Molecular magic.: Formation of a self-inclusion complex from a dumbbell-shaped permethylated β-cyclodextrin derivative

Hermaphroditic permethylated beta-cyclodextrins 1f and 2f and the relevant dumbbell-shaped CD dimers 3f and 4 were synthesized and their intramolecular complexation was examined by H-1 NMR methods. The dumbbell 3f was found to isomerize to a self-inclusion complex 3c at room temperature in CD3OD, but not 4. The isomerization was explained by means of a "somersault mechanism," which involves turning the glucose bearing the internal guest through 360degrees.