General Copper‐Catalyzed Transformations of Functional Groups from Arylboronic Acids in Water

A simple and general copper‐catalyzed method has been developed for transformations of various functional groups (I, N 3 , SO 2 R, OH, NH 2 , and NO 2 ) on aromatic rings from arylboronic acids in water under air. The protocol uses cheap and readily available inorganic salts (KI, NaN 3 , NaSO 2 R, NaOH, NaNO 2 ) and aqueous ammonia as the functional‐group sources, simple Cu 2 O/NH 3 as the catalyst system, environmentally friendly water as the solvent, and oxygen in air as the oxidant. Importantly, the copper catalyst system in water was recyclable. This study should provide a useful strategy for interconversions of the functional groups on aromatic rings.