Synthèse de l'apiose et de composés voisins par des réactions de wittig

Treatment of 1,2-O-isopropylidene-α-D-glycero-tetros-3-ulofuranose (7) with cyanomethylenetriphenylphosphorane gave in excellent yield a mixture of the geometrical isomers of the corresponding cyanomethylenic derivative. After treatment with potassium permanganate, and then with sodium borohydride, this unsaturated, branched-chain sugar derivative was stereospecifically converted into 3-C-hydroxymethy]-1,2-O-isopropylidene-β-L-threofuranose. Similarly, treatment of the L-enantiomer of 7 with methylthiomethylenetriphenylphosphorane gave the expected methylthiomethylenic analogs, from which 3-deoxy-3-C-methyl and 3-deoxy-3-C-dimethoxymethyl derivatives were prepared. Wittig reactions thus allow the synthesis of branched-chain sugars bearing the side-chain on the more hindered side of the ring, compounds which are difficult to obtain by other methods.