Glycosides selective, enzymic

It was of interest to determine whether glycosides of 6-deoxy-D-xylo-hex-5-enopyranose were susceptible to enzyme hydrolysis by / -glucosi-dase. Since aromatic glucosides are hydrolyzed by this enzyme at a much faster rate than aliphatic glycosides, phenyl 6-deoxy-/ -D-rt/Zo-hex-5-enopyranoside (18) was prepared (20). Phenyl / -D-glucopyranoside was converted to the 6-tosylate by selective esterification and then, by conventional procedures, transformed to phenyl 2,3,4-tri-0-acetyl-6-deoxy-... 

Selective Trimming of Natural Glycosides with Hydrolytic Enzymes... 

If both anomers of the glycoside are obtained in a reaction, it is necessary to separate them. One separation method that has been used is the preferential extraction101 of the anomers with a volatile solvent. After extraction of the individual glycoside, the solvent is removed by evaporation, and the glycoside may be obtained in crystalline form. A second method of separation utilizes fractional recrystallization, and it may be possible by proper selection of the solvent to obtain both anomers in crystalline form. A third method utilizes chromatography for separating the anomers, and the pure anomers may be obtained from appropriate fractions from the column. The anomeric configuration of the anomers which have been obtained in pure form will need to be determined. Such determinations can be made by measurement of physical constants, from the n.m.r. spectra, and from the susceptibility of the anomer to enzymes of known specificity. 

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