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.