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可见光触发2-异氰基联苯与二氟溴乙酸酯自催化二氟甲基化/环化串联反应

彭佳a,#, 杨云a,#, 蔡迎丽a, 易荣楠b,*, 姜东方c, 唐裕才d, e, 吴超a,*, 叶龙武a,*, 何卫民a,*   

  1. a南华大学化学化工学院 衡阳 421001;
    b湖南警察学院食药环及毒品检验技术湖南省普通高等学校重点实验室 长沙 410138;
    c长沙医学院功能核酸基础与临床湖南省普通高校重点实验室 长沙 410219;
    d湖南文理学院化学与材料工程学院 常德 415000;
    e南京林业大学化学工程学院 南京 210037
  • 投稿日期:2026-07-23
  • 作者简介:#共同第一作者.
  • 基金资助:
    湖南省自然科学基金(No. 2026JJ90135), 湖南省科技创新计划(No. 2023RC4004)资助项目, 湖南省教育厅科学研究项目(No. 25A0703, No.23B0411), 长沙市自然科学基金 (No.104872).

Visible-Light-Triggered Self-Catalyzed Tandem Difluoromethylation/Cyclization of 2-Isocyanobiphenyls with Alkyl Bromodifluoroacetates

Jia Penga,#, Yun Yanga,#, Ying-Li Caia, Rong-Nan Yib,*, Dong-Fang Jiangc, Yu-Cai Tangd, e, Chao Wua,*, Long-Wu Yea,*, Wei-Min Hea,*   

  1. aSchool of Chemistry and Chemical Engineering, University of South China, Hengyang 421001;
    bKey Laboratory of Food & Environment & Drug Monitoring and Testing of Universities in Hunan Province, Hunan Police Academy, Changsha 410138;
    cHunan Provincial University Key Laboratory of the Fundamental and Clinical Research on Functional Nucleic Acid, Changsha Medical University, Changsha 410219;
    dCollege of Chemistry and Materials Engineering, Hunan University of Arts and Science, Changde 415000;
    eSchool of Chemical Engineering, Nanjing Forestry University, Nanjing 210037
  • Received:2026-07-23
  • Contact: *E-mail: yrn@hnu.edu.cn; chwu_chem@usc.edu.cn; longwuye@xmu.edu.cn; weiminhe@usc.edu.cn
  • About author:#These authors contributed equally to this work.
  • Supported by:
    Hunan Provincial Natural Science Foundation (No. 2026JJ90135), the Science and Technology Innovation Program of Hunan Province (No. 2023RC4004), the Scientific Research Fund of Hunan Provincial Education Department (No. 25A0703 and No.23B0411) and the Changsha Natural Science Foundation (No.104872)

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可见光催化将光能转化为化学能, 在温和条件下实现化学键的断裂与重组, 完成诸多传统热化学路径难以驱动的转化, 具有环境友好及官能团耐受性高等优点, 已在复杂功能分子合成中展现出显著的催化效率和工业应用潜力. 然而, 现有方法多依赖外源光催化剂, 存在回收困难或活性不足等问题. 为此, 本文以2-异氰基联苯为底物、二氟溴乙酸酯为烷氧基羰基二氟甲基化试剂, 利用底物和产物自身充当光敏剂, 发展了一种无需外源光敏剂及添加剂的可见光触发自催化烷氧基羰基二氟甲基化/环化串联反应, 以68%-82%的分离收率获得20种6-烷氧基羰基二氟甲基菲啶化合物, 并可实现克级规模制备. 该策略不仅简化了反应体系并降低了分离难度, 同时具有操作简便和底物适用范围广等优势, 为6-烷氧基羰基二氟甲基菲啶类化合物的绿色可持续合成提供了新路径, 高度契合绿色化学的原子经济性和步骤经济性原则.

关键词: 可见光催化, 自催化, 二氟甲基化反应, 2-异氰基联苯, 菲啶

The introduction of difluoromethylated units, particularly the alkoxycarbonyl difluoromethyl (CF2CO2R) group, into organic molecules has garnered substantial interest due to its capacity to enhance metabolic stability, lipophilicity, and bioavailability, while also serving as a versatile handle for downstream diversification. Phenanthridine derivatives represent a privileged class of N-heterocycles widely prevalent in natural products, pharmaceuticals, and functional materials. Although visible-light photocatalysis has emerged as a powerful tool for constructing such fluorinated scaffolds, the majority of current protocols rely on external photosensitizers or stoichiometric additives, which raise concerns regarding cost, recyclability, and environmental sustainability.
We herein report a visible-light-triggered self-catalyzed tandem difluoromethylation/cyclization of 2-isocyanobiphenyls with alkyl bromodifluoroacetates under exogenous photocatalyst- and additive-free conditions. Under optimized conditions (415 nm LED irradiation, THF, 4 Å molecular sieves, argon, room temperature), a broad range of 2-isocyanobiphenyls bearing either electron-donating or electron-withdrawing groups were efficiently converted into the corresponding 6-alkoxycarbonyl difluoromethyl phenanthridines in 68%-82% yields (20 examples). The reaction exhibits excellent functional-group tolerance, accommodating halogens, trifluoromethyl, acetyl, ester, methoxy, and other valuable functionalities, and is also applicable to disubstituted substrates. Gram-scale synthesis was achieved with 65% isolated yield, underscoring the practical utility of this approach.
Mechanistic investigations revealed that the process is initiated by energy transfer from the photoexcited substrate or product to the bromodifluoroacetate, which induces homolytic C-Br bond cleavage to generate an alkoxycarbonyl difluoromethyl radical. This radical then undergoes regioselective addition to the isocyanide moiety, followed by intramolecular cyclization and oxidative dehydrogenation to afford the final product. This self-catalyzed strategy not only simplifies the reaction system and facilitates product isolation but also obviates the need for exogenous photocatalysts and additives, thereby aligning with green chemistry principles and offering a sustainable, atom-economical route to valuable fluorinated phenanthridines.

Key words: visible-light photocatalysis, self-catalysis, difluoromethylation reaction, 2-isocyanobiphenyls, phenanthridine