Cyclodextrin ketones as oxidation catalysts: investigation of bridged derivatives.

A series of alpha-cyclodextrin derivatives containing a 3, 4 or 5 membered ether-linked bridge between the 6A and 6D oxygen atoms, with and without a ketone, were prepared. The synthesis used perbenzylated alpha-cyclodextrin A,D-diol as a starting material upon which O-alkylation and further modifications led to the di-O-(buta-1,4-diyl), the di-O-(penta-1,5-diyl) and the di-O-(buta-2-on-1,4-diyl) derivatives, which were debenzylated, and compared with the previously reported di-O-(propa-2-on-1,3-diyl) derivative. Permethylated derivatives of the di-O-(propa-2-on-1,3-diyl) and the buta-1,4-diyl derivatives were also made. The 6A,6D-di-O-(propa-2-on-1,3-diyl)-6C,6F-di-O-methyl and di-O-pivaloyl derivatives were also prepared. The new compounds were analysed for catalysis of the oxidation of amines and alcohols.