Glycofuranosides other methods

Certain other articles in this Series have discussed the glycofuranosides in part -4 preparative methods for several of them have been reviewed elsewhere.7... 

Although hydrogen chloride has been the catalyst principally employed in the Fischer method, other acids, notably sulfuric acid, have been used, as well as acidic, ion-exchange resins.66-19 The advantage of the latter reagents is that the insoluble resin can be readily filtered from the reaction solution. It is held that the replacement of soluble acids by insoluble resins does not appreciably alter the formation of the glycofuranosides. 

In Table VII is given a list of products obtained by this method the preponderant anomer obtained is the trans-l, 2-glycofuranoside (18), an effect similar to that noted for products formed by the Fischer method (see Table II on p. 105). The data in Table VII are limited in scope the yields are mostly preparative, and do not represent quantitative recoveries. In only four of the examples cited are the yields above 50%. The 91% yield of the anomers of ethyl L-rhamnofuranoside was obtained by separation on a chromatographic column, and represents the only quantitative information on this method. In all other examples, the products were isolated by crystallization techniques, and it has often been assumed that the crystalline product isolated, often in low yield, had been the preponder-... 

The glycofuranosides have been reviewed in this Series by Green.157 Several methods other than the Koenigs-Knorr method have been reported for the preparations of glycofuranosides. Glycosidation... 

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See also in sourсe #XX -- [ , , , , , , ]

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