Modification of cyclodextrins by insertion of a heterogeneous sugar unit into their skeletons. Synthesis of 2-amino-2-deoxy-β-cyclodextrin from α-cyclodextrin

Abstract

Acetolysis of fully acetylated α-cyclodextrin 5a resulted in restricted fission of only one of the glycosidic bonds to give the acyclic maltohexaose peracetate 6a in 46% yield. Regioselective modifications of both terminals of hexasaccharide 6a were performed by employing Lewis acid-catalysed thioglycosidation and O-benzylidenation followed by its reductive cleavage as the key reactions, to give the partially O-benzylated maltohexaoside 9a with the sole hydroxy group at the 4^VI-position. Coupling of compound 9a and a D-glucosamine precursor by the trichloroacetimidate method gave the heptasaccharide 15, subsequent deprotection of which gave 2-amino-2-deoxy-β-cyclodextrin 1.