The chemistry of vinyl nitroxides

Abstract- Vinyl nitroxides (VNs) generated by oxidation of nitrones or the corresponding hydroxylamines are very reactive radicals. In contrast to VNs di-substituted at the B-position of the vinyl group those which are mono-substituted could not be observed directly by ESR with a few exceptions. Instead, their spin adducts with the precursor nitrones were detected. Dimerization of VNs occurs usually by bond formation between the two D-carbon atoms, frequent1 followed by a secondary reaction step. An unsymmetrical dimer formed by bon ing between the oxygen and the &carbon atom could be isolated in a single case. However, such OC-dimers are fre uently formed in a intermediate formation becomes cons icuous if they can undergo a subsequent reaction either bi- or tricyclic dimers. '!he latter dissociate in solution, usually even at room temperature, regenerating the VNs by breaking of four bonds. kinetically controlled reaction. Being usually less stable compared to t x e CC-dimers, their that gives a thermodynamical1 stab P e product. B-Acyl-B-aryl-disubstituted VNs for