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Anthraquinone-based covalent organic framework as a recyclable direct hydrogen atom transfer photocatalyst for C–H functionalization
Chemical Science ( IF 7.6 ) Pub Date : 2024-02-28 , DOI: 10.1039/d4sc00241e
Zitong Wang 1 , Pierce Yeary 1 , Yingjie Fan 1 , Wenbin Lin 1
Affiliation  

Photocatalytic direct hydrogen atom transfer (d-HAT) is a synthetically important strategy to convert C–H bonds to useful C–X bonds. Herein we report the synthesis of an anthraquinone-based two-dimensional covalent organic framework, DAAQ-COF, as a recyclable d-HAT photocatalyst for C–H functionalization. Powder X-ray diffraction, N2 sorption isotherms, solid-state NMR spectra, infrared spectra, and thermogravimetric analysis characterized DAAQ-COF as a crystalline, porous COF with a stable ketoenamine linkage and strong absorption in the visible region. Under visible light irradiation, DAAQ-COF is photo-excited to cleave C(sp3)–H or C(sp2)–H bonds via HAT to generate reactive carbon radicals, which add to different radical acceptors to achieve C–N or C–C coupling reactions. DAAQ-COF is easily recovered from the reaction mixture via centrifugation or filtration and used in six consecutive reaction runs without any decrease in catalytic efficiency. The ease of catalyst separation allows sequential conversion of the C–N coupling intermediate to synthetically useful amide, ester, or thioester products. Photophysical and isotope labelling experiments support the d-HAT mechanism of DAAQ-COF-catalyzed C–H bond functionalization.

中文翻译:


基于蒽醌的共价有机骨架作为可回收的直接氢原子转移光催化剂用于C-H功能化



光催化直接氢原子转移(d-HAT)是将 C-H 键转化为有用的 C-X 键的综合重要策略。在此,我们报道了基于蒽醌的二维共价有机框架DAAQ-COF的合成,作为可回收的 d-HAT 光催化剂,用于 C-H 官能化。粉末X射线衍射、N 2吸附等温线、固态NMR光谱、红外光谱和热重分析将DAAQ-COF表征为结晶、多孔COF,具有稳定的酮烯胺键和在可见光区域的强吸收。在可见光照射下, DAAQ-COF受到光激发,通过HAT裂解C(sp 3 )–H或C(sp 2 )–H键,产生活性碳自由基,与不同的自由基受体加成,得到C–N或C-C 偶联反应。 DAAQ-COF可以通过离心或过滤轻松从反应混合物中回收,并用于六次连续反应运行,而不会降低催化效率。催化剂分离的简便性使得 C-N 偶联中间体能够顺序转化为合成有用的酰胺、酯或硫酯产品。光物理和同位素标记实验支持DAAQ-COF催化 C-H 键功能化的 d-HAT 机制。
更新日期:2024-02-28
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