Organofluorine compounds and fluorinating agents; 18. Trifluoromethylzinc bromide as a reagent for the preparation of glycosyl fluorides

Article abstract of DOI:10.1055/s-1997-3181

Trifluoromethylzinc bromide was used to prepare the corresponding glycosyl fluorides from the peracetylated α-pyranosyl bromides of D-glucose 1, D-galactose 3, D-mannose 5, D-lyxose 7, and L-rhamnose 9, respectively, in good yields. D-Glucopyranosyl bromide 1 and the D-galactopyranosyl bromide 3, exclusively delivered the corresponding β-D-glycosyl fluorides 2β and 4β. The other bromides 5, 7 and 9 formed mixtures of anomeric fluorides (6α/6β, 8α/8β, 10α/10β). Similarily, the anomeric OH-groups of the D-glycopyranoses 11, 12, 13, 15, 17 could be substituted by fluoride using trifluoromethylzinc bromide/titanium tetrafluoride. In all cases mixtures of anomeric fluorides 2α/2β, 6α/6β, 14α/14β, 16α/16β, and 18α/18β were obtained.