Meng Fancheng, Bi Shuai, Sun Zuobang, Wu Dongqing, Zhang Fan
School of Chemistry and Chemical Engineering; State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
Angew Chem Int Ed Engl. 2022 Nov 2;61(44):e202210447. doi: 10.1002/anie.202210447. Epub 2022 Oct 5.
Knoevenagel condensation is a powerful tool for the construction of vinylene-linked covalent organic frameworks. Herein, we established a concise approach to vinylene-linked COFs by Knoevenagel condensation at the multi-methyl groups of a pyridine ring through in situ formation of an N-acyl pyridinium cation in the presence of various acylating reagents. Following this strategy, two vinylene-linked COFs were constructed using 2,4,6-trimethylpyridine and multi-aldehyde-substituted aromatic derivatives as monomers. The resultant COFs are highly crystalline and assembled into hexagonal lattices with specific surface areas as large as 1915 m g (vs. 1972 m g of the theoretical value). The stable and abundant pyridine-decorated regular nanochannels within the COFs allow for catalyzing the esterification of several pharmaceutical intermediates with distinct spatially confined selectivity and recyclability, representing an environmentally friendly catalytic organic transformation.
克诺文纳格尔缩合反应是构建亚乙烯基连接的共价有机框架的有力工具。在此，我们通过在各种酰化试剂存在下原位形成N-酰基吡啶鎓阳离子，在吡啶环的多个甲基上进行克诺文纳格尔缩合反应，建立了一种简洁的方法来制备亚乙烯基连接的共价有机框架。按照这种策略，使用2,4,6-三甲基吡啶和多醛取代的芳香族衍生物作为单体构建了两种亚乙烯基连接的共价有机框架。所得的共价有机框架具有高度结晶性，并组装成六方晶格，比表面积高达1915 m²/g（理论值为1972 m²/g）。共价有机框架内稳定且丰富的吡啶修饰的规则纳米通道能够催化几种药物中间体的酯化反应，具有独特的空间受限选择性和可回收性，代表了一种环境友好的催化有机转化过程。
