Application of the Term "Relative Enantioselectivity" as Useful Measure for Comparison of Chiral Catalysts, Demonstrated on Asymmetric Hydrogenation of Amino Acid Precursors

Article abstract of DOI:10.1016/S0957-4166(00)86082-6

The application of the quotient "relative enantioselectivity" Q = q/q' in which q and q' are enantiomeric ratios R/S (or S/R) for two comparable cases of asymmetric synthesis experiments is recommended for comparison of two or more catalysts or other variables like solvents, substrates and cofactors.The importance of this term Q lies in the possibility to form and compare values of enantioselectivity over the whole range from 99.9percent ee (R) to 99.9percent ee (S) in a mathematically correct way and is demonstrated on multiple examples of asymmetric hydrogenation of partly new N-acyl-dehydroamino acid derivatives with a couple of catalysts BF4 1 and BF4 2.Interesting inversions of Q could be discovered for changes of the type of substrate and in dependence of the polarity of solvents.