Photoinduced Miyaura Borylation by a Rare‐Earth‐Metal Photoreductant: The Hexachlorocerate(III) Anion

The first photoinduced carbon(sp²)–heteroatom bond forming reaction by a rare‐earth‐metal photoreductant, a Miyaura borylation, has been achieved. This simple, scalable, and novel borylation method that makes use of the hexachlorocerate(III) anion ([Ce^IIICl₆]^3?, derived from CeCl₃) has a broad substrate scope and functional‐group tolerance and can be conducted at room temperature. Combined with Suzuki–Miyaura cross‐coupling, the method is applicable to the synthesis of various biaryl products, including through the use of aryl chloride substrates.