Selective Functionalization of Pyridines via Heterocyclic Phosphonium Salts

Methods that directly functionalize pyridines are in high demand due to their presence in pharmaceuticals, agrochemicals, and materials. A reaction that selectively transforms the 4-position C–H bonds in pyridines into C–PPh₃⁺ groups that are subsequently converted into heteroaryl ethers is presented. The two step sequence is effective on complex pyridines, pharmaceutical molecules, and other classes of heterocycles. Initial studies show that C–C, C–N, and C–S bond formations are also amenable.