The Regioselective Functionalization of Pyridine at 2,3,4-positions via Carbene Intermediate

The synthetic and mechanistic aspects of highly energetic pyridine carbenes (PyCs) are discussed for understanding the regio- and stereoselective functionalization of pyridine at rare sites by applying different C-H bond activation methods. Various transition metals and metalloids are used for the generation of corresponding PyCs followed by the formation of substituted pyridines. The functionalization of most focused 2,3,4- positions of pyridine is described with several applications in the synthesis of drugs and natural products, in single-walled carbon nanotubes (SWNTs) and in dye-sensitized solar cells (DSSCs) as the energy storage compounds.