Binding and Catalytic Properties of 2-O- and 3-O-Permethylated Cyclodextrins

Hexakis(3-O-methyl)-i-cyclodextri n( 3i) bound to m- and p-nitrophenolate ions more strongly, whereas hexakis(2O-methyl)-i-cyclodextri n( 2i) bound less strongly than native i-cyclodextrin. ROESY spectra showed that the 3-Omethyl groups of 3i interact with the guest protons, whereas 2-O-methyl groups of 2i do not. 3i accelerated and 2i decelerated the cleavage of m-nitrophenyl acetate i na n alkaline solution, suggesting that the C(2)IOH of i-cyclodextrin is more catalytic than the C(3)IOH. However, the catalyti ce ffect of 3i was much smaller than that of native icyclodextrin. Loss of hydrogen bonding between the C(3)IOH and C(2)IOH by 3-O-permethylation is responsible for the small catalyti ce ffects of 3i .S imilar results were obtained for ¢-cyclodextrin analogs.