New approaches to stereocontrolled glycosylation

Thesis

The conceptually simple process of linking carbohydrate units by glycosylation has proven to be one of the most difficult synthetic processes to control from a stereochemical perspective. In particular it is the stereocontrolled synthesis of 1,2-cis glycosyl linkages (e.g. α-glucosides, β-mannosides) which poses the most difficult challenge. The research presented in this thesis describes new ways in which stereocontrol in glycosylation reactions can be achieved. New methods of neighbouring group participation have been explored, utilising novel protecting groups at the 2-postion of a series of glycosyl donors.

In particular the use of glycosyl donors bearing a (thiophen-2-yl)methyl protecting group at the 2-hydroxyl have shown exceptional α-selectivity especially when used in conjunction with a sterically hindered glycosyl acceptor.

Work within this thesis also describes the first use of chiral Brønsted acid catalysts in the activation of glycosyl donors. It has been clearly demonstrated that not only can such catalysts be used in glycosylation reactions, but also that the chirality of the catalyst can dictate the stereochemical outcome of the reaction. The preliminary studies presented demonstrate that this methodology warrants further investigation.

Authors: Cox, D

• Publication date: 2011
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Neighbouring Group Participation; Carbohydrate Chemistry; Glycosylation; Stereocontrol; Chiral Acid
• Subjects: Organic chemistry