Fluoroheterocycle formation using fluoroalkynes and their synthetic equivalents

The importance of fluorinated heterocyclic compounds has led to the development of new methods for their preparation. This review describes the assembly of fluorinated heterocycles that uses various cycloadditions of fluoroalkynes or their synthetic equivalents. Some of these synthetic equivalents, such as perfluoroalkenes, have been known for a long time, while some of them, such as alkynyl triazenes, fluoronitroalkenes, and difluorovinyl-zinc reagents, gained an attention only recently. The range of reactions includes both classical transformations, such as [3+2]-cycloadditions, and modern transition metal-catalyzed annulations. This allows the preparation of triazoles, indolizines, pyrazoles, pyrroles, and other products possessing fluorine atom at desired positions of the heterocyclic core. Possible side reactions are described. To show the versatility of the approach, some relevant examples for the formation of fluorinated carbocycles are also discussed.