Synthesis of glycosyl fluorides from thio-, seleno-, and telluroglycosides and glycosyl sulfoxides using aminodifluorosulfinium tetrafluoroborates

Monofluorination of Organic Compounds: 10 Years of Innovation

“…Williams and co-workers reported, in 2012, the desulfurization-fluorination of thioglycosides mediated by XtalFluor-E (Scheme ) . These conditions formed the desired glycosyl fluorides in moderate to excellent yields and were also applied to telluro- and selenoglycosides as well as glycosyl sulfoxides.…”

Beyond the Balz–Schiemann Reaction: The Utility of Tetrafluoroborates and Boron Trifluoride as Nucleophilic Fluoride Sources

“…In a recent development, Williams and co-workers have demonstrated that commercially available aminodifluorosulfinium tetrafluoroborate reagents, XtalFluor-E and XtalFluor-M, are also able to effect the conversion of glycosyl sulfides 64 to glycosyl fluorides 65 (eleven examples, 45–94% yield) (Scheme ) . In all cases, the α-anomers of the products were exclusively obtained.…”

Dialkylaminodifluorosulfinium Salts: XtalFluor-E and XtalFluor-M

“…6 Chlorination, bromination and iodination reaction of primary alcohols in good yield has been described using a combination of tetraethylammonium halide and XtalFluor-E. 7 Fuchs and co-workers have recently reported the preparation of a fluorodisaccharide in excellent yield without side products using XtalFluor-E, thus eliminating the need for purification. 9 The effective preparation of glycosyl fluorides from thio-, seleno-, telluro-and glycosyl sulfoxides has been performed in 30 minutes by Williams and co-workers with evidence that fluoride is delivered by the tetrafluoroborate counterion 10 (E) Enantioselective Ring Expansion of Prolinols: Direct ring expansion of N-alkyl prolinols to produce the corresponding 3-azidopiperidines in good and excellent regio-, diastereo-and enantioselectivity was achieved by using XtalFluor-E. Formation of an aziridinium intermediate which reacts with a nucleophile such as tetrabutylammonium azide (Bu 4 NN 3 ) is proposed.…”