Convenient Ultrasound Promoted Synthesis of 2-Aryl Benzoxazoles in the Presence of KCN/Ionic Liquid as an Efficient Catalyst under Mild Conditions

A simple and efficient procedure has been developed for the synthesis of 2-aryl benzoxazoles using one-pot reaction of 2-aminophenol and aromatic or heteroaromatic aldehydes in the presence of KCN/1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) as a catalyst under ultrasound irradiation. 2-Aryl benzoxazoles were achieved in excellent yields and high purities in short reaction times. This protocol was shown to have some advantages such as readily reaction method, simplicity of the workup procedure, low cost, eco-friendly catalyst, and mild reaction conditions.