436
3
Chemical Glycosylation Reactions
⊡ Scheme 8
⊡ Scheme 9
⊡ Scheme 10
⊡ Table 6
Preparation of glycosyl fluoride from glycosyl bromide
Reagent
Ref.
AgF
[45,46]
ZnF 2 -2,2 -bipyridine [47]
CF 3 ZnBr·2MeCN
[42]
syl fluorides in high yields. Compared to the unprotected analogue, the 1-O-acetylated derivatives preferentially underwent fluorination by this reagent ( > Scheme 10) [40]. Furthermore,
it was found that the reaction of penta-O-acetyl-β-D-glucopyranose, which had a participating
acetoxy group at the C-2 position, gave a mixture of the α-and β-fluorides in which the latter
predominated.
The preparation of glycosyl fluorides from other glycosyl halides is summarized in > Table 6.
Glycosyl bromides were effectively reacted with metal fluorides such as AgF ( > Scheme 11)
3
Chemical Glycosylation Reactions
⊡ Scheme 8
⊡ Scheme 9
⊡ Scheme 10
⊡ Table 6
Preparation of glycosyl fluoride from glycosyl bromide
Reagent
Ref.
AgF
[45,46]
ZnF 2 -2,2 -bipyridine [47]
CF 3 ZnBr·2MeCN
[42]
syl fluorides in high yields. Compared to the unprotected analogue, the 1-O-acetylated derivatives preferentially underwent fluorination by this reagent ( > Scheme 10) [40]. Furthermore,
it was found that the reaction of penta-O-acetyl-β-D-glucopyranose, which had a participating
acetoxy group at the C-2 position, gave a mixture of the α-and β-fluorides in which the latter
predominated.
The preparation of glycosyl fluorides from other glycosyl halides is summarized in > Table 6.
Glycosyl bromides were effectively reacted with metal fluorides such as AgF ( > Scheme 11)