Preparation of acetylated 1-fluoroglycopyranosyl cyanides

Article abstract of DOI:10.1016/S0040-4020(98)00813-8

Reactions of acetylated 1-bromo-1-deoxy-glycopyranosyl cyanides of β- D-galacto (2) and α-D-arabino (12) configurations with silver fluoride in acetonitrile at room temperature gave the corresponding 1-deoxy-1- fluoroglycopyranosyl cyanides (5 and 13, respectively) with inversion of the anomeric centre. Under similar conditions the β-D-gluco (1) and β-D-xylo (3) compounds resulted in the corresponding inverted 1-fluoroglycosyl cyanides (4 and 6, respectively) together with significant amounts of 1- cyano-2-hydroxy-glycals (9 and 10, respectively). Silver tetrafluoroborate in toluene at room temperature convened 2 and 3 into the 1-fluoroglycosyl cyanides (7 and 8, respectively) of retained anomeric configuration. 1- Chloro-1-deoxy-α-D-galactopyranosyl cyanide (11) also gave 7 with silver fluoride in acetonitrile at reflux temperature. Conformational equilibria of the 1-deoxy-1-fluoro-pentopyranosyl cyanides 6, 8, and 13 reflect counteraction of the anomeric effects exerted by the fluorine and the cyano group. 1-Deoxy-1-fluoro-α-D-galactopyranosyl cyanide proved to be a weak competitive inhibitor of E. coli β-D-galactosidase (K(i) = 2 mM).