Acetolysis of monosaccharide derivatives

Only two comparisons of acetolysis of secondary-secondary methylene acetals were made 1,6-di- O-benzoyl-2,4 3,5-di-O-methylene-D-glucitol 

Prolonged treatment of 1,3-erythro methylene acetals of alditols does, however, cause their acetolysis.  

Trifluoroacetic anhydride-acetic acid, when used for the acetolysis of methylene acetals of alditols, shows the same specificity as acetic anhydride-sulfuric acid. - However, the products formed can be converted, by very mild hydrolysis, into the acetate-hydroxy derivative (6), because of facile cleavage of the (trifluoroacetoxy) methyl ether linkage (5). 

No acetolyses appear to have been performed on methylene acetals of aldoses or aldosides. The use of the trifluoroacetic anhydride-acetic acid sequence would be one way of protecting a primary hydroxyl group and freeing a particular secondary one. 

The only examples of the acetolysis of ethylidene acetals appear to be the conversion of methyl 2,3-di-0-acetyl-4,6-0-ethylidene-/3-D-glucoside 

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