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

A practical and convenient method for the preparation of alpha-, beta-, and gamma-cyclodextrin derivatives, in which the secondary hydroxyl faces of A- and C-glucose units are regioselectively modified, has been developed. Reactions of alpha-, beta-, and gamma-cyclodextrins with 1,4-dibenzoylbenzene-3',3"-disulfonyl imidazole in N,N-dimethylformamide in the presence of molecular sieves regioselectively afforded the corresponding cyclic 2(A),2(C)-(1,4-dibenzoylbenzene-3',3"-disulfonyl)-cyclodextrins. Subsequent treatment of the sulfonylated cyclodextrins with sodium hydroxide or aqueous ammonia afforded the corresponding 2(A),3(A):2(C),3(C)-di-manno-epoxy-cyclodextrins or 3(A),3(C)-diamino-3 3(A),3(C)-dideoxy-(2(A)S,2(C)S,3(A)S,3(C)S)-cyclodextrins, respectively, which can serve as important intermediates for further functionalizations of the cyclodextrins. (C) 2003 Elsevier Science Ltd. All rights reserved.