Conditions for neighboring-group participation in displacement reactions of 5-O-sulfonyl-d-glucofuranose derivatives

Abstract Sulfonate displacement reactions of 6- O -benzoyl-1,2- O -isopropylidene-5- O - p -tolylsulfonyl-α- d -glucofuranose derivatives with acetate or chloride ions in acetic anhydride are shown to involve participation by the neighboring benzoyloxy group. Acetate displacement in N,N -dimethylformamide appears to occur by both this and the S n 2 mechanism, but, with sodium azide in hexamethylphosphoramide, only the S n 2 displacement product was formed. Benzylidenation of 1,2- O -isopropylidene-β- l -idofuranose gave the 3,5- O -benzylidene derivative, and the reaction of this acetal with N -bromosuccinimide gave exclusively 5- O -benzoyl-6-bromo-6-deoxy-1,2- O -isopropylidene-β- l -idofuranose.