Stereoselectivity of the nucleophilic F-alkylation of carbonylated carbohydrates

Article abstract of DOI:10.1016/S0957-4166(97)00620-4

The addition of F-alkyl organometallics to carbonylated carbohydrates 1-3 was carried out using trimethylsilyl or bromomagnesium reagents. The results are strongly dependent upon both the nature of the metal and of the substrate. Compounds 1 and 2 were transformed with high stereoselectivity into the L-ido adduct using F-organomagnesium reagents, whereas the D-allo adduct was obtained with complete stereoselectivity using fluoride activated addition of F-organosilanes on compound 3. Comparison with literature data emphasizes the enhanced stereoselectivity exhibited by perfluoroorganometallic reagents. The difference between the stereoselectivity of the addition of magnesium versus silyl reagents was attributed to chelation effects.