Development of the HERON Reaction: A Historical Account

This account describes the discovery and development of the HERON reaction, a reaction with special connection to the Heron Island Conferences on Reactive Intermediates and Unusual Molecules. This modern named' reaction describes an unusual rearrangement of bisheteroatom-substituted amides RCON(X)(Y) whereby the more electron deficient group, X, migrates from nitrogen to the carbonyl carbon giving an acyl derivative, RC(O)X, and Y-stabilised nitrenes. In it, the origins, mechanistic elucidation, and theoretical validation are described in more or less chronological order. Along that time line we introduce the concepts of anomeric amides', amidicity' in anomeric amides, and their role in the HERON reaction. All known versions of the reaction that have since been discovered are outlined and a basic understanding of the relative roles of reduced resonance and the anomeric driving force, both functions of the heteroatom substituents at the amide nitrogen, are quantified.