Application of nitroxyl radical derivatives to organic synthesis.

2, 2, 6, 6, -Tetramethylpiperidine-1-oxyl known as a stable radical is reduced to the hydroxylamine and is also oxidized to the oxoaminium salt. These redox reactions are reversible chemically. In this article we describe some application of nitroxyl radical to organic reactions based on its redox function.Hydroxylamine was demonstrated to work as a hydration reagent of nitriles to produce amides. Further, it was found that oxygen is reduced by an anion of hydroxylamine to give superoxide ion. Oxoaminium salt, an oxidized form of nitroxyl radical, oxidized hydroxide ion and alcohols to give selectively hydrogen peroxide and the corresponding carbonyl compounds, respectively. The redox systems using oxoaminium salt as a mediator were investigated. Further, we found that the polymeric mediator was superior to the monomeric mediator.