Introduction of a carboxyl group through an acetal as a new route to carboxylic acid derivatives of sugars

A new class of carboxylic acid derivatives of sugars is described. Acetalation of mono- and disaccharides with a functionalized vinylic ether or a diethoxybutanoate afforded mono- and diacetals bearing an ester group. Their saponification led to the corresponding carboxylic acid acetals in which the length of the acetal side chain can be modulated.