Acta Chimica Sinica ›› 2021, Vol. 79 ›› Issue (6): 751-754.DOI: 10.6023/A21050200 Previous Articles     Next Articles

Communication

无金属条件下的肉桂酸类和酰胺的脱羧氧化偶联反应构建碳-碳键

卢小彪a, 肖茜a, 万常峰a,*(), 汪志勇b, 刘晋彪c   

  1. a 江西师范大学化学化工学院 南昌 330022
    b 中国科学技术大学微尺度物质科学国家实验室 合肥 230026)
    c 江西理工大学化学化工学院 赣州 341000
  • 投稿日期:2021-05-10 发布日期:2021-05-28
  • 通讯作者: 万常峰
  • 基金资助:
    国家自然科学基金(21402068); 国家自然科学基金(21502075)

Direct C—C Bond Formation through Decarboxylative Oxidative Cross-Coupling of Cinnamic Acids with Amides under Metal-Free Condition

Xiaobiao Lua, Xi Xiaoa, Changfeng Wana(), Zhiyong Wangb, Jinbiao Liuc   

  1. a College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China
    b Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
    c School of Chemistry and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
  • Received:2021-05-10 Published:2021-05-28
  • Contact: Changfeng Wan
  • Supported by:
    National Natural Science Foundation of China(21402068); National Natural Science Foundation of China(21502075)

Traditional coupling reactions generally employ metal organic compounds, boron reagents or halogenated compounds as reaction starting materials under the condition of noble metal-catalyst, such as Suzuki reaction and Heck reaction. Although these reactions have been widely used in synthesis, due to the need for prefunctionalization of reactants, they do not have high atomic economy and step economy. Especially for some substrates that are not easy to introduce functional groups, the application of such reactions is limited. In recent years, with the development of organic chemistry, direct C―H bond functionalization has become a research hotspot in organic synthesis. This kind of reaction can overcome the deficiency of traditional coupling reaction, making this kind of reaction more attractive. Amides are very important compounds, which are widely found in natural products and drugs. Through literature investigation, it was found that some functionalization reactions of C(sp3)―H bond adjacent to the nitrogen atom of amides had already reported. Due to the facile synthesis, stability and low toxicity of cinnamic acid compounds, they are also used in organic synthesis to obtain desired product. When we studied the decarboxylation reaction of cinnamic acid compounds, we found that the decarboxylative coupling product of cinnamic acid with amides could be obtained by using amide as solvent, tert-butyl hydroperoxide (TBHP) as oxidant and cinnamic acid as starting material without the use of metal catalyst. The reaction mechanism was also proposed. First, homolysis of tert-butyl alcohol peroxide generated tertiary butyl oxygen free radical and hydroxyl free radicals, the oxidation of C(sp3)―H bonds adjacent to the nitrogen atom of N,N-dimethylacetamide offered carbon free radical, which adds to the α-position of the double bond of cinnamic acid to produce intermediate A. A hydroxyl radical, generated from homolysis of TBHP, then combined with A to generate B, and B was further oxidized to C. Finally, C decarboxylated easily to generate the desired product.

Key words: C―H bond functionalization, decarboxylation, oxidative cross-coupling, amide