Aspects of the chemistry of oximes derived from methyl hexopyranosiduloses

Abstract

Oximation of methyl 4,6-O-benzylidene-2-deoxy-α-D-erythro-hexopyranosid-3-ulose (1) afforded one oxime with the syn-structure, whereas oximation of the threo-isomer (4) afforded products with the syn- and anti-structures, as determined from their n.m.r. spectra. A detailed study of these spectra enabled an assignment of the C-2 methylene signals in the spectra of the parent glycosiduloses. In both compounds (1) and (4) the axial methylene proton resonates downfield from the equatorial one. In contrast to a literature report we find that oximes derived from compounds (1) and (4) can be reduced by the usual reagents. The former gave almost exclusively the amine with the D-ribo-configuration whereas the latter gave a mixture of amines with the D-lyxo- and D-xylo-configurations. The reduction of the parent uloses (1) and (4) has also been examined. The stereochemistry of these reductions is discussed.