ChemInform Abstract: New Methods for the Synthesis of Glycosides and Oligosaccharides ‐ Are there Alternatives to the Koenigs‐Knorr‐Method?

Abstract

Dedicated to Professor Rudolf Gompper on the occasion of his 60th birthdayGlycoproteins, 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 1-0-alkylation, on the trichloroacetimidate method, and on activation through the formation of glycosylsulfonium salts and glycosyl fluorides.

Synthesis and antifungal activity of pradimicin derivatives. Modifications of the sugar part.

“…The glycosidation sites (5-or 6-OH) of the products was established by NOEsobserved between the anomeric proton (l'-H) and 5-or 6-H, and the coupling constant of Jv%2> value defined the stereochemistry of the anomeric center. 4'-Deoxy monosaccharide derivatives (7,8) were derived from dexylosyl PRMC (C) by successive treatment with NaNO2 and NaBH4 (Method C). Stereochemistry of the 3'eq-OH in compound8 was established by the coupling constants observed in *H NMR(Jr y =9.0, /3 j4'ax= 12.0 Hz).…”

Enzymatic Synthesis of Polyphenol Glycosides by Amylosucrase

“…이런 문제점은 폴리페놀의 당화과정 (glycosylation)을 통하여 합성된 배당체를 이용하여 극복할 수 있다. 배당체의 합성은 화학적 방법으로 가능하지만, 이런 방법은 고온, 고압을 포함하는 조건이 필수적이고 합성된 아 노머(anomer) 물질의 분리 및 환경문제 등을 야기하여 [18] 최 근에는 생물체가 지니는 당 전이 능력을 갖는 효소를 이용한 당 전이 반응(transglycosylation)을 통하여 빠르고 쉽게 생산 하고 있다 [8,13] (Fig. 2).…”

Taming the Reactivity of Glycosyl Iodides To Achieve Stereoselective Glycosidation

“…SciFinder had just become widely accessible, and using this tool we found that indeed, leaders in the carbohydrate synthesis field had routinely dismissed glycosyl iodides as too reactive to be useful. 1 The search also revealed that there had been some dabbling with glycosyl iodides in the 1970s, but no follow-up studies were reported. 2 Fortunately, the Beilstein database was also available, leading us to a rich carbohydrate literature going back to the early 1900s and the laboratories of Emil Fischer.…”