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<p>Schiff bases, despite their structural versatility and broad applications, have remained elusive as acyclic atropisomers due to synthetic challenges. Herein, we report a palladium-catalyzed asymmetric <i>N</i>-allylation of diarylmethanimines with allylic precursors, enabling the construction of acyclic Schiff base atropisomers bearing C–C axes. Crucially, dynamic ligand exchange between the imine substrates and the palladium pre-catalyst drives its evolution from a less active to a more reactive species. This self-optimizing system leads to a unique time-dependent enhancement of enantioselectivity up to 96% ee. Experimental and density functional theory studies reveal that substrate-induced reorganization of the catalytic system optimizes the reaction pathway, leading to high yields (up to 83%) and absolute <i>Z</i> stereoselectivity. The method exhibits remarkable functional group tolerance and scalability, and its utility is demonstrated through diverse transformations. This work provides efficient access to previously inaccessible atropisomeric scaffolds and establishes a paradigm of substrate-guided catalyst evolution for asymmetric catalysis.</p>

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Dynamic palladium catalysis enables chiral amplification toward acyclic Schiff base atropisomers

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月20日

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  • Qi Liu,
  • Jun Gu,
  • Shu-Yun Cui,
  • Linghua Tan,
  • Ying He

摘要

Schiff bases, despite their structural versatility and broad applications, have remained elusive as acyclic atropisomers due to synthetic challenges. Herein, we report a palladium-catalyzed asymmetric N-allylation of diarylmethanimines with allylic precursors, enabling the construction of acyclic Schiff base atropisomers bearing C–C axes. Crucially, dynamic ligand exchange between the imine substrates and the palladium pre-catalyst drives its evolution from a less active to a more reactive species. This self-optimizing system leads to a unique time-dependent enhancement of enantioselectivity up to 96% ee. Experimental and density functional theory studies reveal that substrate-induced reorganization of the catalytic system optimizes the reaction pathway, leading to high yields (up to 83%) and absolute Z stereoselectivity. The method exhibits remarkable functional group tolerance and scalability, and its utility is demonstrated through diverse transformations. This work provides efficient access to previously inaccessible atropisomeric scaffolds and establishes a paradigm of substrate-guided catalyst evolution for asymmetric catalysis.