Application of the Oxo Reaction to Anhydro Sugars Having an Ethylene Oxide Ring

Application of the Oxo Reaction to Anhydro Sugars Having an Ethylene Oxide Ring 

The anhydro sugars were allowed to react with carbon monoxide and hydrogen (or methanol) in the same equipment used in the application of the 0X0 reaction to unsaturated carbohydrates. It was essential, however, that all reactants be anhydrous, and that the equipment be assembled in a dry-box, because traces of moisture cause hydrolysis of the anhydrides. 

In addition, its proton magnetic resonance spectrum unambiguously supported the 5-ketose structure (69). Rearrangements of epoxides to ketones when dicobalt octacarbonyl is used as the catalyst at temperatures above 100 , or when cobalt hydrocarbonyl is used at lower temperatures, are well known. By applying the technique of double irradiation to a sample of (68), the main component was shown to possess structure (68). Presumably, the free aldehyde group of the hydroformylation product immediately cyclized with the free hydroxyl group on C-3 to give the tricyclic structure (68). A third component (68a) (isolated in less than 5 % yield) was undoubtedly formed by subsequent reduction of the dialdose derivative (68). 

When 5,6-anhydro-l,2-0-isopropylidene-a-I -glucofuianose (67) in ether was allowed to react with carbon monoxide (12 atmospheres, at room temperature) in the presence of sodium cobalt tetracarbonyl for 3 days, the stoichiometric amount of carbon monoxide was absorbed. The mixture was cooled to —5 , and subsequent treatment with methanol and iodine by the procedure of Heck and Breslow resulted in the formation (in 80 % yield) of the methyl uronate (70) and, in a yield of about 10%, the 6-deoxy-hexos-5-ulose (69). Reduction of the methyl uronate (70) and of the dialdose derivative (68) with lithium aluminum hydride yielded identical sugars. 

Fusion of 5,7-di-0-acetyl-6-deoxy-l,2-0-isopropylidene-a-D-gittco-heptodialdo-l,4-furanose-7,3-pyranose (71) with 5,6-dimethylbenzi-midazole, with monochloroacetic acid as the catalyst according to the 

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