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Stereodivergent Synthesis of Allenes with α,β‐Adjacent Central Chiralities Empowered by Synergistic Pd/Cu Catalysis

2023; Wiley; Volume: 62; Issue: 9 Linguagem: Inglês

10.1002/anie.202218146

1521-3773

Ling Zhao, Yicong Luo, Junzhe Xiao, Xiaohong Huo, Shengming Ma, Wanbin Zhang,

Asymmetric Synthesis and Catalysis

The stereodivergent synthesis of allene compounds bearing α,β-adjacent central chiralities has been realized via the Pd/Cu-catalyzed dynamic kinetic asymmetric alkylation of racemic allenylic esters. The matched reactivity of bimetallic catalytic system enables the challenging reaction of racemic aryl-substituted allenylic acetates with sterically crowded aldimine esters smoothly under mild reaction conditions. Various chiral non-natural amino acids bearing a terminal allenyl group are easily synthesized in high yields and with excellent diastereo- and enantioselectivities (up to >20 : 1 dr, >99 % ee). Importantly, all four stereoisomers of the product can be readily accessed by switching the configurations of the two chiral metal catalysts. Furthermore, the easy interconversion between the uncommon η3 -butadienyl palladium intermediate featuring a weak C=C/Pd coordination bond and a stable Csp2 -Pd bond is beneficial for the dynamic kinetic asymmetric transformation process (DyKAT).