Rana Krishna Pal Singh

Electrosynthesis and screening of novel 1,3,4-oxadiazoles as potent and selective antifungal agents

The electrochemical oxidation of aldehyde-N-aroylhydrazone has been studied in the presence of NaClO4 as supporting electrolyte in MeOH solution using cyclic voltammetry and controlled potential electrolysis. The results indicate that intramolecular cyclization of aldehyde-N-aroylhydrazone has been successfully performed at a platinum electrode in an undivided cell with good yields of the corresponding 1,3,4-oxadiazoles at ambient conditions. The reaction products were characterized by spectroscopic methods and a mechanism was deduced from voltammetry studies. The antifungal activity of the synthesized compounds was evaluated on Fusarium oxysporum, Alternaria solani, Candida albicans and Aspergillus niger. The results revealed that all the synthesized compounds have significant antifungal activity against the tested fungi. Among the synthesized derivatives 7b, 7d, 7g, 7h, 7i, 7j and 7r were found to be the most effective antifungal compounds.

Electrochemical oxidation of aldehyde- N -arylhydrazones into symmetrical-2,5-disubstituted-1,3,4-oxadiazoles

A convenient, efficient and one-pot synthesis of chemically and pharmaceutically interesting symmetrical-2,5-disubstituted-1,3,4-oxadiazoles is reported. The protocol involves anodic oxidation of aldehyde-N-arylhydrazones in anhyd. MeCN–LiClO4. Constant potential electrolysis carried out in an undivided cell and platinum electrodes leads to the formation of the corresponding oxadiazoles under ambient condition and the mechanism was deduced from voltammetry studies. The reaction proceeded smoothly with high atom economy.

A convenient electro-catalyzed multicomponent synthesis of 4H-thiopyran derivatives

An environmentally benign synthesis of substituted 4H-thiopyrans was carried out by the condensation of aromatic aldehydes, malononitrile, carbon disulfide and primary amines. Constant potential electro synthesis was carried out in an undivided cell at room temperature in the presence of lithium perchlorate as a supporting electrolyte. Clean synthesis, use of electricity instead of chemical reagents and atom economy are attractive features of the present protocol.

Electrophoretic studies on mixed complexes metal-hippuric acid-nitrilotriacetate

In the present communication the ionophoretic technique has been used for the study of Fe(III), Cu(II), Ni(II), and Co(II)-hippuric acid binary and Fe(III), Cu(II), Ni(II), and Co(II)-hippuric acid-NTA ternary complexes (NTA — nitrilotriacetic acid). The stability constants of metal-hippuric acid binary complexes are found to be 103.54, 102.95, 102.77, and 102.70 and the stability constants of metal-hippuric acid-NTA ternary complexes have been found to be 106.16, 106.06, 106.01, and 105.90 for Fe(III), Cu(II), Ni(II), and Co(II) complexes, respectively, at μ = 0.1 M (HClO4) and 25°C.

Electrochemical behaviour of aldehyde- N -arylhydrazones at platinum electrode and their characterization

A series of chemically and pharmaceutically interesting 2,5-disubstituted-1,3,4-oxadiazoles were efficiently synthesized from the anodic oxidation of aldehyde-N-arylhydrazones at platinum anode by using NaClO4 as supporting electrolyte in MeOH solution under controlled potential electrolysis at room temperature. The products were characterized by spectroscopic methods and a mechanism was deduced from voltammetry studies. The salient features of this protocol are mild reaction conditions, short reaction time, accelerated rate, high yield and simple work-up procedure.