• KALEGOWDA SHIVASHANKAR

      Articles written in Journal of Chemical Sciences

    • Synthesis of aminomethylphenol derivatives via magnetic nano Fe3O4 catalyzed one pot Petasis borono-Mannich reaction

      PRIYA CHACKO KALEGOWDA SHIVASHANKAR

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      A novel library of aminomethylphenol has been developed using magnetic Fe3O4nanoparticles via Petasis borono-Mannich reaction of salicylaldehydes, secondary amines and phenyl boronic acids. This one-pot protocol features mild reaction conditions, excellent yields in short reaction times, readily available starting materials, good functional group tolerance and reusability of the catalyst for four consecutive cycles without significant loss in its activity.

    • Zinc chloride catalyzed multicomponent synthesis of pyrazolopyridocoumarin scaffolds

      DEVADAS SHAMALA KALEGOWDA SHIVASHANKAR CHANDRA MADEGOWDA MAHENDRA

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      An efficient synthesis of a series of pyrazolopyridocoumarins is reported by condensation of 4hydroxycoumarin, benzaldehydes and 1-alkyl-5-amino-pyrazoles in the presence of 10 mol% zinc chloride in ethanol under reflux conditions through one-pot reaction. The significant attraction of this protocol is being a simple procedure, mild reaction condition, and excellent yield. The molecular structure of the compound (4e) is established by single crystal X-ray structure determination.

    • KSCN and K2CO3 mediated one-pot synthesis of cyclopropanyl coumarin derivatives

      MOHAMMED IMRANKHAN KALEGOWDA SHIVASHANKAR

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      A novel and efficient one-pot method has been developed for the synthesis of cyclopropanes by the cyclization of 4-bromomethylcoumrains, benzaldehydes and active methylene groups in 1:1 acetonitrile and water solvent in the presence of KSCN and K2CO3 as a catalyst at room temperature for 2-5 h. The significant attraction of this procedure is environmentally benign, simple procedure, the ready accessibility of the catalyst, excellent yield and mild reaction conditions. The structure of the target molecule (4b) was confirmed by X-ray diffraction.

      Synopsis: A library of novel cyclopropanyl coumarin derivatives were synthesised in good yields through one-pot three-component cyclization of 4-bromomethylcoumarins, benzaldehydes and active methylene groups. The structures of the synthesised compounds were confirmed by spectral methods viz. IR, 1H NMR, 13C NMR, mass spectral analysis and X-ray diffraction studies.

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