Methyl D-galactofuranoside (l), methyl D-glucofuranoside (3), 3-0-substituted 1,2 : 5,6-di-O-isopropylidene-c~-~-glucofuranoses (5a-g), 1,2-O-isopropylidene-3,5,6-tri-O-methyl-c~-~-glucofuranose (7) as well as the trans-decalin analog 1,2-O-ethanediyl-3,4,6-tri-O-methyl-~-~-glucopyranose (13) are selectively transformed with deacetalisation into the corresponding acylated glycosyl fluorides 2, 4, 6a-g, 8, and 14 by HF/nitromethane/carboxylic acid anhydride. The reaction is realized without change of the ring size if the three-component agent system is mixed some time before the carbohydrate is added.
3,5,6-Tri-O-methyl-2-O-pivaloyl-~-glucofuranosyl fluoride (8)and 2-O-(2-acetoxyethyl)-3,4,6-tri-O-methyl-c~-~-glucosyl fluoride (14) are used as starting materials to synthesize three isomeric, chiral crown ethers, the bis-~-~-glucofuranosido-12crown-4 derivative 12 and both stereoisomeric bis-D-glucopyranosido-12-crown-4 derivatives 20 and 21.