Polyfluoro-pyridyl glycosyl donors


Graham Sandford, graham.sandford@durham.ac.uk and Christopher A. Hargreaves, c.a.hargreaves@durham.ac.uk. Chemistry, University of Durham, South Road, Durham, DH1 3LE, United Kingdom
Carbohydrates have essential functions in a variety of important biological processes, such as metabolism, biosynthesis and as messengers in precise communication events. Indeed, many glyco-conjugates have been synthesised and studied for various therapeutic uses and this potentially very valuable biological activity of new oligosaccharide systems has further stimulated interest in the rapidly developing field of glycobiology. The synthesis of oligosaccharides, by linking a series of mono-saccharide units together via glycoside bonds, remains a key research challenge for the exploitation of glycoconjugates in various biological processes. Of course, many synthetic glycosylation procedures have been described but, as yet, there does not appear to be a general synthetic glycosylation approach that has been universally adopted for all syntheses of oligosaccharides. Future developments in glycosylation methodology require the ready synthesis of families of new glycosyl donors with controllable and variable reactivity in which the electronic demand of the substituents present on the leaving group can ‘tune' the reactivity of each donor using specific activating agents. In this presentation, we describe the synthesis and function of new families of glycosyl donors, in which fluorinated pyridine systems are the leaving groups which may be activated in a controlled ‘tunable' fashion towards nucleophilic attack by appropriate Lewis Acids, depending on the substituents present on the pyridine ring.