Synthesis of Per(5-carboxy-5-dehydroxymethyl)-α- and β-Cyclodextrins −Self-Assembly of the Per(2,3-di-O-methyl)-Protected Homologues into Highly Stable Dimers, Driven by Multiple Hydrogen Bonds

Abstract

Per(2,3-di-O-methyl)- and per(2,3-di-O-acetyl)- α- and β-cyclodextrins were smoothly converted into the corresponding per(5-carboxy-5-dehydroxymethyl) derivatives 2a, 2b, 4a and 4b by TEMPO-mediated oxidation. Alkaline hydrolysis of the per(2,3-di-O-acetyl)-substituted polycarboxylic acids affords the naked per(5-carboxy-5-dehydroxymethyl)cyclodextrins 5a and 5b in quantitative yields. Self-assembly, driven by hydrogen bonds, of the per(2,3-di-O-methyl)-protected homologues 2a and 2b affords highly stable dimers, as evidenced by vapour-pressure osmometry in 1,2-dichloroethane solution.