Asymmetric Protonation of Enolates

Abstract

Efficient chiral proton sources have long been the organic chemist's dream. With the lactam 1 based on Kemp's tricarboxylic acid, cyclic enolates have now been protonated with an enantiomeric excess (ee) of up to 91%. The reason for the high ee values is the asymmetric microenvironment of the acidic NH group.