Formation of 2,3,6,8-tetraazabicyclo[3.2.1]oct-3-ene derivatives in reaction between 2-acyl-3-imidazoline 3-oxides and hydrazine and their oxidation to the corresponding nitroxyl radicals and 1,2,4-triazine 4-oxide

1. Reaction of 2-acyl-1-hydroxy-3-imidazoline 3-oxides with monosubstituted hydrazines leads to monosubstituted hydrazones, derivatives of 2-acyl-1-hydroxy-3-imidazoline 3-oxide, which on oxidation give stable nitroxyl radicals of the imidazoline series. 2. In the reaction between 2-acyl-3-imidazoline 3-oxides and hydrazine, an intramolecular cyclization takes place with the formation of a new heterocyclic system, 2,3,6,8-tetraazabicyclo[3.2.1]oct-3-ene. 3. The oxidation of 6,8-dihydroxy-4,5,7,7-tetraalkyl-1-R-2,3,6,8-tetraazabicyclo[3.2.1]oct-3-enes leads to bicyclic nitroxyl radicals, 8-hydroxy-4,5,7,7-tetraalkyl-1-R-2,3,6,8-tetraazabicyclo[3.2.1]oct-3-en-6 oxyls, which on oxidation give 1,2,4-triazine 4-oxides.