The stereoselectivities in the 1,2-addition of nucleophiles such as methylmagnesiumiodide, vinylmagnesium bromide, and 2-lithio-2-methyl-1,3-dithiane to seven kinds of 4-uloses were examined. The configurations of C-vinyl derivatives obtained were determined from the chemical shifts of α-carbons in 13C-NMR spectra.
Branched-chain Sugars. XXII. Synthesis of Benzyl 2,3-Di-<i>O</i>-benzyl- and 2,3-<i>O</i>-Methylene-β-L-<i>threo</i>-pentopyranosid-4-uloses, and the Corresponding 6-Deoxy-α-D-<i>xylo</i>-hexopyranosid-4-uloses
The title compounds were synthesized from L-arabinose and D-glucose as intermediates to a few naturally occuring branched-chain sugars. Oxidation conditions of precursors to the corresponding 4-uloses were examined.