1,3‐cycloaddition of substituted benzonitrile oxides to aliphatic nitriles. The kinetic effect of substituents

Abstract A previous study of the reaction of aromatic nitrile oxides with simple aliphatic nitriles, with the formation of 3,5‐disubstituted 1,2,4‐oxadiazoles, has been extended to a larger number of nitrile oxides. Sixteen new oxadiazole derivatives have been prepared and characterized. Cycloaddition rates have been measured in the temperature range from 50 to 80°. When considering the effect of substituents on the aromatic ring, roughly V‐shaped Hammett plots have been obtained, as already observed for other concerted 1,3‐cycloadditions.