Action de nucléophiles sur des sucres ramifiés cyanovinylidéniques: Addition conjuguée,stéréomutation,migration de doubles liaisons. Communication préliminaire

When treated with a series of nucleophiles cis-3-cyanomethylene-3-deocy-1,2:5,6-di-O-isopropylidene-α-D-ribo-hexofurannose ( 1 ) may yield its trans isomer, a product of allylic isomerization or a product of conjugate addition, depending on the nature of the nucleophile. The configuration of the starting material is also important as shown by the differences in reactivity between 1 and its trans-xylo isomer 8 .