Practical and convenient modifications of the A,C-secondary hydroxyl face of cyclodextrins
Tetrahedron 59(14): 2519-2538, 31 March
ISSN/ISBN: 0040-4020 DOI: 10.1016/s0040-4020(03)00259-x
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 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.