Oligosaccharide synthesis has gained major attention in the last two decades particularly in the total synthesis of biologically interesting molecules. Carbohydrates contain many stereocenters and are often branched oligomers. The preparation of these complex methods is time consuming and mostly carried out by specialized laboratories. The synthesis of oligosaccharides is challenging because every glycosylation creates a new stereogenic center. Each carbohydrate unit has up to four sites for chain elongation, which exhibit similar reactivity. The strategic choice of protection for the hydroxyl and amino groups is essential
The use of polymeric support can simplify the synthesis. Glycosylation efficiency can be increased using one coupling partner (either the glycoside nucleophile or glycoslyating agent) or other reagent in excess. Use of polymeric supports results in shortened process times since intermediate purification steps are not required. This chapter deals with the choice of carbohydrate monomers or dimers including the protecting groups and an anomeric leaving group, the choice of polymer support, and the selection of a proper linker resistant to all relevant reaction conditions. The choice of carbohydrate building blocks requires an appropriate protecting group strategy. It is important to consider whether the carbohydrate is connected to the support via the anomeric position or another hydroxyl group.