Asymmetric reduction of prochiral inclusion complex in aqueous media

In the formation of an inclusion compound, the interaction of both ionic and hydrogen bonds were shown to be involved in the asymmetric reduction of a keto acid in the presence of 6-deoxy-6-amino-β-cyclodextrin with NaBH4 in an aqueous buffer solution. Furthermore, multiple interactions were elucidated and the enatioface differentiating reduction was induced in the concerted interactions. Asymmetric reduction of a keto acid in the presence of newly prepared alkylamino-substituted β-cyclodextrin (CD) gave a higher optical yield. There should be a steric effect by a substituent group on the CD to form the conformation favoured by the multi-interaction between host and guest A mechanistic scheme for the enatioface differentiating attack of a reducing reagent on the included substrate is suggested.