Development of New Fluorination Reaction Using Amine-nHF Complexes as Fluorine Source

Recently, Et3N-nHF complexes have been used for a variety of fluorination reactions instead of hazardous anhydrous HF. This review summarizes the recent progress in the fluorination reaction using Et3N-nHF complexes except Et3N-3HF. Et3N-HF and Et3N-2 HF have been used as nucleophilic fluorinating reagents in the SN2 type ring opening of terminal oxiranes and substitution with alkyl halides. On the other hand, Et3N-5 HF and Et3N-6 HF complexes, which are slightly more acidic than Et3N-3HF, have been used as 1) an electrolyte in electrochemical fluorination reactions 2) a hydrofluorination reagent of alkenes and alkenals and 3) a co-reagent of iodotoluene difluoride in the oxidative fluorination of β-dicarbonyl compounds, alkenes, and alkynes.