The title compound, previously unreported in either enantioform, and its 2,6-di-O-benzyl derivative have been synthesized through a stereocontrolled epimerization at C-2 of 6-O-protected methyl 3,4-O-isopropylidene-5-C-methoxy-beta-D-galactopyranosides. The epimerization, performed through a high yielding sequence of oxidation-reduction owing to the cooperative role of the equatorial C-1 aglycon and the steric hindrance of the isopropylidene group, turned out to be completely diastereoselective. Whereas the unprotected L-ribo-hexos-5-ulose exists, as proved by NMR in D2O, in five main tautomeric forms in a ratio of about 4:2:2:1:1, only two anomeric 1,4-furanosic forms are present at equilibrium in its 2,6-di-O-benzyl derivative, in ratios ranging from 10:1 to 7:3, depending on the prevalence of D2O or CD3CN in the solvent mixture.
|Autori:||BARILI PL; BERGONZI MC; BERTI G; CATELANI G; D'ANDREA F; DE RENSIS F.|
|Titolo:||The first synthesis of a ribo-hexos-5-ulose: the L-enantioform|
|Anno del prodotto:||1999|
|Digital Object Identifier (DOI):||10.1080/07328309908544053|
|Appare nelle tipologie:||1.1 Articolo in rivista|