Conversion of Aliphatic Amides into Amines with benzene. Scope of the Reaction

Article abstract of DOI:10.1021/jo00196a031

The reagent benzene, PIFA, brings about the facile oxidative rearrangement of aliphatic amides to amines in mildly acidic (pH 1-3) mixed aqueous-organic solvents.Aromatic amines are further oxidized by the reagent and therefore cannot be prepared by this method.The rearrangement, which is in effect an "Hofmann rearrangement", occurs with complete retention of configuration in the migrating group, and the rate of the reaction follows approximately the migratory aptitudes of the migrating groups determined for other similar reactions.Isocyanates are intermediates in the rearrangement but are rapidly hydrolyzed to the product amines under the mildly acidic conditions.The acidic conditions protect the product amines from reacting with the isocyanate intermediates and forming ureas.The reaction is accelerated by addition of pyridine to a pH of approximately 3.The scope of the reaction is discussed.