Combined Photoredox and Lewis Acid Catalyzed α‑Hydroxyalkylation of Cyclic Ethers with Aromatic Ketones

The photochemically induced coupling of aromatic ketones with cyclic ethers such as tetrahydrofuran, tetrahydropyran, and 1,4-dioxane was studied. Direct photolysis of the substrates with UV-A light centered at 350 nm does not lead to photoinduced hydrogen transfer whereas the addition of a mixture of the Lewis acid catalysts Ti­(OiPr)4 and BF3 enables the formation of the hydroxyalkylation products.