Synergistic catalysis for stereocontrol of prochiral nucleophiles in palladium-catalyzed asymmetric allylic substitution

In contrast to the stereocontrol of the stereocenter at the allyl unit, the asymmetric induction of prochiral nucleophiles remains a challenge in Pd-catalyzed asymmetric allylic substitutions due to the remote distance between the chiral catalyst and the stereocenter established at prochiral nucleophile. Much effort has been devoted to solving this challenge through the elaborate design of chiral ligands. Recently, synergistic catalysis has gained increasing attention owing to its potential advantages over the traditional single palladium catalysis, such as improvement of reactivity and selectivity. This strategy, including bimetallic catalysis and Pd/organocatalysis, not only broadens the scope of prochiral nucleophiles, but also provides a simple and unified method for the stereocontrol of prochiral nucleophiles. This review summarizes the brief history and advances in this field.