Overview of the Mechanistic Work on the Concerted Metallation–Deprotonation Pathway

Abstract The cleavage of aromatic C–H bonds promoted by a metal and an intramolecular base has been described over 50 years ago. Herein, discussion of selected mechanistic studies of this transformation will be presented. The basic ligand on the metal was proven to play a pivotal role in the C–H bond cleavage step and evidence of a single operative concerted metallation–deprotonation mechanism unifies the different mechanistic studies.