Oligosaccharides reaction

Keywords Biocatalysis, Enzyme engineering, Fructosyltransferases, Glucosyl-transferases, Immobilization, Oligosaccharides, Reaction engineering... 

The glucose dithioacetal and certain others decompose at room temperature in the reaction mixture by giving alkyl 1-thioglycopyranosides. This class of compounds has gained a certain importance in the synthesis of oligosaccharides (reaction 10.4). They are prepared more commonly in the peracetylated form as 6J, by treating the )3-peracetate of the pyranose with a thiol in the presence of BF3.OEt2. 

Transglycosylation. Ea2ymatic transglycosylatioas allow preparatioa of various oligosaccharides that caimot be made readily by stricdy chemical means. The reaction can be expressed as... 

Dioxolane derivatives, which are obtained from methoxybutenone and glycols and used as antifungicides, and squalene synthetase inhibitors have been described (94MI1). The reactions of mono- and oligosaccharides with... 

Extensive work has been done by using buta-l,3-dienyl-glycosides of unprotected sugar to study aqueous Diels-Alder reactions and to prepare optically active oligosaccharides [20]. 

Treatment of 51 with an excess of sodium benzoate in DMF resulted in substitution and elimination, to yield the cyclohexene derivative (228, 36%). The yield was low, but 228 was later shown to be a useful compound for synthesis of carba-oligosaccharides. <9-Deacylation of228 and successive benzylidenation and acetylation gave the alkene 229, which was oxidized with a peroxy acid to give a single epoxide (230) in 60% yield. Treatment of 230 with sodium azide and ammonium chloride in aqueous 2-methoxyeth-anol gave the azide (231,55%) as the major product this was converted into a hydroxyvalidamine derivative in the usual manner. On the other hand, an elimination reaction of the methanesulfonate of 231 with DBU in toluene gave the protected precursor (232, 87%) of 203. 

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