Advances in Selective Chemical Syntheses of Complex Oligosaccharides

Abstract

A wide variety of complex oligosaccharides has now been made accessible as a result of methodological improvements in the sphere of chemical synthesis, which can be used for the study of conformations and interactions with protein-receptor molecules. Such work is of particular importance because the oligosaccharide chains of glycoproteins and glycolipids anchored to the plasma membrane are important in cell-cell interactions and are receptors for enzymes, hormones, proteins, and viruses ; furthermore, they determine the antigen properties of cells. The methods of synthesis available for the production of selective linkages in oligosaccharides are dealt with, particular attention being paid to conversion of saccharides into oligosaccharides, which are important from the biological point of view.

The intriguing dual-directing effect of 2-cyanobenzyl ether for a highly stereospecific glycosylation reaction

“…Optimizing experiments were first conducted with common activating conditions, such as NIS/AgOTf, NIS/TMSOTf and Ph 2 SO/Tf 2 O/TTBP ( In general, the structure of glycosyl acceptors only shows complementary effects 28 on stereoselectivity of a glycosylation reaction, compared with the structure of donors [29][30][31] , and other factors such as temperature or solvents. Glycosyl acceptors bearing electron-withdrawing substituents should diminish the nucleophilicity of the hydroxyl group, resulting in a decrease of reaction rate 29,32 . This could improve selectivity as the reaction can be carried out in a more controlled manner 33 .…”

Carbohydrates in peptide and protein design

“…The chemistry of glycopeptide synthesis is covered by extensive reviews, 1,15 and only a few general considerations shall be outlined here. The interdisciplinary field of glycopeptide synthesis was pioneered by Paulsen, 15 Kunz, and Meldal.…”

“…The interdisciplinary field of glycopeptide synthesis was pioneered by Paulsen, 15 Kunz, and Meldal. The first decision in the retrosynthetic planning is whether the carbohydrate moiety should be introduced by ''global'' glycosylation or through a ''building block'' approach.…”

“…16,17 Other N-and C-protecting groups have been used with success, as well as derivatives with a free carboxylate. 1,15 Glycosylation of a peptide offers the prospect of protection against proteolysis and improved aqueous solubility. A leading pharmaceutical example is the work by the Menarini group to improve the poor solubility of the potent, selective, conformationally constrained tachykinin NK 2 receptor antagonist, MEN 10627, cyclo-(Met-Asp-Trp-Phe-Dap-Leu)-cyclo-(2 -5 ).…”

Organic Synthesis and Biological Signal Transduction

“…[54][55][56] Classical chemical synthesis of oligosaccharide units of glycoproteins has also reached a high level of efficiency. [57] Figure 5…”