606
3
Chemical Glycosylation Reactions
⊡ Scheme 35
Retrosynthesis of nodulation factor NodRf-III (C18:1) (MeFuc)
⊡ Scheme 36
Synthesis of nodulation factor NodRf-III (C18:1) (MeFuc)
The retrosynthetic analysis dictated a heptasaccharide 251, with all free hydroxyls in the final
product benzylated, and the three sites of phosphorylation all differentially protected, so that
all three can be manipulated separately for maximal flexibility. The free amine of glucosamine
is protected as an azide, which can be taken through multiple transformations and will only
be unmasked at the end of the synthesis ( > Scheme 37). The heptasaccharide is in turn put
3
Chemical Glycosylation Reactions
⊡ Scheme 35
Retrosynthesis of nodulation factor NodRf-III (C18:1) (MeFuc)
⊡ Scheme 36
Synthesis of nodulation factor NodRf-III (C18:1) (MeFuc)
The retrosynthetic analysis dictated a heptasaccharide 251, with all free hydroxyls in the final
product benzylated, and the three sites of phosphorylation all differentially protected, so that
all three can be manipulated separately for maximal flexibility. The free amine of glucosamine
is protected as an azide, which can be taken through multiple transformations and will only
be unmasked at the end of the synthesis ( > Scheme 37). The heptasaccharide is in turn put