CAN THE PRESENCE OF CHEMICALLY INERT SPECIES MODIFY THE FACE SELECTIVITY IN ASYMMETRIC INDUCTION BY CYCLODEXTRINS

Reduction of beta-cyclodextrin (beta-CD) aromatic ketone (acetophenone and acetonaphthones) inclusion compounds were carried out in the pres ence of a large number of chemically inert species as potential co-gue sts. In several cases, it was observed that stoichiometric molar ratio s of these compounds to ketone significantly modify the chiral inducti on yielding the inverted alcohol enantiomer and increasing the face se lectivity. The results were found to depend strongly on the respective structure and shape of both the ketone and the additive, and on the m olar ratio of beta-CD:ketone:third compound. These observations sugges t the formation of a three-component inclusion complex in which the ge ometry of binding of the substrate and its mobility are changed with r espect to the binary system.