Synthesis of unsymmetrical biaryl ethers through nickel-promoted coupling of polyfluoroarenes with arylboronic acids and oxygen.

Polyfluoro-substituted unsymmetrical biaryl ethers were synthesized via a novel Ni-catalyzed cross-coupling reaction of polyfluoroarenes with arylboronic acids and oxygen. The polyfluorinated arenes presumably captured the phenoxide intermediate efficiently, which made the oxygen-insertion proceed smoothly via the S(N)Ar protocol. The (18)O labeling experiment demonstrated that the oxygen introduced into unsymmetrical diaryl ether originated from very trace amounts of oxygen in the reaction system. A plausible mechanism was also suggested.