Abstract 1, 3-Cycloadditions of stable nitrile oxides 2 to nitrilium salts 1 afford high yields of 3, 4, 5-trisubstituted 1, 2, 4-oxadiazolium salts 3. N-Hydroxycarboximidoyl chlorides 4 add to nitrilium salts 1 to give isolable [(chloroalkylidene) aminooxyalkylidene] ammonium salts 5. A thermal stereomutation around the C= N+ bond is observed. On heating neat or in solution most compounds 5 cyclize to oxadiazolium salts 3. In cases where decomposition of 5 is ...
