Oxygen nucleophiles as reaction partners in photoinduced, copper-catalyzed cross-couplings: O-arylations of phenols at room temperature
Most copper-catalyzed cross-couplings require an elevated reaction temperature. Recently, a photoinduced variant has been developed that enables C–X bond-forming reactions of certain nitrogen and sulfur nucleophiles to proceed under unusually mild conditions (−40 °C to room temperature). In view of the importance of carbon–oxygen bond construction in organic chemistry, the expansion of this photochemical approach to oxygen nucleophiles is an important objective. In this report, we establish that, in the presence of light and an inexpensive copper pre-catalyst (CuI), a wide array of phenols and aryl iodides can be coupled to generate diaryl ethers under mild conditions (room temperature) in the presence of a variety of functional groups. Our studies indicate that a Cu(I)–phenoxide complex is a viable intermediate in photoinduced C–O bond-formation.