REACTION OF 2,2-DIPHENYLQUINOLINE-NITROXIDE RADICALS WITH NO-RELEASING SIN-1 (3-MORPHOLINOSYDNONIMINE)

The nitroxide radicals 1 are suitable traps for nitric oxide (NO.) rel eased from SIN-1 under aerobic conditions. Besides the stable products 2, 3, and 4, the relatively unstable nitroxides 5 are formed in this reaction, the latter decomposing to the stable derivatives 3, 6, and 7 . 7a is also formed by reaction of 1a with Fenton's reagent. 7b is syn thesized unequivocally by alkaline ferricyanide-oxidation of the nitro xide 8. Formation of compounds 2-5 is discussed in relation to relativ e reactivity of 1 towards nitric oxide (NO.) and nitrogen dioxide (NO2 (.)), respectively.