Efficient oxidative cyclization of N -acylhydrazones for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles using t -BuOI under neutral conditions

An efficient procedure for the oxidative cyclization of N -acylhydrazones was developed utilizing tert -butyl hypoiodite ( t -BuOI), which is generated in situ from t -BuOCl and NaI. A variety of 2,5-disubstituted 1,3,4-oxadiazoles were synthesized in high yields within short reaction time. The method is also suitable for cyclization of N -acylhydrazones derived from heterocyclic aldehydes and aliphatic aldehydes. Mild reaction conditions and simple workup operations make the procedure a good alternative for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles.