Montmorillonite clay Cu(II) catalyzed domino one-pot multicomponent synthesis of 3,5-disubstituted isoxazoles

A simple and efficient one-pot multicomponent approach for the synthesis of 3,5-disubstituted isoxazoles directly from corresponding aldehydes and terminal alkynes using recyclable montmorillonite clay supported Cu(II)/NaN3 catalytic system under aqueous conditions have been developed. The 'domino' one-pot MCR approach involves hydroxyamination of aldehydes followed by chlorination and then generation of reactive 'nitrile oxide' which undergoes 1,3-dipolar cycloaddition with alkynes to produce 3,5-disubstituted isoxazoles. The method is operationally simple, regioselective, economical, and possesses excellent functional group compatibility to synthesize structurally diverse isoxazoles in good yields.