Heterocyclic Chem., (2011).

A new class of pyrazolidinediones, isoxazolidinediones, pyrimidinetriones, and thioxopyrimidinediones were synthesized by the reaction of Michael adduct, dimethyl 2-(1′,2′-diarylsulfonyl)ethylmalonate with different nucleophiles, hydrazine hydrate, hydroxylamine hydrochloride, and urea derivatives. J. Heterocyclic Chem., 2011.

New and novel sulfone linked bis heterocycles_ bis pyrroles and pyrrolyl pyrazolines are prepared from 1-arylsulfonyl-2-styrylsulfonylethenes by 1,3-dipolar cycloaddition methodology.

Some pyrazoline, isoxazoline and pyrimidine derivatives were synthesized from ketene dithioacetals using appropriate nucleophiles.

Novel spiro heterocycles, substituted spiro-pyrimidine, pyrazole and isoxazole compounds are prepared by the cyclocondensation of 4-oxocyclohexane gem-dicarboxylates and cyano esters with nucleophiles.

A new class of five membered heterocycles, thiadiazoles, triazoles and oxadiazoles were prepared from sulfonyl acetic acids via acid hydrazides.

A new class of spiro-pyrimidines, pyrazoles and isoxazoles are prepared by nucleophilic reaction of 3,5-diaroyl-2,6-diaryl-piperidine-4,4-dicarbonitrile (1), 3,5-diaroyl-2,6-diaryl-tetrahydropyran-4,4-dicarbonitrile (2) and 3,5-diaroyl-2,6-diaryl-tetrahydrothiopyran-4,4-dicarbonitrile (3) with urea, N,N'-dimethyl urea, thiourea, hydrazine hydrate and hydroxylamine hydrochloride.

Novel 2-pyrazolines were obtained by the cycloaddition of diazomethane to bis(arylsulfonylethenyl)-sulfones (3) and 1-arylsulfonyl-2-styrylsulfonylethenes (7). Dehydrogenation of 2-pyrazolines with chloranil gave pyrazoles.

A new class of 3,4-disubstituted pyrroles has been prepared by the reaction of 1-aroyl-2-arylsul-fonylethenes and 1,2-diarylsulfonylethenes with tosyl methyl isocyanide.