Expeditious Synthesis of Bacterial Glycoconjugates

Bacterial glycoconjugates are comprised of rare D and L deoxy amino sugars, which are not present on the human cell surface.[1] This peculiar structural difference allows discrimination between the pathogen and the host cell and offers avenues for target-specific drug discovery and carbohydrate-based vaccine development.[2]  However, they cannot be isolated with sufficient purity in acceptable amounts, and therefore chemical synthesis is a crucial step toward the development of these products.  We recently established short and convenient methodologies for the synthesis of orthogonally protected bacterial D and L-deoxy amino hexopyranoside  and glycosamine building blocks starting from cheaply available D-mannose and L-rhamnose.[3-5]  The one-pot protocols rely on highly regioselective nucleophilic displacements of triflates. These procedures have been applied to the synthesis of various bacterial glycoconjugates.[3-10] (Figure 1) as well as metabolic oligosaccharide engineering for selective detection of bacteria.[8]