Heterocyclic Betaines: Pyridinium (Imidazolium) Azolate Inner Salts with Several Interannular Linkages

摘要: Publisher Summary This chapter illustrates an ensemble of highly dipolar heterocyclic compounds within betaines, molecules with a betaine character and their crucial immediate precursors. It is noted that in betaines the positive charge located on pyridinium ring negative azolium ring. Both fundamental practical interests are mainly due to has dominant influence chemistry. classification generation systems, essentially brings into relation aromatic ones. Heterocycles related two simple ways— namely, by replacing sp 2 carbon atom pyridine-like nitrogen phenanthrene leads phenanthridine, or adjacent carbons atoms C (sp )–C ) bond heteroatom. The concept aromaticity for been subject extensive research. also observed if reference unusual structures, such as sesquifulvalene its vinylogues, opportunities developing new can be great.