Glycosides configuration

D-fructofuranoside. The methylation results did not determine the two alpha or beta glycosidic configurations about the biose junction, and XV, like II, therefore had four possible configurations. 

Methyl 2,2, 3,3 4, 6 -hexamethyl-j8-maltoside (4) has been converted to the mixture of alditol glycosides (5) as outlined in Scheme 1, which can form the basis of a method for the specific degradation of uronic acid-containing polysaccharides, mass spectrometry showing the site of linking, and n.m.r. spectroscopy the glycosidic configuration. ... 

Both maltose and cellobiose have a free anomeric hydroxyl group that is not involved in a glycoside bond The configuration at the free anomeric center is variable and may be either a or (3 Indeed two stereoisomeric forms of maltose have been iso lated one has its anomeric hydroxyl group m an equatorial orientation the other has an axial anomeric hydroxyl... 

AC2O, FeCl3, Et20, 76-93% yield." These conditions give the acetate of the alcohol, which can then be cleaved by simple basic hydrolysis. The method is also effective for the conversion of r-butyl glycosides to acetates with retention of configuration (80-100% yield). 

Consequently, the glycosidic linkage in kasuganobiosamine must be -configuration, showing conversion of the anomeric proton during methanolysis. 

Debenzylidenation of compound 24 yielded a crystalline glycoside 25 and the extent and rate of its periodate oxidation supports the structure and configuration shown. 

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