alpha-D-Mannopyranosyl bromide, 2,3,4,6-tetraacetate → 2,3,4,6-Tetra-O-acetyl-alpha-D-mannopyranosyl fluoride

Participants

Reaction Steps

8.7 g (21.2 mmol) of 2,3,4,6-tetra-O-acetyl-α-D-mannopyranosyl bromide were dissolved in 30 ml of anhydrous acetonitrile and the solution was heated under reflux with 5.0 g (64 mmol) of potassium hydrogen difluoride. After 3 hours, the starting material was no longer detectable (TLC: methylene chloride/ether, 9:1). The solution was filtered and concentrated and the crude product was recrystallized from ether. Yield 5.74 g (77%), melting point 65°-67° C., [α]D20 =+21.2 (c=1.07 in chloroform) [A. Bertho, loc. cit.: melting point 68°-69° C., [α]DS20 =+21.5 (chloroform)]. 1H NMR (CDCl3): δ=5.58 (dd, 1-H), J1,2 =1.9, J1,F =48.4 Hz; [L. D. Hall et al., Can. J. Chem. 47, 1 (1969): δ=5.57 (dd, 1-H), J1.2 =1.7, J1,F =48.6 Hz].

Provenance & Evidence