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<p>In this study, a new chiral polymer incorporating cinchonine- and cinchonidine-based squaramide units in its main chain has been successfully synthesized and evaluated as asymmetric organocatalysts. The novelty of this work lies in the integration of dual cinchonine- and cinchonidine cinchona moieties within the squaramide framework, offering enhanced chiral environments and hydrogen-bonding capabilities for asymmetric catalysis. Cinchonine- and cinchonidine-based chiral squaramide monomers bearing olefinic double bonds were first designed and synthesized, followed by the Mizoroki–Heck coupling polymerization reaction using various diiodo linkers to yield the desired polymers with controlled microenvironment. The resulting polymeric catalysts exhibited remarkable catalytic activity (upto 99% yield) and enantioselectivity (upto 94% ee, 75:1 dr) in model asymmetric reactions, demonstrating the significant role of the cinchonine- and cinchonidine cinchona-derived units and solvent polarity on the reaction outcome. Importantly, due to their insolubility in common organic solvents, the polymeric catalysts could be easily recovered and reused multiple times without noticeable loss of performance. These findings establish a new strategy for developing recyclable chiral polymeric catalysts based on cinchonine- and cinchonidine cinchona–squaramide frameworks, combining high catalytic efficiency, robust stability, and excellent reusability for sustainable asymmetric synthesis.</p>

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Cinchonine- and Cinchonidine-Derived Chiral Squaramide Polymers: Synthesis and Application in Asymmetric Catalysis

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Mohammad Shahid Ullah,
  • Mohammad Farhadur Rahman,
  • Shinichi Itsuno

摘要

In this study, a new chiral polymer incorporating cinchonine- and cinchonidine-based squaramide units in its main chain has been successfully synthesized and evaluated as asymmetric organocatalysts. The novelty of this work lies in the integration of dual cinchonine- and cinchonidine cinchona moieties within the squaramide framework, offering enhanced chiral environments and hydrogen-bonding capabilities for asymmetric catalysis. Cinchonine- and cinchonidine-based chiral squaramide monomers bearing olefinic double bonds were first designed and synthesized, followed by the Mizoroki–Heck coupling polymerization reaction using various diiodo linkers to yield the desired polymers with controlled microenvironment. The resulting polymeric catalysts exhibited remarkable catalytic activity (upto 99% yield) and enantioselectivity (upto 94% ee, 75:1 dr) in model asymmetric reactions, demonstrating the significant role of the cinchonine- and cinchonidine cinchona-derived units and solvent polarity on the reaction outcome. Importantly, due to their insolubility in common organic solvents, the polymeric catalysts could be easily recovered and reused multiple times without noticeable loss of performance. These findings establish a new strategy for developing recyclable chiral polymeric catalysts based on cinchonine- and cinchonidine cinchona–squaramide frameworks, combining high catalytic efficiency, robust stability, and excellent reusability for sustainable asymmetric synthesis.