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.