Preparation of 2A,3A-alloepimino-2A,3A-dideoxy-β-cyclodextrin as a versatile scaffold candidate for the hetero-2A,3A-bifunctionalization

3A-Azido-3A-deoxy-altro-β-cyclodextrin, although having as many as 20 different hydroxyl groups, was selectively sulfonylated at the 2A-OH of the altrose residue by 2-mesitylenesulfonyl chloride to give 3A-azido-3A-deoxy-2A-O-mesitylenesulfonyl-altro-β-cyclodextrin. A one-pot reduction–intramolecular substitution of the latter afforded the title compound as a promising intermediate for the introduction of two different functional groups to two different positions of one sugar unit, which has not been succeeded hitherto.