Construction of Benzoxazine‐linked One‐Dimensional Covalent Organic Frameworks Using the Mannich Reaction

• Published in: Angewandte Chemie International Edition Vol. 63; no. 33; pp. e202403473 - n/a
• Main Authors: Cheng, Cheng, Liu, Yikuan, Sheng, Guan, Jiang, Xinru, Kang, Xing, Jiang, Chao, Liu, Yan, Zhu, Yihan, Cui, Yong
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 12.08.2024; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Aldehydes; Alkylation; Asymmetric catalysis; Benzoxazine; Benzoxazines; Catalysts; Chemistry; Chemistry, Multidisciplinary; Condensation polymerization; Covalence; Covalent organic frameworks; Electrical properties; Electron microscopy; Mannich reaction; Materials synthesis; Optical properties; Organic chemistry; Physical Sciences; Polymers; Science & Technology; Stoichiometry; Benzoxazine; Covalent organic frameworks; TOPOLOGY; CATALYSIS; POLYMERS; DESIGN; NANOSHEETS; ADSORPTION; Asymmetric catalysis; Materials synthesis; SINGLE-CRYSTAL; Mannich reaction; CHEMISTRY; SEPARATION
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202403473

Covalent polymerization of organic molecules into crystalline one‐dimensional (1D) polymers is effective for achieving desired thermal, optical, and electrical properties, yet it remains a persistent synthetic challenge for their inherent tendency to adopt amorphous or semicrystalline phases. Here we report a strategy to synthesize crystalline 1D covalent organic frameworks (COFs) composing quasi‐conjugated chains with benzoxazine linkages via the one‐pot Mannich reaction. Through [4+2] and [2+2] type Mannich condensation reactions, we fabricated stoichiometric and sub‐stoichiometric 1D covalent polymeric chains, respectively, using doubly and singly linked benzoxazine rings. The validity of their crystal structures has been directly visualized through state‐of‐the‐art cryogenic low‐dose electron microscopy techniques. Post‐synthetic functionalizations of them with a chiral MacMillan catalyst produce crystalline organic photocatalysts that demonstrated excellent catalytic and recyclable performance in light‐driven asymmetric alkylation of aldehydes, affording up to 94 % enantiomeric excess Two crystalline 1D benzoxazine‐linked covalent organic polymers have been successfully synthesized in a one‐pot Mannich reaction. The validity of their crystal structures has been directly visualized through state‐of‐the‐art cryogenic low‐dose electron microscopy techniques.