Synthesis of Chiral Covalent Organic Frameworks via Asymmetric Organocatalysis for Heterogeneous Asymmetric Catalysis

• Published in: Angewandte Chemie International Edition Vol. 61; no. 25; pp. e202115044 - n/a
• Main Authors: Li, Fei, Kan, Jing‐Lan, Yao, Bing‐Jian, Dong, Yu‐Bin
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 20.06.2022; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Aerogels; Aldehydes; Asymmetric A3-Coupling Reaction; Asymmetric Organocatalysis; Asymmetry; Catalysis; Catalysts; Chemical synthesis; Chemistry; Chemistry, Multidisciplinary; Chiral Covalent Organic Framework; Chitosan; Metalation; Monomers; Physical Sciences; Polymerization; Science & Technology; β-Ketoenamine; beta-Ketoenamine; Chiral Covalent Organic Framework; STABILITY; CONSTRUCTION; Asymmetric A-Coupling Reaction; Metalation; Asymmetric Organocatalysis; CRYSTALLINE; ADSORPTION; β-Ketoenamine; Asymmetric A3-Coupling Reaction
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202115044

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.