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  • Synthesis of Chiral Covalen...
    Li, Fei; Kan, Jing‐Lan; Yao, Bing‐Jian; Dong, Yu‐Bin

    Angewandte Chemie International Edition, June 20, 2022, Letnik: 61, Številka: 25
    Journal Article

    A general and efficient organocatalytic asymmetric polymerization approach for the synthesis of chiral covalent organic frameworks (CCOFs) has been developed. With a chiral 2‐methylpyrrolidine catalyst, a series of tris(N‐salicylideneamine)‐derived β‐ketoenamine‐CCOFs are directly constructed from prochiral aldehyde‐ and primary amine‐monomers. The adopted aminocatalytic asymmetric Schiff‐base condensation herein is performed under ambient conditions with clear green synthetic advantages over the conventional acid‐catalysed solvothermal methods. The obtained β‐ketoenamine‐CCOFs can be further metalated by a solid‐state coordination approach, and the resulting CuII@CCOFs can highly promote an asymmetric A3‐coupling reaction. Specifically, a CuII@CCOF@chitosan aerogel was fabricated as a highly efficient fixed‐bed model reactor for scaled‐up catalysis. The concept of aminocatalytic asymmetric polymerization might open a new way for constructing the CCOFs via asymmetric organocatalysis. A new and general organocatalytic asymmetric polymerization approach for the chiral covalent organic framework (CCOF) synthesis under ambient conditions is presented. The metalated CCOF can be further shaped into a fixed‐bed reactor by incorporation with ecofriendly and low‐cost chitosan to realize the scaled‐up catalytic asymmetric A3‐coupling reaction in a green and facile way.