Utilisation d'ylides du phosphore non stabilisés en chimie des sucres VI. Sucres ramifiés dérivés des di‐O‐isopropylidène‐1,2:5,6‐α‐<scp>D</scp>‐<i>ribo</i>‐et‐α‐<scp>D</scp>‐<i>xylo</i>‐hexofurannosul‐3‐oses

Abstract

Abstract The cis and trans isomers of 3‐deoxy‐1,2:5,6‐di‐O‐isopropylidene‐3‐C‐methylthiomethylene‐α‐ D ‐ xylo ‐ and ‐α‐ D ‐ ribo ‐hexofuranoses have been prepared by treatment of 1,2:5,6‐di‐O‐isopropylidene‐α‐ D ‐ xylo ‐ and ‐α‐ D ‐ ribo ‐hexofuran‐3‐uloses with methylthiomethylene‐triphenylphosphorane. Configurations are assigned by NMR. A new type of 4 J is described. Hydrogenation‐desulfurization of the methylthiovinylic sugars affords 3‐deoxy‐3‐methyl sugars of the D ‐ allo , D ‐ gulo , and D ‐ galacto series. Derivatives of 3‐deoxy‐3‐methyl‐ D ‐lyxose and 3‐deoxy‐3‐methyl‐ D ‐ribose are prepared by chain‐shortening of derivatives of the corresponding 3‐deoxy‐3‐methyl‐hexoses.