• AJAY KUMAR KARIYAPPA

      Articles written in Journal of Chemical Sciences

    • Synthesis, characterization and antioxidant activity studies of new coumarin tethered 1,3,4-oxadiazole analogues

      VAGISH CHANNA BASAPPA SUDEEP PENUBOLU DILEEP KUMAR ACHUTHA AJAY KUMAR KARIYAPPA

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      The present work describes the synthesis of a series of substituted 3-(5-phenyl-1,3,4-oxadiazol-2-yl)-2H-chromen-2-ones 7(a–j) using substituted aldehydes with analogues of hydrazine hydrates by grinding technique in the presence of Iodine which helps in the cyclization process. The structures of the synthesized compounds were elucidated by spectroscopic techniques such as IR, 1H NMR, 13C NMR, and LCMS. The comparative antioxidant property (using DPPH and hydroxyl radical scavenging) has been studied with the synthesized compounds 7(a-j) and the standards. Compounds 7d and 7i show the prominent radical scavenging activity.

      Synopsis: Series of ten new coumarin-oxadiazole hybrids synthesized in three steps starting from salicylaldehyde and diethylmalonate. All new compounds were spectroscopically characterized. The results of radical scavenging activities show that, two compounds of the series 7d and 7i displayed potent DPPH and hydroxyl radical activity comparable to the standards employed, and therefore acts as antioxidant leads.

    • Design, synthesis of coumarin tethered 1,2,3-triazoles analogues, evaluation of their antimicrobial and α-amylase inhibition activities

      VAGISH CHANNABASAPPA KARTHIK KUMARA AJAY KUMAR KARIYAPPA

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      A vital transition metal Cu(II) ion catalyzed reaction was encrypted in the synthesis of newcoumarin tethered triazoles 6(a-i) using the substituted azidobenzenes and substituted 3-acetyl-2H-chromen-2-ones in the presence of oxidative potassium persulfate, and DMF as a solvent and C5-H source. Thestructure proofs of the new compounds were provided by the spectral analysis. The in vitro antimicrobialactivities of the target compounds indicate that compounds 6c and 6g of the series have potent inhibitionagainst the tested bacteria and fungi species. Among the synthesized series compound 6g was found potentfor a-amylase inhibition activity.

      Synopsis. Dimethylformamide was used as a solvent and C5-H source reagent in the synthesis of triazole rings. The reaction of substituted azides, 2(a-e) and substituted 3-acetyl-2-oxo-2H-chromenes, 5(a-b) in the presence of a catalytic amount of Cu(NO3)2 and an oxidant K2S2O8 was carried out under reflux conditions using an oil bath for 36-48 h. From the reaction mixture, the target compounds 6(a-i) were extracted with ethyl acetate. The synthesized coumarin-triazole hybrids, 6(a-i) were spectroscopically characterized and evaluated for antimicrobial and α-amylase inhibitory activities.

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