A simplified procedure for preparing 3,5‐disubstituted‐1,2,4‐oxadiazoles by reaction of amidoximes with Acyl chlorides in pyridine solution

Abstract 3‐ R ‐5‐ R ′‐1,2,4‐Oxadiazoles are prepared in fair to good yield by short‐time, one‐pot reaction of an amidoxime, RC(NH 2 )NOH, with an acyl chloride, R'COCl, in pyridine solution. Precipitation of the oxadiazole occurs on diluting the pyridine reaction solution with water. Ordinary acyl chlorides can be used; they do not have to be unusually reactive to succeed in the one‐pot preparation. The procedure is simpler and more convenient than the conventional one, namely isolation and thermal rearrangement of an O ‐acylamidoxime.