Copper-MediatedPhosphoniumation of Aryl/Vinyl BoronicAcids

Following the successful construction of nitrilium/pyridinium and sulfonium salts, the Chan–Lam coupling has been significantly advanced with the first demonstration of quaternary phosphonium salt synthesis. We present a method employing copper(II) acetate in trifluoroethanol to efficiently produce a range of aryl and vinyl phosphonium salts from boronic acids, including those derived from complex natural products, thus overcoming phosphine oxidation issues and expanding the scope to functionalized phosphorus.