Derivatives Of α-Cyclodextrin and the Synthesis of 6-O-α-D-Glucopyranosyl-α-Cyclodextrin

Regioselective silylation of α-cyclodextrin with tert -butyl-dimethylsilyl chloride in N, N -dimethylformamide in the presence of imidazole gave, in 75% yield, the hexakis(6- O - tert -butyldimethylsilyl) derivative 2, which was transformed into the hexakis(2,3-di- O -methyl, 6- O -methyl, 2,3-di- O -propyl, and 2,3-di- O -acetyl) derivatives. On methanesulfonylation and p-toluenesulfonylation, the hexakis(2,3-di- O -acetyl) derivative 16 afforded the hexakis(2,3-di- O -acetyl-6- O -methylsulfonyl 17 and 2,3-di- O -acetyl-6- O -p -tolylsulfonyl 18 ) derivatives, respectively. Nucleophilic displacement of 17 and 18 with iodide, bromide, chloride, and azide ions afforded the hexakis(6-deoxy-6-iodo 19 , 6-bromo-6-deoxy, 6-chloro-6-deoxy, and 6-azido-6-deoxy) derivatives, respectively, of α-cyclodextrin dodeca-acetate. The hexakis (2, 3-di- O -acetyl-6-deoxy) derivative was prepared from 19 . Selective glucosylation of 16 with 2,3,4,6-tetra- O -benzyl-α-D-glucopyranosyl bromide under catalysis by halide ion, followed by removal of protecting groups, furnished 6- O -α-D-glucopyranosyl-α-cyclodextrin.