However, nickel peroxide was found to be a mild and effective reagent for the preparation of the isoxazole 3a.

Keywords: 2,4,6-tribromonitrosobenzene, spin trapping, nickel peroxide.

Nickel peroxide again proved an effective dehydrogenating agent to convert the isoxazolines 2b and 8 to the isoxazoles 3b and 9, respectively.

Oxidation with nickel peroxide gives iminoquinone methide 10, to which methanol is added in a conjugate sense and in the sterechemistry represented by formula 11.

By means of static-sample studies involving the thermal decomposition of symmetric azo compounds and the oxidation of substrates with nickel peroxide, we have characterized by electron paramagnetic resonance 12 spin adducts of 2,4,6-tribromonitrosobenzene, 1, in benzene at 25 °C.