Electrophilic Fluorination with Elemental Fluorine and Reagents Derived from it
Abstract:Elemental fluorine is a highly reactive reagent which could destroy almost any organic compound or perfluorinate it under controlled conditions. However, under the right set of conditions, it may act as an electrophile and as such, it can be a powerful electrophile indeed. This chapter describes some regio- and stereospecific electrophilic fluorination at saturated tertiary sp3 centers, which are usually very unreactive and cannot participate in specific organic reactions. It was concluded that the higher the hybridization on p of these centers, the better is the outcome of the reaction. In many cases, the substitution of such tertiary hydrogen takes place in yields of 70% and more. Such fluorinations, which were carried out on a wide variety of organic compounds, provide an excellent opportunity for dehydrofluorination reactions to form double bonds and hence are considered to enable functionalization of "impossible sites" in organic molecules. Elemental fluorine was also used for fluorination of double bonds, in a syn mode, replacing the old and inefficient method of reacting olefins with Pb(OAc)4 and HF. Acetyl hypofluorite is easily and readily made from sodium acetate and F2. It proved to be a very useful reagent for fluorination of activated aromatic compounds, for addition across double bonds, in order to synthesize biologically important fluorine containing derivatives, for constructing α- fluoro carbonyl and ether derivatives and for use in Positron Emitting Tomography (PET).
Document Type: Research Article
Affiliations: School of Chemistry, Tel-Aviv University, Tel-Aviv 69978, Israel.
Publication date: January 1, 2006