Stereoselective Formation of 1,4-Anhydro-2-C-carboxytetritols in the Degradation of 1,5-Anhydroribitol and 1,5-Anhydroxylitol with Oxygen in Aqueous Alkali
2006
Schroeder, L.R. | Millard, E.C.
In addition to other acid products, degradation of 1,5-anhydroribitol (5) and 1,5-anhydroxylitol (6) with oxygen in 1.25 M NaOH produced diastereomeric 1,4-anhydro-2-C-carboxy-D-erythritol (7) and 1,4-anhydro-2-C-carboxy-D-threitol (8) and their enantiomers as major products. However, the ratio of the diastereomers differed for the two reactants. Thus, their formation could not proceed solely by benzilic acid-type rearrangements through α-dicarbonyl intermediates as typically proposed for formation of alkyl C-carboxyfuranosides from alkyl glycopyranosides in similar reactions. The α-dicarbonyl species that can form from 5 and 6 are identical. Potential mechanisms to account for stereoselective formation of 7 and 8 are presented.
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