Efficient synthesis of isoxazole-5(4H)-ones and polyhydroquinolines using MMWCNTs-PIP and MMWCNTs-MOR

Abstract

Two efficient catalysts were designed and synthesized via a method therein piperazinium and morpholinium halides as ionic liquids were immobilized on magnetic MWCNTs through a poly(ethylene glycol) linker. A facile one-pot and four-component synthesis of polyhydroquinoline derivatives was conducted via the unsymmetric Hantzsch reaction using ethyl acetoacetate, ammonium acetate, dimedone and an aromatic aldehyde in the presence of MMWCNT-PEG-PIP in EtOH. Also, three-component synthesis of 3-methyl-4-arylmethylene isoxazole-5(4H)-ones was explored using ethyl acetoacetate, hydroxyl amine hydrochloride and an aromatic aldehyde in the presence of and MMWCNT-PEG-MOR in H₂O: EtOH (4:1). After the reaction was completed, external magnet was used to separate the magnetic catalyst. The recovered catalyst was reused for five runs without any decrease in catalytic activity. High yields, simple work-up, very high TOFs and using green solvent are advantages of this method. Antioxidant activity was investigated for all the synthesized polyhydroquinoline derivatives. Also, anti-bacterial activities of four isoxazole-5(4H)-ones were examined.