Hetero-bifunctionalization of the secondary face of β-cyclodextrin: selective 3G-sulfonylation and subsequent 2G,3G-epoxidation of 3A-azido-3A-deoxy-altro-β-cyclodextrin

3A-Azido-3A-deoxy-altro-β-cyclodextrin, which has 20 different hydroxyl groups, was selectively sulfonylated by 1-naphthalenesulfonyl chloride at the 3G-OH of the glucoside residue as well as the 2A-OH of the altroside one. Alkali treatment of the 3G-sulfonate gave successfully the 2G,3G-epoxyalloside with the 3A-azido group being left unaffected. Both the 3G-sulfonate and 2G,3G -alloepoxide species of 3A-azido-3A-deoxy-altro-β-cyclodextrin not only have two sugar units being modified differently, but also can serve as versatile starting materials for the syntheses of bifunctional cyclodextrins with diverse combination of different functionalities.