Room‐Temperature Copper‐Catalyzed Etherification of Aryl Bromides

We disclose the development of a Cu‐catalyzed C−O coupling method utilizing a new N 1 , N 2 ‐diarylbenzene‐1,2‐diamine ligand, L8 . Under optimized reaction conditions, structurally diverse aryl and heteroaryl bromides underwent efficient coupling with a variety of alcohols at room temperature using an L8 ‐based catalyst. Notably, the L8 ‐derived catalyst exhibited enhanced activity when compared to the L4 ‐based system previously disclosed for C−N coupling, namely the ability to functionalize aryl bromides containing acidic functional groups. Mechanistic studies demonstrate that C−O coupling utilizing L8 ⋅ Cu involves rate‐limiting alkoxide transmetallation, resulting in a mechanism of C−O bond formation that is distinct from previously described Pd‐, Cu‐, or Ni‐based systems. This lower energy pathway leads to rapid C−O bond formation; a 7‐fold increase relative to what is seen with other ligands. The results presented in this report overcome limitations in previously described C−O coupling methods and introduce a new ligand that we anticipate may be useful in other Cu‐catalyzed C‐heteroatom bond‐forming reactions.