Metal free oxidation of vinamidine derivatives: a simple synthesis of α-keto-β-diimine ligands.

Oxidation of vinamidinium salts with meta -chloroperbenzoic acid is the key synthetic step towards new persistent 1,3-di(amino)oxyallyl radical cations. When applied to parent vinamidines, this protocol allows for a simple straightforward synthesis of α-keto-β-diimine ligands, for which no convenient synthesis was previously available.