Synthesis of Assemblies of Isoxazole and Azoles Based on 1,3-Dipolar Cycloaddition Reaction of Enamines with Nitrile Oxides

Abstract

2-(1,2,3-Thiadiazol-5-yl)enamines and 3-(1,2,3-triazol-4-yl)enaminones react with arylhydroxamoyl chlorides at room temperature with the exclusive formation of 3-aryl-4-(1,2,3-thiadiazol-5-yl)- and [4-(1,2,3-triazol-4-yl)carbonyl]isoxazoles in high yields. The proposed mechanism includes in situ generation of nitrile oxides, which participate in the (3+2)-dipolar cycloaddition reactions leading to the formation of the isoxazole ring.