Glycosyl derivatives

More interesting are the substitution reactions on the triazole ring where a characteristically different course can be expected from that of analogous reactions in the purine series. These reactions were studied in more detail only in connection with the preparation of the glycosyl derivatives, and the experimental material does not permit the drawing of general conclusions. 

N-Glycosyl derivatives are conveniently named as glycosylamines. In the case of complex heterocyclic amines, such as nucleosides, the same approach is used. 

Fischer projection of acyclic form, 56-57 glycosides, 132-135 C-glycosyl compounds, 139-140 N-glycosyl derivatives, 137-139 glycosyl halides, 136-137 glycosyl residues, 125 isotopic substitution and isotopic labelling, 91 me so forms, 59 optical rotation, 59 parent structure choice, 53... 

C-Glycosyl derivatives may be prepared by utilizing glycosyl fluorides. Ishido and coworkers reported that the reaction of 2,3,5-tri-O-benzyl-a-(36a) or - -D-ribofuranosyl fluoride (36fi) with isopropenyl trimethylsilyl ether under BF3 catalysis (0.1 -0.05 mol. equiv. for the fluoride, in ether or acetonitrile) gave a mixture of 4,7-anhydro-5,6,8-tri-C)-benzyl-l,3-dideoxy-D-altro- (139, major) and -D-a//o-2-octulose (140) 139 was stated to isomerized to 140 (should be vice versa) under Lewis acid catalysis. Similar... 

A straightforward discrimination between the two pathways is possible with enzymes that are inhibited by basic glycosyl derivatives as well as by permanently cationic ones. This is illustrated by )S-D-glucosidase A3 from Asp. wentii, where K4 values for yS-D-glucosylpyridinium ion, / -D-glucosyla-... 

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