Resolving Isotopically Chiral Alcohols

Abstract

Autocatalytic reactions, which are accelerated by their own product, can amplify small imbalances in the chiral distribution of starting materials. A particularly effective system is the alkylation of certain aldehydes by diisopropyl zinc, which becomes increasingly stereoselective as the chiral alkoxide product coordinates to unreacted zinc centers. Kawasaki et al. (p. [492][1], published online 26 March) show that the sense of enantioselection in this system can be influenced by a factor as subtle as chirality in an alcohol that arises only because two positions differ in having 12C and 13C atoms. Isotopically chiral ligands were carefully prepared by using methods that would avoid chiral contaminants, and each led to a distinct enantiomer with enantiomeric excesses exceeding 90%. [1]: /lookup/doi/10.1126/science.1170322