Oxadiaziridines, the Cyclic Form of an Azoxy Group. Synthesis, Valence Isomerism, and Reactivity

The photolysis of alkyl azoxy compounds RNN(0)R (11a, R = t-butyl; 11b, R = n-butyl) in pentane affords a new three-membered-ring heterocycle, an oxadiaziridine (12a, R = t-butyl; 12b, R = n-butyl). The oxadiaziridines revert to the azoxy compounds, t_1/2 at 28° ≃ 5 hr. The isomerization is catalyzed by acids (fivefold acceleration for 12a by 1.7 M Cl₂CHCOOH in CCl₄) and shows a slight solvent effect (k_rel for 12a in CCl₄, CH₃OH, CH₃NO₂: 1, 2, 2.5). Compound 12a is reduced to the corresponding azo compound by acidified NaI in acetone; it is generally unreactive toward LiAlH₄ or CH₃Li. Compounds 11b and 12b are reduced to the corresponding azo compound by LiAlH₄. Compound 12b is reduced by CH₃Li to azobutane and butyraldehyde n-butyl-hydrazone; 11b reacts with CH₃Li to afford 1-methylazobutane.