Photoredox-Catalyzed Radical-Radical Cross-Coupling of α-Ketoesters with Ethers: Access to Sterically Hindered α-Hydroxy Esters

We describe a photoredox catalysis method for synthesizing sterically hindered alpha-hydroxy esters from alpha-ketoesters and ethers through a radical-radical cross-coupling reaction. This approach utilizes commercially available Ir[dF(CF3)ppy](2)(dtbbpy)PF6 as a photocatalyst and inexpensive and readily available (Bu4NBr)-Bu-n as a hydrogen atom transfer catalyst. Unactivated tetrahydrofuran and other ethers effectively react with various alpha-ketoesters to yield the desired products. The efficiency of this reaction is highlighted by its broad substrate scope, good functional group tolerance, and mild reaction conditions.