Catalytic Decarboxylative Asymmetric Allylic Alkylation for the Synthesis of Axially Chiral Biaryls

초록

Herein, we report a palladium-catalyzed atroposelective decarboxylative asymmetric allylic alkylation. A chiral palladium complex with a phosphoramidite ligand effectively desymmetrizes biaryls containing cinnamyl carbonate with excellent enantioselectivities. The addition of a catalytic amount of base accelerates the reaction process without loss of enantioselectivity. Cross-over experiment provides mechanistic insight, suggesting that allyl palladium complex primarily dissociates from the original biaryl substrate and deliver allyl species intermolecularly. Analysis of product distribution at various time points indicates that secondary kinetic resolution plays a crucial role in achieving remarkable atroposelectivity. A palladium-catalyzed decarboxylative atroposelective allylic alkylation has been developed. Carbonate substrates undergoes oxidative addition to form a chiral pi-allyl palladium complex, that differentiate two symmetric hydroxyl groups in excellent enantioselectivity.+ image

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