Application of Fe3O4@Chitosan–SO3H nanoparticles as efficient catalyst for synthesis of 4H-isoxazol-5-ones in aqueous medium

Isoxazoles are a class of heterocyclic compounds having a remarkable number of applications and have been demonstrated to be very versatile building blocks in organic synthesis [1]. They have a wide range of biological activities including hypoglycemic, analgesic, antiinflammatory, anti-bacterial and HIV-inhibitory activities, as well as some agrochemical properties such as herbicidal and soil fungicidal activities [2]. Isoxazoles have also been used as dyes, electric insulating oils and high temperature lubricants. The key feature of these heterocycles is that they possess the typical properties of an aromatic system but contain a weak nitrogen-oxygen bond which is a potential site of ring cleavage under certain reaction conditions, particularly in reducing or basic conditions. Thus, isoxazoles are very useful intermediates, since the ring system stability allows the manipulation of substituents to give functionally complex derivatives [3]. Among the several methodologies for synthesis of this compounds, using of heterogeneous magnetic catalysts in multicomponent reactions have been widely considered. Herein, we report the using of sulfonated magnetic chitosan (10 mol%) for synthesis of 4H-isoxazol-5-ones via one-pot three-component condensation of various aromatic aldehydes, hydroxylamine hydrochloride and 1,3-dicarbonyls at room temperature in aqueous medium (Figure 1).