Chemistry Reference
In-Depth Information
3.1
Synthesis of Oligosaccharides: Strategies
If larger structures than a disaccharide are to be constructed a strategy for the
synthesis has to be selected in a process that is often referred to as a retrosynthesis.
Starting from the target structure possible disconnection points and building
blocks are identifi ed, and the sequence in which they are to be produced and linked
is decided. Rarely, the original retrosynthetic pathway will be the one used in the
end, but an initial plan and strategy are still necessary. Retrosynthesis of oligosac-
charides is less complex than of most other natural products, mainly since the
disconnection points and many of the building blocks are already given, being the
glycosidic linkages and the monosaccharides, respectively. So for oligosaccharides
the major question will most often be 'In which sequence should the glycosidic
linkages be made?'. Two different main strategies can be identifi ed:
(i) A linear synthesis starting from the reducing end and adding one monosac-
charide at a time to fi nally get to the target structures.
(ii) A block (or convergent) synthesis where larger building blocks are fi rst created
and then linked together to give the target structures (Figure 3.1 ).
Figure 3.1
Schematic block synthesis of a dodecasaccharide containing three identical trisaccharide motifs.
