Secondary Alcohol Groups in Carbohydrates to Ketones

Examples of such oxidations are listed in Table 2.3 with furanoses listed first in a roughly alphabetical arrangement mainly by substituent groups of products. Some large-scale oxidations ( 1 g) are listed in the first column. The effective oxidant in most cases is RuO, with a few by [RuO ] or [RuO ] . For oxidations by RuO the overall stoicheiometry of the reaction was shown [312] to be 

In pyranoses RuO -based reagents oxidise equatorial or axial groups with equal ease [312, 317], 

Methyl-3,6-di-0-benzoyl-2-deoxy-a-D- Methyl-3,6-di-0=-benzoyl-2-deoxy-a-D-t/ reo-hexosid-4-ulose S [317] 

Methyl 4,6-0-benzylidene-2-0-toluene-p-sulfonyl-a-D-glucopyranoside (2 g [317]) Methyl 4,6-0-benzylidene-2-0-toluene-p-sulfonyl-a-D-n o-hexopyranosid-3-ulose E [330], S [317] 

Methyl 4,6-0-benzylidene-2-deoxy-a-D- Methyl 4,6-0-benzylidene-2-deoxy-a-L-e 7t/ ro-hexopyran-3-uloside S [323] 

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Although these encompass primary and secondary alcohols they are considered here in a separate section since so much work has been done in the area, using RuO as the oxidant. In most cases it was used for oxidation of secondary alcohol groups in carbohydrates to ketones, but its first application, albeit stoicheiometrically as RuOy CCy was for the conversion of a secondary alcohol unit in l,2 5,6-di-0-isopropy-lidene-a-D-glucofuranose to the D-nfeo-hexofuranos-3-ulose (Fig. 2.13) [310]. There are early but illuminating reviews on carbohydrate oxidations by RuO [18, 311]. 

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