The title sulfonium salta undergo electrophilic addition to glycals in the presence of alcohols to form principally b-glycosides. A substituent effect study has shown that the reagent with a ptolylthio group is the most face-selective. By variation of the alcohol nucleophile, it has been shown that face selectivity is also dependent on the structure of the nucleophile. One instance of double diastereodifferentiation was uncovered when the racemic alcohol 23.5 ...
