Studies on Stable Free Radicals. IX. Peroxy Acid Oxidation of Hindered Secondary Amines to Nitroxide Radicals

摘要: The hindered secondary amines, 2,2,6,6-tetramethyl-4-oxopiperidine (II) and 1,9-diaza-2,2,8,8,10,10-hexamethyl-4-oxo-spiro[5.5]undecane (VI), were oxidized with m-chloroperbenzoic acid, the corresponding hydroxylamine (III) N-oxyl-hydroxylamine (VIII), respectively, isolated. further oxidation of III VIII peracid afforded nitroxide radical IV IX, in good yields respectively. stoichiometry reaction to was elucidated on basis ESR signal intensities products at various molar ratios III. An study 1-15N-labelled (XII) indicated that there an intramolecular hydrogen transfer between >N–OH >N–O · groups N-oxyl-hydroxylamines XII.