One-flask transformation of secondary amines to nitrones by oxidation with hydrogen peroxide mediated by triscetylpyridinium tetrakis oxodiperoxotungsto-phosphate (PCWP). Some mechanistic considerations

Acyclic and cyclic secondary amines are oxidized to nitrones by H2O/PCWP system in water/chloroform under phase transfer catalysis conditions. The different acidities of the protons of the carbon atoms alpha to the nitrogen might be responsible for the identity and of the steroechemistry of the formed nitrone. The presence of an aromatic ring such as benzene directly linked to the nitrogen represents a limitation, since in this case many oxidation products are observed. As far as the mechanistic aspects are concerned, it is suggested that the oxidation process might be started by a nucleophilic attack of the amine to the peroxidic oxygens of the peroxometal complex or by a single electron transfer from the amine to the oxidant.