The HERON Reaction: Origin, theoretical background, and prevalence

The origin of the HERON reaction is reviewed from a historical perspective and shown to have its foundation in the unusual properties of bisheteroatom-substituted amides, so-called anomeric amides. The reaction involves migration of anomerically destabilized oxo-substituents on an amide nitrogen to the amide carbon and dissociation of the amide bond. Computational work providing a theoretical basis for the reaction is presented, together with physical organic measurements that support results therefrom. The rearrangement has been observed in a number of chemicaltransformations of N-alkoxy-N-aminoamides, reactions of 1-acyloxy-1-alkoxydiazenes, N-alkoxy-N-aminocarbamates, Nalkoxyhydroxamicacids, as well as in the gas-phase reactions of N-acyloxy-N-alkoxyamides.