Nonlinear effects in kinetic resolutions

The impact of nonlinear effects in the asymmetric catalysis of kinetic resolutions is analyzed. It is found with minimal assumptions that the kinetics of homocompetitive reactions should apply generally to kinetic resolutions involving partially resolved catalysts, and this is supported by experimental observations with the Jacobsen hydrolytic kinetic resolution of epoxides. The criterion for a nonlinear effect in asymmetric catalysis, a nonlinear correlation between the enantiomeric excess in a chiral ligand and the product enantiomeric excess obtained from a reaction, is examined. The nonlinear effect idea is found to be generalizable to kinetic resolutions and other reactions by replacing consideration of the product enantiomeric excess with the quantity (k(R)/k(S) - 1)/(k(R)/k(S) + 1), a differential kinetic enantiomeric-enhancement (DKEE). A nonlinear effect may then be defined by a nonlinear correlation between the DKEE and the chiral ligand enantiomeric excess. The application of these ideas to previously reported kinetic resolutions of sulfoxides and to nonlinear effects in the Jacobsen hydrolytic kinetic resolution is described. Relatively small nonlinear effects in kinetic resolutions are sufficient to obtain large asymmetric amplifications.