Communication: A Convenient Synthesis of Per-O-Methylated 6-O-Monosubstituted ß-Cyclodextrins

This is the authors' abstract. We don't add key points for this paper.

Cyclodextrins are cyclic oligosaccharides that function as chiral host molecules exhibiting enantioselectivity in reactions with racemic guests1 and thus they represent a significant moiety of artificial enzymes.2 The most easily obtainable and relatively inexpensive are ß-cyclodextrins (ß-CD), cyclic heptaglucosides in which glucopyranosyl residues are linked by an α(1-4) glycosidic bonds. ß-CD is surprisingly poorly soluble in water (1.8 g in 100 mL)3 but the solubility of its derivatives is often significantly better. For instance, ß-CD with all secondary hydroxyls methylated, forms 50% aqueous solutions at room temperature,4 and even completely methylated ß-CD is ten times more soluble in water (17 g in 100 mL)5 than ß-CD itself. Methylation also alters the binding of the substrates to ß-CD often increasing its specificity and strength,6 and renders the hydroxyl groups unreactive. Therefore, it is of interest to prepare derivatives of ß-CD in which the enzyme-mimicking group is bound to one hydroxyl (possibly through a tether) while the rest of the ß-CD moiety is permethylated.