Modern Synthetic Procedures for the Fluorination of Organic Molecules

Abstract

In view of the number and diversity of publications on organofluorine chemistry in the recent years, it is evident that, since presenting the first series «Fluorierungsmethoden in der Organischen Chemie», fluorination reactions remain of general interest. The objectives of research in the various studies are quite similar. These include selective fluorination of biologically active substances such as steroids, nucleobases, pharmaceuticals, carbohydrates like sugars and glycosides; systematic studies for developing universally applicable fluorinating agents or improving reaction conditions; optimization of yield and selectivity as well as suppression of side reactions. – Elemental fluorine has become increasingly important as a selective fluorinating agent. The critical factor for successful reactions is to suppress radical fluorination which almost exclusively results in perfluorination, fragmentation or oxidative halogenation of heteroatoms or of alkene- and alkyne-bonds. Radical suppression is achieved by diluting fluorine with an inert gas in the presence of a radical-abstractor and in a suitable solvent at low temperature. – Concerning SF₄ and its derivatives, a renaissance has been realized. To date, these compounds are among most important and multifunctional fluorinating agents. New agents with different fluorinating qualities such as CsSO₄F, HOF or OF₂ must be added to the list; however, their range of applicability has not yet been fully explored. In the field of CF₃- and CF₃S-substitution, novel, interesting pathways have been presented, in which the selectivity of new CF₃- and CF₃S-donating agents is outstanding. – As a completement to and continuation of the in 1981 published «Fluorierungsmethoden in der Organischen Chemie», new fluorination methods and new variations of known procedures are reviewed.