Facile Synthesis of Unsymmetrical 2,5-Disubstituted 1,3,4-Oxadiazoles by Cyclization of gem-Difluoroalkenes with Acyl Hydrazides

A mild and efficient method for the synthesis of unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles by condensation of gem-difluoroalkenes with acyl hydrazides was developed. The cyclization reaction proceeds smoothly with the assistance of Cs2CO3, affording a variety of 1,3,4-oxadiazoles in good to excellent yields. The reaction also exhibits a broad substrate scope and good functional group compatibility.