Enantioselectivity Pd-catalyzed allylic substitutions

It seems somewhat puzzling to trace the recent remarkable success in attaining highly enantioselective Pd-catalyzed allylic substitution to the external nucleophilic attack as a key step. In other words, it appears a difficult task to control... 

Phenols have also been used as oxygen nucleophiles in enantioselective Pd-catalyzed allylic substitution reactions. The phenyl ether products 184 and 185 were formed with good enantioselectivity and could be subjected to a subsequent Claisen rearrangement.f " ... 

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