Synthesis of Isoxazol-5-One Derivatives Catalyzed by Amine-Functionalized Cellulose

In this contribution, the propylamine-functionalized cellulose (Cell-Pr-NH2) was employed as the catalyst in the three-component reaction between hydroxylamine hydrochloride, various type of aryl/heteroaryl aldehydes, ethyl acetoacetate/ethyl 4-chloroacetoacetate/ or ethyl 3-oxohexanoate. The results of these experiments were the formation of 3,4-disubstituted isoxazol-5(4H)-one heterocycles. The desired five-membered heterocyclic compounds were obtained in good to high yields at room temperature. The investigation of different solvents led us to the conclusion that water is the best solvent to perform the current one-pot, three-component reactions. Attempts to find the optimum catalyst loading clearly showed that 14 mg of Cell-Pr-NH2 seems to be sufficient to carry out the reactions. This method has highlighted some principles of green chemistry including less waste generation, atom economy, use of water as an environmentally friendly solvent, and energy saving. Purification without chromatographic methods, mild reaction conditions, simple work-up, low-cost reaction medium, saving time, and obtainable precursors are other notable features of this one-pot fashion.