Pyridinium Ylids in Heterocyclic Synthesis

Pyridinium ylids are versatile tools in organic synthesis. The stability of pyridinium ylids and their generation is commented. This review gives an overview of the possible modes through which pyridinium ylids can react. It is demonstrated that pyridinium ylids are suitable building blocks for the synthesis of indolizines, cyclopropanes, 2,3-dihydrofurans, 2(1H)-pyridin(ethio)ones, mono- & oligopyridines, pyranonaphthoquinones, nitrones and azepines. Keywords: Pyridinium ylid, indolizines, nitrones, pyranonaphthoquinones, pyridines, epoxidation, aziridination, cyclopropanation, olefination, Ortoleva-King Reaction, α-halomethylketones, Photochemical Reaction of α-diazoketones, nitrosoarenes, ketocarbene, oxirene, solvatochromatism