Reactivity and Selectivity in Glycosylation Reactions
The glycosylation reaction is a pivotal reaction in creating new and complex oligosaccharides.
- Vorm, S. van der
- 11 October 2018
- Thesis in Leiden Repository
The glycosylation reaction is a pivotal reaction in creating new and complex oligosaccharides. These biologically relevant compounds must be obtained in enough quantity and in pure, well-defined form. Organic synthesis can provide these compounds, but efficient methods regarding their selective synthesis are often absent. Every saccharide building block is coupled to another in a glycosylation reaction, which must be both regioselective and stereoselective. For the stereoselectivity of this reaction common protocols are not generally applicable. This thesis investigates the stereoselectivity of the glycosylation reaction from the standpoint of the sugar acceptor, rather than from the sugar donor which has been the focal point for many decades. The results obtained showed that a scale of selectivities can be obtained by changing the reactivity of the acceptor. The trends within the acceptor reactivity are valid for all donors studied, but some donors are more susceptible than others to changes in acceptor reactivity. In the second part of this thesis the spatial identity of intermediates in the glycosylation reaction are investigated. Experimental and computational techniques combined resulted in an effective model to understand the glycosylation reaction on the SN1-side of the reaction spectrum when different functional groups are located on the carbohydrate donor.