Fluorine Effect In Nucleophilic Fluorination At C4 Of 1,6-Anhydro-2,3-Dideoxy-2,3-Difluoro-Beta-D-Hexopyranose

In this work, we have developed a simple synthetic approach using Et3N.3HF as an alternative to the DAST reagent. We controlled the stereochemistry of the nucleophilic fluorination at C4 of 1,6-anhydro-2,3-dideoxy-2,3-difluoro-4-O-triflate-beta-D-talopyranose using Et3N.3HF or in situ generated Et3N.1HF. The influence of the fluorine atom at C2 on reactivity at C4 could contribute to a new fluorine effect in nucleophilic substitution. Finally, with the continuous objective of synthesizing novel multi-vicinal fluorosugars, we prepared one difluorinated and one trifluorinated alditol analogue.