The ortho-directed lithiation of aromatic carbamates and carbonates causes a migration of the substituent from the pendant O group to the adjacent C atom of the aromatic scaffold. This reaction, resulting in the formation of ortho-hydroxycarbonyl compounds, is widely known as the anionic Fries rearrangement, and is described in terms of the migrating group as a 1,3-O→C shift. The intramolecular mechanism allows for a control of regioselectivity by a metalation procedure. Commonly known for the migration of carbonyl groups, the scope has been extended in recent years to Si-, S- and P-based versions, known as the respective anionic sila-, thia- and phospho-Fries rearrangements. Examples of higher homologues, which are sparsely investigated, will also be discussed. Starting with aromatic substrates in the 1980s organometallic backbones, e.g. ferrocenes, have also been introduced, which opened the pathway for stereoselective processes of the Fries rearrangement. Furthermore, related conversions, such as 1,2-, 1,4- (homo-Fries), 1,5- (remote-Fries) and 1,6- as well as, e.g. N→C, and S→C migrations were reported and are included herein. The mechanisms for the Fries rearrangement and competing reactions, e.g. aryne formation, are discussed, based on, e.g., labeling experiments and DFT calculations. Redox-active ferrocenyl derivatives allowed for electrochemical investigations, revealing an influence of the electronic properties of the sandwich unit on the lithiation, rearrangement and post-functionalization behavior of the participating compounds.

A coupling-limited approach for the Ullmann reaction-like on-surface synthesis of a two-dimensional covalent organic network starting from a halogenated metallo-porphyrin is demonstrated. Copper-octabromo-tetraphenylporphyrin molecules can diffuse and self-assemble when adsorbed on the inert Au(111) surface. Splitting-off of bromine atoms bonded at the macrocyclic core of the porphyrin starts at room temperature after the deposition and is monitored by X-ray photoelectron spectroscopy for different annealing steps. Direct coupling between the reactive carbon sites of the molecules is, however, hindered by the molecular shape. This leads initially to an ordered non-covalently interconnected supramolecular structure. Further heating to 300 °C and an additional hydrogen dissociation step is required to link the molecular macrocycles via a phenyl group and form large ordered polymeric networks. This approach leads to a close-packed covalently bonded network of overall good quality. The structures are characterized using scanning tunneling microscopy. Different kinds of lattice defects and, furthermore, the impact of polymerization on the HOMO–LUMO gap are discussed. Density functional theory calculations corroborate the interpretations and give further insight into the adsorption of the debrominated molecule on the surface and the geometry and coupling reaction of the polymeric structure.