Dániel Eszenyi

Large-scale synthesis of 6-deoxy-6-sulfonatomethyl glycosides and their application for novel synthesis of a heparinoid pentasaccharide trisulfonic acid of anticoagulant activity

Multigram-scale syntheses of three 6-deoxy-6-sulfonatomethyl α-glucosides were accomplished via reactions of the corresponding primary triflate derivatives with the lithiated ethyl methanesulfonate. Chemoselective glycosylation reactions of different 6-C-sulfonatomethyl glucoside donors were studied. The sulfonic acid-containing building blocks were utilised in a novel [2+3] block synthesis of a trisulfonic acid isoster of the anticoagulant pentasaccharide idraparinux.

Preparation of synthetic oligosaccharide-conjugates of poly-β- (1→6)-N-acetyl glucosamine

Staphylococcus aureus and Staphylococcus epidermidis are prominent bacterial pathogens of nosocomial infections. Both microorganisms colonize medical devices by forming adherent biofilms. Poly-β-D-(1→6)-N-acetyl-glucosamine (PNAG) is a surface polysaccharide antigen which was found on both S. aureus and S. epidermidis. Animal studies have proved that PNAG can elicit antibodies which protect against staphylococcal infections. We have presented the synthesis of di-, tetra- and hexasaccharide fragments of PNAG with formyl-heptyl aglycone and their attachment to bovine serum albumin (BSA) by reductive amination.

Promotion of a Reaction by Cooling: Stereoselective 1,2‐cis‐α‐Thioglycoconjugation by Thiol‐Ene Coupling at −80 °C

The photoinitiated thiol-ene coupling reactions of 2-substituted glycals were studied as a generally applicable strategy for stereoselective 1,2-cis-α-thioconjugation. Although all glycals reacted with full α-selectivity, the efficacy of the reactions varied in a broad range depending on their configuration and glycals bearing axial acetoxy substituents reacted with very low efficacy at room temperature. The study revealed that the reaction progress could be promoted by cooling and inhibited by heating. At -80 °C, the equilibrium of the rapidly reversible addition of the thiyl radical to alkenes is shifted almost completely toward products, leading to efficient addition reactions. By exploiting this unique temperature effect a series of α-thio-l-fucosides, -d-galactosides, and d-GlcNAc derivatives were prepared with high efficacy and complete stereoselectivity.