Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides

Article abstract of DOI:10.1002/anie.202106440

Nucleophilic aromatic substitution (S_NAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic S_NAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical S_NAr conditions. Although the mechanism of S_NAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η⁵-cyclohexadienyl complex intermediate with an sp³-hybridized carbon bearing both a nucleophile and a leaving group.