Nonlinear Effects in Rh-Catalyzed Asymmetric Olefin Hydrogenation

Significance

This is a very nice mechanistic and theoretical study aimed at further illumination of the nonlinear effects commonly seen in rhodium-catalyzed hydrogenations. Chiral catalysts with low optical purity (i.e. 80% ee) can be combined with a racemic catalyst, and high enantioselectivity for the hydrogenation can still be observed (>90% ee). While many rate constants, homo- versus hetero-combinations of catalysts and the ratios of this combination make this a complex system to be fully understood, the authors have presented a few ideas on the important factors influencing the nonlinear effect.