Hydrogen Peroxide‐Initiated Polarity‐Inversion S <i> _N </i> Ar of Halophenols with Carboxylic Acids

Polarity‐inversion S N Ar offers a useful solution to the electronic limitations of classical two‐electron nucleophilic aromatic substitution. Here, we report a hydrogen peroxide‐initiated S N Ar of halophenols with carboxylic acids using commercially available 30% aqueous H 2 O 2 as a simple initiator. Under operationally straightforward conditions, this method converts readily available halophenols into para ‐acyloxy arenes, accommodates a broad range of carboxylic acids, and is readily scalable to gram scale. The electrophile scope, however, shows a clear dependence on ortho substitution adjacent to the phenolic OH group. Overall, the present method provides a practical and complementary H 2 O 2 ‐initiated option for thermally driven carboxylate coupling of halophenols.