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The glycan portion of ganglioside HLG-2, which was identified in the extracts of the sea cucumber Holothuria leucospilota , was synthesized in a highly efficient and stereoselective manner. The unusual sequence of the trisaccharide moiety, α-N-glycolylsialyl-(2,4)-α-N-acetylsialyl-(2,6)-glucoside, was assembled by stereoselective coupling of a 5-N,4-O-carbonyl-protected sialyl phosphate donor, a N-2,2,2-trichloroethoxycarbonyl (Troc)-protected sialyl acceptor, and a (trimethylsilyl)ethyl-β-glucosyl acceptor in high yield. The synthesis featured the high-yielding construction of two α-sialyl linkages.

The abnormal glycans expressing on the surface of tumor cells are good targets to develop carbohydrate-based anti-cancer vaccines. However, one of the major problems is that carbohydrate antigens possess weak immunogenicity. This review summarizes the recent efforts to overcome this problem: glycoconjugates produced by coupling the carbohydrate antigens and proper carrier proteins improve their immunogenicity, many glycoconjugates have entered clinical trials; the vaccines become chemically well-defined when coupling the carbohydrate antigens with a T-cell peptide epitope and an immunostimulant to form fully synthetic multi-component glycoconjugate vaccines; the modification of carbohydrate antigens in combination with the technology of metabolic oligosaccharide engineering of tumor cells induces a strong immune response; and the fact that the antibodies elicited against the unnatural carbohydrate antigens can recognize the native carbohydrate antigens on tumor cells provides a new promising strategy for the development of anti-cancer vaccines.

In this paper, a convenient approach to the synthesis of the repeating α-(1→4)-linked N-acetyl galactosaminuronic acid units from the capsular polysaccharide of Salmonella typhi is reported. The exclusively α-stereoselective glycosylation reactions were achieved by using oxazolidinone-protected glycosides as building blocks based on a pre-activation protocol. Di-, tri-, and tetrasaccharides were prepared by this short and efficient approach in high yields. The enzyme-linked immunosorbent assay experiments show that our synthetic tri- and tetrasaccharide had much higher antigenic activities than previously reported ones in the inhibition of antibody binding by the native polysaccharide. The results demonstrate that the antigenic activities of saccharides can be strengthened greatly by increasing the number of acetyl groups present., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

O,O-Dimethylthiophosphonosulfenyl bromide (DMTPSB) in combination with silver triflate provides a powerful thiophilic promoter system. Both "armed" and "disarmed" thioglycoside glycosyl donors can be activated to form glycosidic linkages efficiently by the pre-activation protocol. The usefulness of this new promoter is illustrated by a successful iterative one-pot oligosaccharide assembly.

Through effective construction of a compound library and in situ cell-based screening, several iminosugar derivatives were discovered that show a strong ability to enhance IFN-gamma secretion. In particular, compounds A45 and B8, which exhibit remarkable activity in stimulating IFN-gamma secretion, show good antibacterial activity in vivo and have the potential to be lead compounds for further studies in the search for drugs for the treatment of cancer and microbial infections.

A new efficient pre-activation method for the highly alpha-stereoselective glycosylation of 2-deoxysugars and 2,6-dideoxysugars has been developed using 2-deoxy- and 2,6-dideoxythioglycosides as glycosyl donors. The approach allows a wide range of glycosyl acceptors and donors to be used; the alpha-selectivity is very good to excellent.

Two efficient routes for the rapid assembly of the tumor-associated carbohydrate antigen Globo-H hexasaccharide 2 by a preactivation based iterative one-pot strategy are reported. The first method involves the sequential coupling of four glycosyl building blocks, leading to the desired hexasaccharide in 47% overall yield in one-pot synthesis. Although model studies on constructing the challenging Gal-alpha-(1-4)-Gal linkage in Gb3 trisaccharide yielded the desired alpha linkage almost exclusively, a similar approach to assemble the hexasaccharide led to the formation of a significant amount of beta anomer. As an alternative, the second synthesis utilized three components in one pot with the Gal-alpha-(1-4)-Gal linkage preformed, producing the desired hexasaccharide in a similar overall yield as the four component approach. Both methods demonstrate that oligosaccharides containing alpha and beta linkages within the same molecule can be constructed in one pot via a preactivation based approach with higher glyco-assembly efficiencies than the automated solid-phase synthesis strategy. Furthermore, because glycosylations can be carried out independent of anomeric reactivities of donors, it is not necessary to differentiate anomeric reactivities of building blocks through extensive protective group adjustment for chemoselective glycosylation. This confers great flexibilities in the building block design, allowing matching of the donor with the acceptor, leading to improved overall yield.

Saccharide synthesis is a formidable task for synthetic chemists. Although in recent years many advances have been made in this area, development of more convenient and efficient strategies for oligosaccharide synthesis is still in great demand. This review focuses on one of these new strategies--the one-pot sequential glycosylation approach as a potent tool for oligosaccharide assembly.

A new transformation of 2-azido-1-hydroxy-containing compounds to nitriles with one carbon less than the starting materials by oxidation was reported. The reaction can be performed under mild conditions.

A four-component one-pot sequential synthesis of alpha-Gal pentasaccharide 2 with minimal protecting group manipulations in a very short period of time is described in this paper. [structure: see text]

The reaction of 4, 6-O-benzylidene-d-pyranosides with a stoichiometric amount of TsCl, AcCl, and BzCl in the presence of silver(I) oxide and a catalytic amount of potassium iodide led to monosubstituted derivatives in high regioselectivity and in good yields., (Copyright 2004 American Chemical Society)