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Stereo-controllable glycosylation reactions of 2,3-oxazolidinone protected glucosamine thioglycoside donor with different phenol acceptors based on preactivation protocol, are described. It was found that BF3·Et2O worked as α-directing additive, while TTBP acted as β-directing additive. Simply by altering additives, either α-aryl glycosides or β-aryl glycosides were achieved in a stereoselective manner. The additives were also applied to the stereoselective glycosylation reactions of 2,3-oxazolidinone protected galactosamine donor with phenol substrates.

The repeating GalpNAc-alpha-(1--4)-GalpNAc unit is part of a series of essential structures that can be found in many important biomolecules such as the glycoproteins and the O-antigenic polysaccharides of clinically important bacterial strains. In this paper, we describe an exclusive alpha-selective glycosylation reaction, using a 4,6-di-O-tert-butyldimethylsilyl-N-acetyloxazolidinone-protected thioglycoside as the glycosyl donor, under pre-activation conditions, with only half amount of the promoter, providing the product GalpNAc-alpha-(1--4)-GalpNAc in high isolated yield. This reaction can be also applied to increasing the length of the repeating structure, which is of significant use in further synthesis of branched or linear oligosaccharides.

Several N-alkyl and hydroxyethyl-substituted iminosugar derivatives, including L-altro and D-galacto epimers, were synthesized and the effects of these synthetic iminosugars on proliferation of mouse splenocytes were evaluated in the MTT assay. The experimental data demonstrated that the N-alkylated D-galacto iminosugars showed better inhibitory activities than L-altro analogues, which might hold potential as immunosuppressive agents.

Abnormal glycosphingolipids (GSLs) are expressed in many human tumors. These tumor-associated GSLs may have important roles in tumor progression. However, they are hard to be detected because of their low concentration and the limited availability of antibodies and lectins that recognize them. Thus, mass spectrometry is an effective method to analyze GSLs with high sensitivity. Here, we use electrospray ionization-linear ion trap quadrupole mass spectrometry (ESI-LTQ-MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) to determine the structure of a certain GSL in human breast cancer tissue. To obtain the breast cancer-associated GSLs, we applied relative abundance contrast of GSLs and signal-to-noise ratio (SNR) analyses. We also used α1,2 fucosidase and fucosyltransferases as tools in the structural analysis. Based on this analysis, we identified the ion with m/z 1184 molecular ion as fucosyl-lactoceramide (Fuc-LacCer) with a C16 fatty acid ceramide. Quantitative analysis of GSLs revealed both Fuc-LacCer and Globo-H increased in breast cancer tissues. However, these two breast cancer-associated GSLs had different roles. The results of SNR analysis suggested the abnormal Fuc-LacCer is specific to breast cancer. The GSL profiling of breast cancer cells showed fucosyltransferase 1 contributed to the biosynthesis of Globo-H and Fuc-LacCer. In conclusion, MS analysis identified an accumulation of Fuc-LacCer in breast cancer tissue. Our findings provide GSL profiles of human breast cancer and develop an MS method for the study of cancer-associated GSLs.

Thioglycosides are widely used in orthogonal glycosylation, armed-disarmed chemoselective glycosylation, and preactivation-based glycosylation. Nevertheless, aglycon transfer occasionally occurred in the glycosylation process of thioglycosides. This problem was also encountered in preactivation-based reactions, which limited the applications of preactivation-based glycosylation to some extent. To tackle this problem, sterically hindered aglycon ortho-methylphenylthioglycosides were introduced as glycosyl building blocks. These thioglycosides prevented the aglycon transfer and enhanced the efficiency of glycosyl coupling reactions, especially in the reactions of disarmed donors with armed acceptors. Moreover, these thioglycosides were employed in preactivation-based one-pot oligosaccharide assembly.