Direct synthesis of 3,5‐diaryl‐1,2,4‐oxadiazoles using 1‐(2‐oxo‐2‐arylethyl)pyridin‐1‐iums with benzamidines

Abstract

An efficient domino protocol for the synthesis of 1,2,4-oxadiazole derivatives from readily available 1-(2-oxo-2-arylethyl)pyridin-1-iums and amidine hydrochlorides was developed. In this practical approach, N-acyl amidine precursors were formed firstly via a simple nucleophilic substitution, without the purification of N-acylamidine intermediates, and the following intramolecularly dehydrative cyclization gave 1,2,4-oxadiazole derivatives in the presence of I 2 / K 2 CO 3 /DMSO, which exhibited excellent functional group tolerance and proceeded under simple experimental conditions.