Environmentally Benign and Expeditious Access to 4‐Aryl Methylene‐isoxazole‐5(4H)‐Ones Using Magnetically Separable Nanoparticles

Abstract An environmentally benign and expeditious protocol was developed for the one‐pot multicomponent synthesis of 4‐aryl‐3‐methylisoxazol‐5(4H)‐ones by the condensation of aldehyde, hydroxyl amine hydrochloride, and ethyl acetoacetate in 50% aq. ethanol at 50 °C. The reaction was catalyzed by magnetically separable carbon microspheres co‐decorated with nanosized iron sulfide and magnetite nanoparticles in 10 wt% amount. The FeS 1‐x ‐Fe 3 O 4 /C nanocatalyst was prepared from iron(III) sulfate loaded iminodiacetate group functionalized styrene‐divinylbenzene based ion exchanger by pyrolysis reaction performed at 600 °C for 4 h. The use of magnetically separable heterogeneous catalyst, aqueous ethanol, short reaction time (30 min), and nonchromatographic purification methods are the striking features of the developed protocol. The isolated yield of the condensation products varied between 81% and 96%. Furthermore, the protocol exhibits high functional group tolerance and includes the use of noncorrosive, nonhazardous reaction conditions affording the product in excellent yields and short reaction time.