Kinetic Resolution When the Chiral Auxiliary Is Not Enantiomerically Pure: Normal and Abnormal Behavior

Kinetic resolutions with enantioimpure chiral auxiliaries (reagents or catalysts) are considered, and a kinetic treatment for various rate laws is described. A useful parameter, the apparent stereoselectivity factor, is defined and correlated to the enantiomeric excess of the chiral auxiliary. Deviations from the regular laws are possible (asymmetric amplification or depletion). These anomalies have their origins in the same phenomena that cause nonlinear effects in enantioselective catalysis. Asymmetric amplifications have been experimentally observed.