Chinese Journal of Organic Chemistry ›› 2022, Vol. 42 ›› Issue (12): 4292-4299.DOI: 10.6023/cjoc202211002 Previous Articles     Next Articles



穆思宇a, 李红霞a, 伍智林b, 彭俊梅a,*(), 陈锦杨b, 何卫民b,*()   

  1. a 南华大学药学院 湖南衡阳 421001
    b 南华大学化学化工学院 湖南衡阳 421001
  • 收稿日期:2022-11-01 修回日期:2022-11-20 发布日期:2022-11-28
  • 通讯作者: 彭俊梅, 何卫民
  • 基金资助:
    湖南省自然科学基金(2021JJ40429); 湖南省教育厅科学研究基金(19B501)

Electrocatalytic Three-Component Synthesis of 4-Bromopyrazoles from Acetylacetone, Hydrazine and Diethyl Bromomalonate

Siyu Mua, Hongxia Lia, Zhilin Wub, Junmei Penga(), Jinyang Chenb, Weimin Heb()   

  1. a School of Pharmaceutical Science, University of South China, Hengyang, Hunan 421001
    b School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001
  • Received:2022-11-01 Revised:2022-11-20 Published:2022-11-28
  • Contact: Junmei Peng, Weimin He
  • Supported by:
    Natural Science Foundation of Hunan Province(2021JJ40429); Research Foundation of Education Bureau of Hunan Province(19B501)

Pyrazoles are the most important five-membered N-heterocycles as they are present in many natural products and synthetic drugs. Among various pyrazole derivatives, 4-bromopyrazoles have attracted great attention because they not only display significant biological activities and physicochemical properties but also serve as valuable synthons in organic chemistry. In this manuscript, an efficient and eco-friendly method for the synthesis of various 4-bromopyrazoles through three- component reaction of hydrazine, acetylacetone and 2-bromomalonate was reported and the proposal reaction mechanism was revealed. According to the mechanism, hydrazine reacts with acetylacetone to afford pyrazole firstly, which then converts to 4-bromopyrazole through bromination. This method could also be well applicable for the bromination of other heterocyclic compounds. Given the high oxidation state of diethyl 2-bromomalonate, the peroxidation can be avoided through the electrolysis process, thus the excess amount of brominating agent was not be required.

Key words: electro-organic synthesis, multicomponent reaction, bromination reaction, 4-bromopyrazole derivatives