Reaction of aromatic amides with phenyl iodosylacetate: an oxidative rearrangement

Abstract

The oxidative rearrangement of primary amides with phenyl iodosylacetate (PIA) yields the corresponding acylamines in acetic acid. The kinetics of the reaction of PIA with a number of substituted benzamides have been studied in solvent acetic acid and also in acetic acid–water mixtures. Electron-releasing substituents in the benzene rIng accelerate the rate of the reaction while electron withdrawing substituents retard the rate. The Hammett ρ value is –0.81, indicative of an electron deficient transition state. The results have also been analysed using the Yukawa–Tsuno equation. A mechanism involving the formation of an iodine (III)–amide complex which rearranges in a concerted fashion to the isocyanate is proposed.