Activated sugars

J. Seibel, K. Buchholz, and H. J. Jordening, Glycosylation with activated sugars using glycosyltransferases and transglycosidases, Biocatal. Biotransformation, 24 (2006) 311-342. 

This review summarizes recent approaches towards the selective formation of anomeric aldose and aldulosonic acid phosphates of biological relevance, in particular as precursors for the synthesis of nucleotide-activated sugars. 

The synthesis of these important compounds is very well explored. They can be now prepared almost routinely by a number of methods including the RCM cyclization of the properly activated sugar diolefins, 1,3-dipolar cycloaddition of nitrones and olefins (recent review ref. 6) or other types of cyclizations. 

Another approach to higher carbon sugars is based on the Wittig-type condensation between two properly activated sugar sub-units. The... 

Hofmann and Ohlerich (28) found that the same quantity of sulfur was taken up at 600° by activated sugar charcoal before and after covering with surface oxides. About equivalent amounts of oxygen and sulfur were bound by the same charcoal. A similar observation had been made by Baraniecky, Riley, and Streeter (126) who charred cellulose in the presence of hydrogen sulfide. The sulfur content corresponded to the oxygen content of samples treated similarly in the presence of air. 

Scheme 15 General mechanism of glycosylation. The hydroxyl group of serine attacks the activated anomeric carbon of UDP-activated sugars.

Many sugar isomerases are activated by Three Mn " " activated sugar isomerases have been... 

In the aim to prepare isosteric analogs of nucleotide-activated sugars, this straightforward method was applied to the preparation of C-glycosides related... 

We therefore needed a ready synthesis of the 1,6-epithio epoxide 119. Normally, for such syntheses, the sulftir atom is introduced at an early stage [64]. However, it appeared to us that a suitable doubly-activated sugar such as 120 should be capable of direct conversion to the 1,6-epithio sugar 121 by treatment with some type of sulfur reagent. Indeed, the o-glucosyl bromide 122 was easily prepared and, upon treatment with either hydrogen sulfide and triethylamine in DMF or benzyltriethylammonium tetrathiomolybdate in chloroform, gave the... 

The formulas in Sections II-VI usually represent, for simplicity, molecules belonging to the D configurational series, although they actually refer to racemic mixtures. Section VII deals with the preparation of optically active sugars in this Section, the formulas indicate the true configuration of the molecules. 

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