Organofluorine Compounds and Fluorinating Agents; 18:1 Trifluoromethylzinc Bromide as a Reagent for the Preparation of Glycosyl Fluorides

All articles of this category 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 2 β and 4 β . The other bromides 5, 7 and 9 formed mixtures of anomeric fluorides ( 6 α / 6 β , 8 α / 8 β , 10 α / 10 β ). Similarly, 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 2 α / 2 β , 6 α / 6 β , 14 α / 14 β , 16 α / 16 β , and 18 α / 18 β were obtained. pyranoses - glycosyl bromides - substitution - glycosyl fluorides