Glycoproteins, glycolipids, and glycophospholipids (glycoconjugates) are components of membranes. The oligosaccharide residue is responsible for intercellular recognition and interaction; it acts as a receptor for proteins, hormones, and viruses and governs immune reactions. These significant activities have stimulated interest in oligosaccharides and glycoconjugates. With their help it should be possible to clarify the molecular basis of these phenomena and to derive new principles of physiological activity. Major advances in the synthesis of oligosaccharides have been made by the use of the Koenigs-Knorr method, in which glycosyl halides in the presence of heavy-metal salts are employed to transfer the glycosyl group to nucleophiles. The disadvantages of this procedure have led to an intensive search for new methods. Such methods will be discussed in this article. Emphasis is placed on glycoside and saccharide formation by 1-O-alkylation, on the trichloroacetimidate method, and on activation through the formation of glycosylsulfonium salts and glycosyl fluorides.

New Methods for the Synthesis of Glycosides and Oligosaccharides—Are There Alternatives to the Koenigs‐Knorr Method? [New Synthetic Methods (56)]

Stereochemistry and the mechanism of enzymatic reactions

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.

Advances in Selective Chemical Syntheses of Complex Oligosaccharides

Increased understanding of the important roles that oligosaccharides and glycoconjugates play in biological processes has led to a demand for significant amounts of these materials for biological, medicinal, and pharmacological studies. Therefore, tremendous effort has been made to develop new procedures for the synthesis of glycosides, whereby the main focus is often the formation of the glycosidic bonds. Accordingly, quite a few review articles have been published over the past few years on glycoside synthesis; however, most are confined to either a specific type of glycoside or a specific strategy for glycoside synthesis. In this Review, new principles for the formation of glycoside bonds are discussed. Developments, mainly in the last ten years, that have led to significant advances in oligosaccharide and glycoconjugate synthesis have been compiled and are evaluated.

New principles for glycoside-bond formation.

Zur Permethylierung von Zuckern und Glykosiden

Glucosid-artige Derivate der Purinbasen sind im Tier- und Pflanzenreiche wiederholt beobachtet worden. Am langsten bekannt ist das Guanosin oder Vernin, das von E. Schulze und seinen Schulern1) als Pflanzenstoff entdeckt, spater als Spaltprodukt der Nucleinsauren zu so groser Wichtigkeit gelangt ist, und dessen Charakterisierung als Guanin-d-ribosid wir den schonen Arbeiten von P. A. Levene und W. A. Jacobs verdanken2).

Burckhardt Helferich

Papers

Synthetische Glucoside der Purine

Zur Synthese von Disacchariden IV. Zwei Tetra‐acetyl‐β‐d‐glucosen

Über neue synthetische Glucoside

Synthese eines Disaccharid‐glucosids

Eine neue ungesättigte Anhydro‐glucose