Glycosyl Halides
3.1
435
⊡ Scheme 5
⊡ Scheme 6
⊡ Scheme 7
Furthermore, the anomeric hydroxyl group of various furanose and pyranose hemiacetals can be replaced by a fluorine under neutral conditions using an α-fluoroenamine
( > Scheme 8) [43].
Glycosyl fluorides can also be obtained by the modified Mitsunobu reaction using diethyl
azodicarboxylate (DEAD)-PPh 3 -Et 3 O + BF 4
− ( > Scheme 9) [44]. By this method, the acid
sensitive isopropylidene-protected mannofuranosyl fluoride was prepared in moderate yield.
Alternatively, 1-O-acylated sugars can be easily transformed into the corresponding glycosyl
fluorides. Thus, treatment of 1-O-acetylated sugars with HF/Py gave the corresponding glyco-
3.1
435
⊡ Scheme 5
⊡ Scheme 6
⊡ Scheme 7
Furthermore, the anomeric hydroxyl group of various furanose and pyranose hemiacetals can be replaced by a fluorine under neutral conditions using an α-fluoroenamine
( > Scheme 8) [43].
Glycosyl fluorides can also be obtained by the modified Mitsunobu reaction using diethyl
azodicarboxylate (DEAD)-PPh 3 -Et 3 O + BF 4
− ( > Scheme 9) [44]. By this method, the acid
sensitive isopropylidene-protected mannofuranosyl fluoride was prepared in moderate yield.
Alternatively, 1-O-acylated sugars can be easily transformed into the corresponding glycosyl
fluorides. Thus, treatment of 1-O-acetylated sugars with HF/Py gave the corresponding glyco-