Oxidative phosphonylation of aromatic compounds

Abstract

Aryl phosphonates can be prepared in good yield from the respective arenes and tri- or dialkyphosphites by either chemical or anodic oxidation. The anodic oxidation proceeds either via phosphinium radical cations, which then attack the arenes electrophilically, or via arene radical cations, which add the trialkylphosphite as nucleophile. Aryl phosphonates are also obtained in good yield by chemical oxidation with peroxodisulfate/AgNO3 in acetonitrile/water or glacial acetic acid. The diethylphosphinium radical cation, formed from diethylphosphite by oxidation with Ag(II), is supposed to be the reactive species in this process. Raising the silver salt concentration leads to an increase in polyphosphonylation. Selectivity ratios were determined for the oxidative phosphonylation process.