Synthesis of a conjugable hexasaccharide corresponding to the capsular polysaccharide of Campylobacter jejuni strain BH0142

The first assembly of a conjugation-ready hexasaccharide from the capsular glycan of C.jejuni.strain BH0142 has been accomplished.The synthesis features the efficient preparation of 6-deoxy-D-idoheptopyranosyl fluoride donors proceeding from allylα-D-C-glucopyranoside by a C1-to-C5 switch strategy with radical dehydroxymethylative fluorination as a key step,stereocontrolled construction of 1,2-trans-α-D-ido-heptopyranosidic bonds and of 1,2-cis-α-D-galactopyranosidic linkages.The obtained target oligosaccharide sets a solid foundation for making structurally-defined multivalent glycoconjugate vaccine candidates against C.jejuni.infections.

Assembly of a Library of Trisaccharides as Mimics of Sialyl Lewis Xvia Random Combination Strategy

A small library containing six positional isomers of fucosyl on the modified lactoside backbone as mimics of the Sialyl Lewis X was synthesized via random combinatorial glycosylation, which was charactered by ESI-MS and HPLC.

Donor Preactivation-Based Glycosylation:An Efficient Strategy for Glycan Synthesis

Carbohydrates have gained a lot of appreciation in the past few decades due to their important roles in numerous biological events.Acquiring a structurally well-defined carbohydrate compound is essential for the understanding of its functions.Although some innovative methods have been developed for the synthesis of complex oligosaccharides,glycan synthesis is in general still a time-consuming and difficult work.Herein,we will introduce the preactivation-based glycosylation strategy,which is an efficient protocol independent of the reactivity of glycosyl donor.This review will focus on summarizing the versatile applications of preactivation strategy in stereoselective glycosylation and one-pot assembly of biologically important oligosaccharides and even polysaccharides。

Capture-Release Strategy Facilitates Rapid Enzymatic Assembly of Oligosaccharides

A convenient and highly efficient strategy was developed for the simplification of enzymatic synthesis and purification of oligosaccharides.Glycosyl acceptors terminated with a thiol tag were extended by enzymatic modular assembly(EMA)in the aqueous phase,and the desired products were captured during solid-phase workup(SPW)using commercially available thiopropyl Sepharose 6B resin through a reversible disulfide linkage.Finally,the products were released from solid-phase resin in the presence of dithio-threitol(DTT)as reducing agent and the resin could be recovered and reused.This strategy overcomes the uncertain influence of polymer-or ionic-supports commonly used in enzymatic glycosylation,and showed perfect compatibility with all 10 enzyme modules for the rapid assembly of a series of complex oligosaccharides.