Facile and green synthesis of 3,5-disubstituted isoxazoles using doped nano-sized copper(I) oxide (Cu2O) on melamine–formaldehyde resin as an efficient nano-catalyst under ultrasonic irradiation

In the present research, doped nano-sized copper(I) oxide (Cu2O) on melamine–formaldehyde resin as a heterogeneous and efficient nano-catalyst has been employed for green and mild synthesis of 3,5-disubstituted isoxazoles under ultrasonic irradiation. In this approach, 1,3-dipolar cycloaddition reaction of structurally diverse alkynes and nitrile oxides (in situ generated from imidoyl chlorides) in the presence of this heterogeneous nano-catalyst under ultrasonic irradiation in water as a green solvent affords 3,5-disubstituted isoxazole derivatives in good to excellent yields. The use of green solvent, mild reaction conditions, short reaction time, recoverability and reusability of catalyst, and simple purification process are important advantages of the present method.