Methoxyl group, determination carbohydrates

The use of lead tetraacetate for adding acetoxy groups to a double bond, as here used for preparing the pentaacetate (76), has been widely applied in synthetic organic chemistry, but there have been only a few applications to carbohydrates (see Perlin s review in this Series, for other examples). The conversion of (76) to the dicarbonyl derivative (77) (in 65% yield and in the crystalline state) was made by autohydrolysis in water at room temperature for 3 hr. The structure was deduced from elemental analysis, acetyl analysis, and the absence of methoxyl groups, and from its mode of synthesis. The acetyl determination could be made by direct titration with... 

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