Amino-acetone-bridged cyclodextrins - Artificial alcohol oxidases

Article abstract of DOI:10.1002/ejoc.200901099

A new series of α-and β-cyclodextrin derivatives containing a substituted amino-acetone bridge attached to the 6A and 6D positions of the cyclodextrin are reported. The synthesis starts from the known α-or β-cyclodextrin A,D-diols, which were either oxidized to α-or β-cyclodextrin A,D-dicarbaldehydes and then coupled with 1,3-diamino-2-propanol by a reductive amination reaction and further modified to give the final 6^A,6^D-diamino-6^A,6 ^D-dideoxy-N,N'-(2-oxopropa-1,3-dienyl)-N,N'-acetyl-α-or-β- cyclodextrin or the cyclodextrindiol was substituted with azide then reduced and after a few alkylation steps the final 6^A,6^D-dideoxy-N, N'-(2-oxopropa-1,3-dienyl)-6^A,6^D-(N,N,N'N'- tetramethyldiammonio)-α-cyclodextrin dibromide was obtained. The new compounds display very good enzymatic catalytic properties in the oxidation of benzyl alcohols with a rate increase of up to 18500 but only appreciable catalysis for aniline oxidations. Thus, unlike previously studied cyclodextrin ketones, these new amino-acetone-bridged cyclodextrins have high substrate selectivity and also exhibit stereoselectivity in the oxidation of different enantiomers.