Chlorine-free copper-catalyzed oxidative synthesis of 1,3,4-oxadiazoles with molecular oxygen as the sole oxidant

Chlorine-free is not only one of the new concepts of green chemistry, but also a problematical task for chemical processes in industrial utility. During the past several decades, we devoted ourselves to the study of chlorine-free organic synthesis. Herein, we describe an efficient chlorine-free copper-catalyzed oxidative approach providing 1,3,4-oxadiazoles in good yields from readily available starting materials. This transformation requires only a green and inexpensive reagent to afford the structurally useful motifs, and has a broad functional groups tolerance.