A thermal fragmentation of 1,2,4-oxadiazole-4-oxides to nitriles and nitrosocarbonyls

1,2,4-Oxadiazole-4-oxides undergo clean thermal cleavage in refluxing chlorobenzene or xylene to nitriles and nitrosocarbonyl intermediates, which are either trapped with suitable olefins to afford ene adducts or dimerize and rearrange to anhydrides.