Green oxidative cyclization to access 2,5-disubstituted-1,3,4-oxadiazoles from aldehydes and hydrazide derivatives using FeBr3 catalyst and hydrogen peroxide

2,5-disubstituted-1,3,4-oxadiazoles Oxidative cyclization of aldehydes and hydrazide derivatives to access 2,5-disubstituted-1,3,4-oxadiazoles has been developed using a catalytic amount of FeBr3 in the presence of aqueous hydrogen peroxide as an oxidant. By synthesizing 35 examples of 2,5-disubstituted 1,3,4-oxadiazoles, this approach was demonstrated to have good features including broad scope, mild conditions, air/water tolerance, and simple operation. More importantly, it can be expected to find wide applications in organic synthesis.