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<p>Asymmetric binary catalysis, particularly combining chiral Brønsted acids with Lewis acids, is an emerging strategy in synthetic chemistry. Although a few catalyst combinations exist for stereoselective transformations, their scope is generally limited to pre-organized, activated substrates. Here, we report binary catalysis combining an organosuperacid with bismuth, where the counteranion of chiral <i>N</i>-triflyl phosphoramide acts as a flexible-coordinating ligand. This system demonstrates exceptional reactivity and enantioselectivity in the asymmetric allylation of α-keto thioesters, forming enantio-enriched α-hydroxy thioesters with a tetra-substituted stereogenic carbon center (up to &gt; 99% yield and 97% <i>ee</i>). The success is attributed to bismuth’s flexibility during activation, enhancing also interactions with the thioester-tethered substrate. Integrated experimental, analytical, and computational studies highlight the unique assembly enabled by the chiral Brønsted acid and bismuth salt system.</p>

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Superacid counteranion as flexible-coordinating ligand for asymmetric organo-bismuth catalysis

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年7月2日

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  • Jin Hyun Park,
  • Seok Yeol Yoo,
  • Myoung Hyeon Shin,
  • Sungwook Jeong,
  • Yoonsu Park,
  • Han Yong Bae

摘要

Asymmetric binary catalysis, particularly combining chiral Brønsted acids with Lewis acids, is an emerging strategy in synthetic chemistry. Although a few catalyst combinations exist for stereoselective transformations, their scope is generally limited to pre-organized, activated substrates. Here, we report binary catalysis combining an organosuperacid with bismuth, where the counteranion of chiral N-triflyl phosphoramide acts as a flexible-coordinating ligand. This system demonstrates exceptional reactivity and enantioselectivity in the asymmetric allylation of α-keto thioesters, forming enantio-enriched α-hydroxy thioesters with a tetra-substituted stereogenic carbon center (up to > 99% yield and 97% ee). The success is attributed to bismuth’s flexibility during activation, enhancing also interactions with the thioester-tethered substrate. Integrated experimental, analytical, and computational studies highlight the unique assembly enabled by the chiral Brønsted acid and bismuth salt system.