A mild convenient ultrasound assisted synthesis of 2-aryl benzoxazoles catalyzed by KCN/MWCNT as an efficient heterogeneous nanocatalyst

Abstract

In this research, it was presented a simple and efficient method for one-pot synthesis of 2-arylbenzoxazoles which were directly synthesized from o-aminophenol and aromatic or heteroaromatic aldehydes catalyzed by MWCNTs supported KCN in DMF media under ultrasound irradiation. MWCNTs supported KCN was prepared under ultrasound irradiation and was characterized by XRD and FT-IR techniques. The catalyst was used as a convenient, eco-friendly, easy available and highly efficient heterogeneous nanocatalyst which combined with ultrasound irradiation for synthesis of benzoxazole derivatives such as; 2-(2-hydroxyphenyl)-1, 3-benzoxazole (2, 96%), 2-(4-chlorophenyl)-1,3-benzoxazole (5, 94%) and 2-(2-thiophen-2-yl)-1,3-benzoxazole (12, 92%). Aldehydes having either electron-donating or withdrawing groups were used to afford 2-arylbenzoxazoles as target products in short reaction times with excellent yields and high purities. Also, this procedure has advantages such as; simplicity of the workup, reusability of catalyst, low cost and mild conditions. The structure of the obtained products was characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectral data.