Practical and convenient modifications of the A,C-secondary hydroxyl face of cyclodextrins

A practical and convenient method for the preparation of α-, β-, and γ-cyclodextrin derivatives, in which the secondary hydroxyl faces of A- and C-glucose units are regioselectively modified, has been developed. Reactions of α-, β-, and γ-cyclodextrins with 1,4-dibenzoylbenzene-3′,3″-disulfonyl imidazole in N,N-dimethylformamide in the presence of molecular sieves regioselectively afforded the corresponding cyclic 2A,2C-(1,4-dibenzoylbenzene-3′,3″-disulfonyl)-cyclodextrins. Subsequent treatment of the sulfonylated cyclodextrins with sodium hydroxide or aqueous ammonia afforded the corresponding 2A,3A:2C,3C-di-manno-epoxy-cyclodextrins or 3A,3C-diamino-3A,3C-dideoxy-(2AS,2CS,3AS,3CS)-cyclodextrins, respectively, which can serve as important intermediates for further functionalizations of the cyclodextrins.