Deepak K. Aneja

A facile iodine(III)-mediated synthesis of 3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-a]pyridines via oxidation of 2-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-1-(pyridin-2-yl)hydrazines and their antimicrobial evaluations

Background Fused heterocyclic 1,2,4-triazoles have acquired much importance because of their interesting biological properties. Although a number of methods have been reported in the literature which includes oxidation with phosphorus oxychloride, lead tetraacetate, bromine, etc., hypervalent iodine reagents have emerged as reagents of choice for various synthetically useful transformations due to their low toxicity, ready availability and ease of handling. Results A series of new 3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-a]pyridines 4 has been conveniently synthesized by oxidative cyclization of 2-(3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-1-(pyridin-2-yl)hydrazines 3 promoted with iodobenzene diacetate under mild conditions (up to 90% isolated yields). All the new compounds were tested in vitro for their antimicrobial activity. Conclusions Iodine(III)-mediated oxidative approach has offered an easy access to new 3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-a]pyridines 4. The antibacterial and antifungal activities of newly synthesized compounds have proved them potent antimicrobial agents.

Design, synthesis, computational and biological evaluation of some new hydrazino derivatives of DHA and pyranopyrazoles.

Two series of compounds namely, 4-aryl/heteroaryl hydrazino-3-acetyl-6-methyl-2H-pyran-2-ones (4a-4j) and pyrano[4,3-c]pyrazoles (6a-6e and 6g) were synthesized starting from 3-acetyl-4-chloro-6-methyl-2H-pyran-2-one (2). Estimation of pharmacotherapeutic potential, possible molecular mechanism of action, toxic/side effects and interaction with drug-metabolizing enzymes were made for the synthesized compounds on the basis of prediction of activity spectra for substances (PASS) prediction results and their analysis by PharmaExpert software. COX inhibition predicted by PASS was confirmed by experimental evaluation and validated via docking studies. Out of all the compounds, compounds 4h, 4j, 6e, 6g exhibited good anti-inflammatory activity, whereas compounds 4b, 4c, 4h, 4i, 4j, 6b, 6e, 6g showed excellent analgesic activity compared with standard drug Diclofenac sodium.

Synthesis of new pyrazolyl-2, 4-thiazolidinediones as antibacterial and antifungal agents

Background Thiazolidine-2, 4-diones (TZDs) have become a pharmacologically important class of heterocyclic compounds since their introduction in the form of glitazones into the clinical use for the treatment of type 2 diabetes. TZDs lower the plasma glucose levels by acting as ligands for gamma peroxisome proliferators-activated receptors. In addition, this class of heterocyclic compounds possesses various other biological activities such as antihyperglycemic, antimicrobial, anti-inflammatory, anticonvulsant, insecticidal, etc. TZDs are also known for lowering the blood pressure thereby reducing the chances of heart failure and micro-albuminuria in the patients with type 2 diabetes. Results We have described herein the synthesis of three series of compounds, namely, ethyl 2-((Z)-5-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-2, 4-dioxothiazolidin-3-yl)acetates (4), methyl 2-((Z)-5-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-2, 4-dioxothiazolidin-3-yl)acetates (5), and 2-((Z)-5-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-2, 4-dioxothiazolidin-3-yl)acetic acids (6). The compounds 4 and 5 were synthesized by Knoevenagel condensation between 3-aryl-1-phenyl-1H-pyrazole-4-carbaldehydes (1) and ethyl/methyl 2-(2, 4-dioxothiazolidin-3-yl)acetates (3, 2) in alcohol using piperidine as a catalyst. The resultant compounds 4 and 5 having ester functionality were subjected to acidic hydrolysis to obtain 6. All the new compounds were tested for their in vitro antibacterial and antifungal activity. Conclusions Knoevenagel condensation approach has offered an easy access to new compounds 4-6. Antimicrobial evaluation of the compounds has shown that some of the compounds are associated with remarkable antifungal activity. In case of antibacterial activity, these were found to be effective against Gram-positive bacteria. However, none of the compounds were found to be effective against Gram-negative bacteria.

Synthesis and biological evaluation of dihydroindeno and indeno [1,2-e] [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines as antimicrobial agents

Two series of compounds namely, dihydroindeno and indeno [1,2-e] [1,2,4]triazolo [3,4-b] [1,3,4]thiadizines (9a-l & 11a-l) were synthesized by cyclocondensation between α-bromoindanones (7a-b) or/and α,α-dibromoindanones (8a-b) and various 3-alkyl/aryl-4-amino-5-mercapto-1,2,4-s-triazoles (3a-f) in methanol with an aim to explore their effect on in vitro growth of microorganism causing microbial infection. In vitro antibacterial activity was performed against four strains namely, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and antifungal activity against three fungal strains namely, Aspergillus niger, Aspergillus flavus, Penicillium species. Of all the compounds screened for activity some of the compounds were associated with considerably higher antibacterial and antifungal activity than commercial antibiotics.

Synthesis and antimicrobial activities of some new 5-((3-(aryl)-1-phenyl-1H-pyrazol-4-yl)methylene)-3-phenylthiazolidine-2,4-diones

A series of nine new compounds of 5-((3-(aryl)-1-phenyl-1H-pyrazol-4-yl)methylene)-3-phenylthiazolidine-2,4-diones was synthesized by Knoevenagel condensation of various 3-(aryl)-1-phenyl-1H-pyrazole-4-carbaldehydes with 3-phenylthiazolidine-2,4-dione in ethanol in the presence of piperidine as a catalyst. The reaction afforded the desired products in good yields. All the nine compounds were screened for their in vitro antibacterial (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli) and antifungal (Aspergillus niger and A. flavus) activity. Biological activities of these compounds were compared with those of commercially available antibiotics, ciprofloxacin and antifungal agent fluconazole. Two compounds 3e and 3i were found to be most effective against S. aureus and B. subtilis. Out of the nine compounds tested for antifungal activity, five, 3c–f and 3h showed more than 50% inhibition against the A. flavus, whereas the three compounds 3a, 3d and 3f showed more than 50% inhibition against A. niger.