Subtle Stereochemical and Electronic Effects in Iridium-Catalyzed Isomerization of <i>C</i>-Allyl Glycosides

Stereoselective isomerization of <i>C</i>-allyl glycosides into (<i>E</i>)-<i>C</i>-vinyl glycosides or (<i>Z</i>)-<i>exo</i>-glycals was carried out in the presence of the cationic iridium(I) catalyst [(Ph<sub>2</sub>MeP)<sub>2</sub>Ir(cod)PF<sub>6</sub>]. 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.