Cap and Capture−Release Techniques Applied to Solid-Phase Synthesis of Oligosaccharides

Synthesis of oligosaccharides to identify an immunologically active epitope against Candida auris infection

Candida auris (C. auris) is an emerging multidrug-resistant fungal pathogen that represents a significant public health challenge as it can spread rapidly and result in high mortality rates. The mannans on the C. auris cell surface are potent immunogens and attractive targets for developing a glycoconjugate vaccine. We synthesized the oligosaccharides resembling cell surface mannans of C. auris and printed them onto microarray slides that were used to screen plasma from mice infected with C. auris. IgM antibodies in mouse plasma recognize the β-1,2 linkage present in C. auris surface mannans. Disaccharide 19 emerged from glycan array screening as a lead for developing a vaccine against C. auris, as the majority of patient plasma samples showed antibodies against this glycan. The synthetic oligosaccharides can be used for the early detection of C. auris infections.

One-Pot Synthesis of Glycosyl Chlorides from Thioglycosides Mediated by Bromodiethylsulfonium Salt as A Mild Oxidant

Conventional synthesis of glycosyl chlorides from thioglycosides relies on the two sequential oxidation and chlorination. A one-pot synthesis of glycosyl chlorides is warranted as an alternative method. Herein, we report the one-pot synthesis of glycosyl chlorides from thioglycoside precursors. The transformation was mediated at low temperature by bromodiethylsulfonium bromopentachloroantimonate (BDSB) as a mild oxidant and n-Bu4NCl as an additive. The armed thioglycosides afforded the corresponding α-glycosyl chlorides in moderate to good yields under the optimized conditions. Low conversions and yields were obtained when the less reactive disarmed thioglycosides were used. Unexpectedly, BDSB-mediated oxidation of thioglycosides without the addition of n-Bu4NCl also afforded the α-glycosyl chlorides in moderate yields. We suggest a mechanism involving the transfer of chloride ions from the non-nucleophilic bromopentachloroantimonate (SbCl5Br) anion to the oxocarbenium ion.

Chemical O-Glycosylations: An Overview

The development of glycobiology relies on the sources of particular oligosaccharides in their purest forms. As the isolation of the oligosaccharide structures from natural sources is not a reliable option for providing samples with homogeneity, chemical means become pertinent. The growing demand for diverse oligosaccharide structures has prompted the advancement of chemical strategies to stitch sugar molecules with precise stereo- and regioselectivity through the formation of glycosidic bonds. This Review will focus on the key developments towards chemical O-glycosylations in the current century. Synthesis of novel glycosyl donors and acceptors and their unique activation for successful glycosylation are discussed. This Review concludes with a summary of recent developments and comments on future prospects.

Convergent synthesis of oligosaccharides on the gram-scale using cetyl thioglycoside based on a hydrophobically assisted switching phase method

A hydrophobically assisted switching phase (HASP) method is an efficient strategy for the synthesis of carrier-loaded oligosaccharides.

Efficient assembly of oligomannosides using the hydrophobically assisted switching phase method

The hydrophobically assisted switching phase (HASP) method was applied in the assembly of oligomannosides. A new mannosyl donor with high reactivity was selected after a series of optimization studies, which was suitable for the synthesis of oligomannosides via the HASP method. The practicability of the HASP method towards the synthesis of branched oligosaccharides was explored and two branched penta-mannosides were assembled efficiently.