Glycosylation on Polymer Supports

Abstract

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.

Modeling the mechanism of glycosylation reactions between ethanol, 1,2-ethanediol and methoxymethanol

“…The glycosylation reaction can be defined as the chemical condensation process in which one reactant with a suitable leaving group and an electrophilic carbon atom, the glycosyl donor, reacts with the other reactant with an unprotected nucleophilic group, the glycosyl acceptor, that attacks the electrophilic centre, to form the C-X glycosidic bond. [1][2][3] Despite the fundamental role of this reaction, the details of the glycosylation process remain relatively poorly understood. 4,5 On the one hand, the S N 1 mechanism was proposed by Rhind-Tutt and Vernon 6 and subsequently refined by Lucas and Schuerch 7 and by Lemieux and co-workers 8 based on the general solvolysis reaction.…”

2,2,6,6-Tetramethylpiperidin-1-yloxycarbonyl: A Protecting Group for Primary, Secondary, and Heterocyclic Amines

“…Synthetic efficiency in routes toward complex target molecules, including natural products, strives to minimize the use of protecting groups; however, basic amines are frequently incompatible with transition metal catalysis and oxidative conditions and often require protection during these transformations. − Furthermore, protecting groups continue to play a critical role in peptide synthesis and carbohydrate chemistry . Therefore, the development of new protecting groups remains an important goal in organic and biological chemistry.…”

“…1−3 Furthermore, protecting groups continue to play a critical role in peptide synthesis 4 and carbohydrate chemistry. 5 Therefore, the development of new protecting groups remains an important goal in organic and biological chemistry. Orthogonal protecting groups that allow for selective manipulations in molecules with multiple functionalities are particularly useful in this context.…”