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)]

It is a privilege to be able to contribute to this volume in which Professor Zervas’ friends, students, and colleagues have joined together to honor him and his remarkable contributions to peptide chemistry. Although I did not know him until after his days in the Bergmann Laboratory at the Rockefeller Institute, I can claim the distinction of now working in those very same rooms that they occupied back in the mid-1930s. Like all peptide chemists, I am greatly indebted to Professor Zervas, having depended so heavily on the carbobenzoxy group and on the various modified urethan protecting groups which have been direct extensions of the revolutionary advance that Bergmann and Zervas made.

Solid-phase peptide synthesis.

Polymers for biodegradable medical devices. 1. The potential of polyesters as controlled macromolecular release systems

Antitumor effect of hexa-N-acetylchitohexaose and chitohexaose

Glycoproteine, Glycolipide und Glycophospholipide (=Glycokonjugate) sind Bestandteile von Membranen. Dabei ist der oligosaccharidische Teil fur Zell-Zell-Erkennung und -Wechselwirkung zustandig; er fungiert als Rezeptor fur Proteine, Hormone und Viren und determiniert Immunreaktionen. Diese Bedeutung hat das Interesse an Oligosacchariden und Glycokonjugaten stimuliert. Mit ihnen sollte es gelingen, die molekulare Basis dieser Phanomene aufzuklaren und neue physiologische Wirkprinzipien abzuleiten. Grose Fortschritte der Oligosaccharidsynthese sind mit der Koenigs-Knorr-Methode erzielt worden, bei der Halogenosen in Gegenwart von Schwermetallsalzen zur Glycosylubertragung auf Nucleophile dienen. Die Nachteile dieses Verfahrens haben zu einer intensiven Suche nach neuen Methoden gefuhrt. In diesem Beitrag werden solche Methoden diskutiert. Dabei ist insbesondere auf die Glycosid- und Saccharidbildung durch 1-O-Alkylierung, auf die Trichloracetimidat-Methode und auf die Aktivierung uber Glycosylsulfoniumsalze und Glycosylfluoride hinzuweisen.

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Neue Methoden zur Glycosid- und Oligosaccharidsynthese – gibt es Alternativen zur Koenigs-Knorr-Methode?

Publisher Summary This chapter analyzes the preparation of anhydro sugar derivatives that are appropriate starting materials for the synthesis of stereoregular polysaccharides and discuses the methods and mechanisms of polymerization, properties, and characterization of the resultant polymers and their developing applications The two best-known syntheses of anhydro sugars are those of 1,6-anhydro-β- d -glucopyranose by the alkaline treatment of phenyl β- d- glucopyranoside and of the Brigl anhydride by the treatment of 3,4,6-tri- O -acetyl- β- d -glucopyranosyl chloride with ammonia A number of anhydro sugar derivatives have been prepared by the treatment of orthoesters with mercuric bromide in nitromethane There are the two characteristic classes of polymerization process—step growth and chain growth Currently, minimal structural information is available on 1,3-anhydroaldopyranose polymers, and exploratory studies on alternative catalyst systems are required The variable selectivity in polymerizations of the 1,4-anhydroaldopyranoses suggests that a systematic investigation of substituent groups, catalysts, and polymerization conditions should lead to stereoregular, (1→4)-linked polysaccharides If all the challenges are met and comparable progress can be made with the furanosides, there will still be the challenge of the synthesis of regularly ordered copolymers and cis -linked, rather than trans -linked polysaccharides

Conrad Schuerch

Papers

Synthesis and Polymerization of Anhydro Sugars

Methanolysis as a model reaction for oligosaccharide synthesis of some 6-substituted 2,3,4-tri-O-benzyl-D-galactopyranosyl derivatives

Synthesis of .alpha.-(1 .fwdarw. 3)-branched dextrans by copolymerization and .alpha.-D-glucosidation

Synthesis of a substituted 2,6-dioxabicyclo[3.1.1]heptane,1,3-anhydro-2,4,6-tri-O-benzyl-β-d-glucopyranose

Configuration and optical activity of vinyl polymers