Subtle Stereochemical and Electronic Effects in Iridium-Catalyzed Isomerization of C-Allyl Glycosides

Stereoselective isomerization of C-allyl glycosides into (E)-C-vinyl glycosides or (Z)-exo-glycals was carried out in the presence of the cationic iridium(I) catalyst [(Ph₂MeP)₂Ir(cod)PF₆]. The products of the isomerization were affected by the relative 1,2-stereochemical relationships and by the nature of the protecting groups. These effects are discussed along with a plausible reaction mechanism.