Palladium-Catalyzed Decarboxylative Asymmetric Allylic Alkylation of β-ketoesters: An Unusual Counterion Effect

摘要

The formation of quaternary stereogenic centers in an enantioselective fashion remains a significant challenge in the synthesis of complex organic molecules. The palladium-catalyzed asymmetric allylic alkylation (Pd-AAA) has proven to be a highly effective method for the construction of stereogenic quaternary centers. Recently, the palladium-catalyzed decarboxylative asymmetric allylic alkylation (Pd-DAAA) has been developed into a powerful method for the chemo-, regio-, and enantioselective formation of C-C bonds. In many cases, the intramolecular Pd-DAAA reaction has been shown to deliver the desired product in an increased yield and enantiomeric excess, relative to the intermolecular Pd-AAA. The improvement in reactivity and enantioselectivity is particularly noticeable in examples where the new stereogenic center is formed on the nucleophile, which is typically a challenging system for the Pd-AAA.