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Stereoselective Synthesis of Alkyl alfa-D-Glucopyranosides

100%

Kasprzycka A. , Pastuch G. , Cyganek A. , Szeja W.

tom Vol. 77 / nr 2

197-201

Glycosylation of _-D-glucosyl N-allyl thiocarbamates with alcohols using bromine as activator proceeded under mild conditions in a highly stereoselective fashion to afford the corresponding _-glucosides in high yields. Hindered tertiary alcohols can be also used as glycosyl donors.

Stereoselective One-Pot Synthesis of Isomaltooligosaccharides

100%

Pastuch G. , Wandzik I. , Szeja W.

tom Vol. 77 / nr 8

995-999

A highly stereoselective synthesis of _-linked (1_6)-gluco- di- and trisaccharides has been described. In this procedure two thioglucosides, (5-nitro-2-pyridyl) 1-thio-_- D-glucopyranoside and 6-O-tritylated ethyl 1-thioglucoside were applied as an acceptor and a donor respectively.

Glikozylacja z zastosowaniem pochodnych 1-tiocukrów jako substratów

63%

Szeja W. , Bugla J. , Niemiec A. , Pastuch G. , Kasprzycka A. , Ślusarczyk A. , Wandzik I. , Bieg T. , Przybysz B. , Bogusiak J.

Wiadomości Chemiczne

2002

tom [Z] 56, 7-8

605-625

It was found that carbohydrate part of complex glycosides may act as antigens or receptors for proteins, and these findings led to the discovery of the important role of carbohydrates in cell-cell recognition phenomena and cell differentiation. At the same time the methods of glycosylation underwent rapid development. The present paper gives an overview of development of 1-thiosugar derivatives in oligosaccharide synthesis. In the first part of this review, recent results of the use of thioglycosides, dithiocarbonates, dithiocarbamates and thiophosphates as glycosyl donors and acceptors are presented. A survey of important methods for the synthesis of thiosugars is presented, followed by discussion of methods converting anomeric substituent into a good leaving group (activation) in nucleophilic substitution reaction. The mechanism and procedures, which provide stereoselective formation of 1,2-cis and 1,2-trans glycoside bond, are discussed. The versatility of 1-thiosugar derivatives in synthetic carbohydrate chemistry is illustrated by selective activation strategies. The most important synthetic methodologies of the synthesis of oligosaccharides like linear glycosylation strategy in step-by-step and multistep "one-pot" sequence, "armed-disarmed" glycosyl donor, "latent-active" glycosylation, orthogonal strategy are illustrated on several examples. The last part is devoted to methods for solid support oligosaccharide synthesis.