Kinetic implications of nonlinear effects in asymmetric synthesis

Observation of a conversion-dependent enantioselectivity in asymmetric reac tions with nonenantiopure catalysts or reagents may be diagnostic of kineti cally complex behavior. This paper shows how reaction simulations based on parameters derived from initial enantioselectivity data provide an extensio n of the Kagan MLn models as powerful mechanistic tools in asymmetric synth esis. This approach is illustrated for an example of a stoichiometric reduc tion of aralkyl ketones with chiral borane reagents and is also discussed f or several cases of catalytic reactions.