化学学报 ›› 2019, Vol. 77 ›› Issue (9): 866-873.DOI: 10.6023/A19040135 上一篇    下一篇

所属专题: 有机自由基化学

研究通讯

电氧化促进的钯催化的芳烃C(sp 2)—H键氯代反应

杨启亮ab, 王向阳c, 翁信军b, 杨祥b, 徐学涛c, 童晓峰a, 方萍b, 伍新燕a*(), 梅天胜b*()   

  1. a华东理工大学 化学与分子工程学院 结构可控先进功能材料及其制备教育部重点实验室 上海 200237
    b中国科学院上海有机化学研究所 金属有机化学国家重点实验室 分子合成科学卓越中心 上海 200032
    c五邑大学 生物科技与大健康学院 江门 529020
  • 收稿日期:2019-04-19 出版日期:2019-09-15 发布日期:2019-05-08
  • 通讯作者: 伍新燕,梅天胜 E-mail:xinyanwu@ecust.edu.cn;mei7900@sioc.ac.cn
  • 基金资助:
    项目受国家自然科学基金(Nos. 21772222);项目受国家自然科学基金(21821002);广东省教育厅基金资助.(Nos. 2017KTSCX185);广东省教育厅基金资助.(2017KSYS010);广东省教育厅基金资助(2016KCXTD005)

Palladium-Catalyzed ortho-Selective C—H Chlorination of Arenes Using Anodic Oxidation

Yang, Qi-Liangab, Wang, Xiang-Yangc, Weng, Xin-Junb, Yang, Xiangb, Xu, Xue-Taoc, Tong, Xiaofenga, Fang, Pingb, Wu, Xin-Yana*(), Mei, Tian-Shengb*()   

  1. a School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237
    b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032
    c School of Biotechnology and Health Science, Wuyi University, Jiangmen 529020
  • Received:2019-04-19 Online:2019-09-15 Published:2019-05-08
  • Contact: Wu, Xin-Yan,Mei, Tian-Sheng E-mail:xinyanwu@ecust.edu.cn;mei7900@sioc.ac.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China(Nos. 21772222);Project supported by the National Natural Science Foundation of China(21821002);Project supported by the National Natural Science Foundation of China(Nos. 2017KTSCX185);Project supported by the National Natural Science Foundation of China(2017KSYS010);Project supported by the National Natural Science Foundation of China(2016KCXTD005)

芳香族卤代物是非常重要的合成砌块, 卤化反应是有机合成中最基本也是最重要的反应之一. 本工作利用2-(吡啶基)异丙基胺(PIP胺)作为双齿导向基团, 以LiCl作为卤素来源, 通过电化学阳极氧化的策略成功实现了钯催化的芳烃邻位C(sp 2)—H键的氯代反应. 此反应条件官能团耐受性强, 底物适用范围广, 同时能兼容噻吩等杂芳环类底物, 为合成(杂)芳基氯代物提供了一种简洁高效的方法. 该反应可以安全的放大到克级制备, 显示了潜在的工业应用前景. 通过连续的邻位碳氢键溴代和氯代反应还能得到高度复杂的2,5,6-三取代的苯甲酰胺类化合物.

关键词: 有机电合成, 过渡金属催化, 碳氢键活化, 阳极氧化, 氯代反应

Aryl halides are key building blocks in organic synthesis for the construction of valuable natural products, medicinal and agricultural chemicals via transition metal-catalyzed coupling or substitution reactions. Halogenation is one of the most fundamental and important reactions in organic synthesis. Electrochemical transition-metal-catalyzed C—H functionalization has emerged as a powerful tool for molecular synthesis with the prospect of avoiding the use of costly and toxic oxidants or reductants, thereby reducing the footprint of undesirable, toxic byproducts. The palladium-catalyzed electrochemical C—H chlorination of benzamide derivatives directed by PIP amine directing group under divided cells has been demonstrated, in which readily available inorganic halides salts serve as halogen sources. The reaction features a broad substrate scope, high functional group tolerance, and compatibility of thiophene substrates. This reaction could be conducted on a gram scale, which is important for future application. Additionally, the sequential bromination and chlorination of C(sp 2)—H bond constructs highly functionalized aromatic carboxylic acid derivatives. The typical procedure is as follows: The electrolysis was carried out in an H-type divided cell (anion-exchange membrane), with a RVC anode (10 mm×10 mm×12 mm) and a platinum cathode (10 mm×10 mm×0.2 mm). The anodic chamber was charged with Pd(OAc)2 (5.6 mg, 0.025 mmol, 10 mol%) and benzamide derivative (0.25 mmol, 1.0 equiv.) and dissolved in DMF (10 mL). LiCl (847.8 mg, 20.0 mmol) was added in the cathodic chamber and dissolved in water (10 mL). Then the reaction mixture was electrolyzed under a constant current of 5 mA at 90 ℃ until the complete consumption of the starting material as monitored by TLC or 1H NMR. After the reaction, EtOAc (50 mL) was added to dilute the mixture and then washed with water (20 mL×3) and then with brine (20 mL). The organic fraction was dried over Na2SO4 and concentrated. The resulting residue was purified by silica gel flash chromatography to give the chlorination product.

Key words: organic electrosynthesis, transition metal catalysis, C—H activation, anodic oxidation, chlorination