Conference by Prof Carmen GALAN

 Prof. Carmen GALAN,  School of Chemistry, University of Bristol, UK

O-Glycosylation is a ubiquitous post-translational modification that is highly dynamic and responsive to cellular stimuli through the action of the cycling enzymes. Expression of specific O-glycans is linked to changes in gene expression in, for example, inflammatory bowel disease, cystic fibrosis and several types of cancer.

The stereoselective synthesis of glycosides remains one of the biggest challenges in carbohydrate chemistry. The chemical synthesis of complex carbohydrates generally involves the coupling of a fully protected glycosyl donor bearing a leaving group at its anomeric centre, with a suitably protected glycosyl acceptor (R-OH). In many instances, these reactions lead to a mixture of two stereoisomers.Towards this goal, our group has endeavoured to develop catalytic and stereoselective methods to address this important synthetic challenge. Recent years have seen a steady increase in the application of transition metal catalysis applied to oligosaccharide synthesis, since the reaction conditions are mild and the careful choice of catalyst can offer significant improvements over traditional methods in terms of atom economy, high yields and control of anomeric selectivity.

Herein, we will discuss the application of transition metal catalysis in the stereoselective synthesis of deoxy glycosides, including the a,a-stereoselective synthesis of trehalose derivates and their application as selective probes of bacteria detection.^[4] Moreover, I will also disclose recent development of a rapid bacteria screening strategy based on carbohydrate-functionalized polystyrene microspheres. Using this assay, we identified selective binding of C-2 linked arabinose moieties immobilized on a microbead surface to Staphylococcus aureus, a Gram-positive pathogenic bacterium of which antimicrobial-resistant strains are widespread and problematic.