Nucleophilic Aromatic Substitution of Halobenzenes and Phenols with Catalysis by Arenophilic π Acids

ConspectusLewis π acids, particularly high-valent transition metals with vacant orbitals, can coordinate with unsaturated compounds such as alkynes and alkenes by means of π-bonding. The coordination enhances the electrophilicity of the bound compounds, thereby facilitating reactions─such as nucleophilic addition─that take place at the ligated carbon-carbon multiple bonds. This activation phenomenon occurs at the ligand rather than at the metal atom, and it has been extensively utilized in the development of catalytic methods. In addition to alkynes and alkenes, aromatic compounds featuring a phenyl ring can be activated by an electrophilic transition-metal unit (e.g., Cr(CO)