Dialkylaminodifluorosulfinium tetrafluoroborate salts: synthesis and applications
The syntheses of dialkylaminodifluorosulfinium tetrafluoroborate salts are described. These reagents, first used for the deoxyfluorination of alcohols, were also shown to fluorinate aldehydes, ketones, carboxylic acids and glycosyl groups. Alternatively, dialkylaminodifluorosulfinium tetrafluoroborate salts were recently shown to act as activating agents for hydroxyl, carbonyl and carboxyl groups in a variety of transformations leading to non-fluorinated products.
With 30 to 40% of agrochemicals and 20 to 25% of pharmaceutical compounds bearing at least one atom of fluorine (1), the development of efficient fluorination methods is a highly active field of research within organic synthesis. Deoxyfluorination represents a valuable strategy to insert fluorine atoms on organic compounds (2). However, deoxyfluorination agents are often hygroscopic, unstable, toxic, hazardous and/or non-selective towards fluorination. Dialkylaminodifluorosulfinium tetrafluoroborate salts (3) were developed as cost effective, safer and more efficient deoxyfluorination reagent when used in conjunction with an appropriate base or fluoride additive (4, 5). Since their first uses, researchers have discovered a number of alternate applications for these reagents, such as cyclodehydration, hydroxyl, carboxyl and glycosyl derivatives activation towards substitution, thus broadening the field of action of these practical and inexpensive salts.
PREPARATION OF DIALKYLAMINODIFLUOROSULFINIUM TETRAFLUOROBORATE SALTS
Markovskii et al. first reported the formation of dialkylaminodifluorosulfinium tetrafluor ...