Mild and Efficient Synthesis of 5-(2,2-difluoro-1-phenyl cyclopropyl)-N-substituted-1,3,4-oxadiazol-2-amines via Graphene Oxide as Catalyst under Ultrasonic Irradiation Conditions

摘要

We disclosed herein a series of novel 5-(2,2-difluoro-1-phenylcyclopropyl)- N-substituted-1,3,4-oxadiazol-2-amines from the reaction of 2,2-difluoro-1-phenylcyclopropane carbohydrazide and various isothiocyanates in the presence of graphene oxide (GO) and 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) under conventional and ultrasonic irradiation conditions. It was found that the reaction was completed in a short period of time with good to excellent yields by virtue of attributes offered by GO catalyst. Further, the reaction underwent smoothly in ethanol and ionic liquids. Noteworthy, GO can be recycled and reused for five cycles without considerable loss in activity. The oxidative activity and morphology of GO catalyst was confirmed by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) techniques.