Chinese Journal of Organic Chemistry ›› 2024, Vol. 44 ›› Issue (4): 1226-1239.DOI: 10.6023/cjoc202311001 Previous Articles     Next Articles

ARTICLES

二氟甲基溴代腙与β-(N,N-二甲氨基)烯酮/丙烯酸酯/丙烯酰胺的[3+2]环化反应研究

李晓勇, 黄丹凤*(), 周玉秀, 刘小康, 王克虎, 王君娇, 胡雨来*()   

  1. 西北师范大学化学化工学院 兰州 730070
  • 收稿日期:2023-11-01 修回日期:2023-12-11 发布日期:2023-12-28
  • 基金资助:
    国家自然科学基金(22061037); 国家自然科学基金(21861033); 上海恩氟佳科技有限公司资助项目

[3+2] Cyclization of Difluoroacetohydrazonoyl Bromides with β-(N,N-Dimethylamino)enones/Enoates/Enamides

Xiaoyong Li, Danfeng Huang(), Yuxiu Zhou, Xiaokang Liu, Kehu Wang, Junjiao Wang, Yulai Hu()   

  1. College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070
  • Received:2023-11-01 Revised:2023-12-11 Published:2023-12-28
  • Contact: E-mail: huangdf@nwnu.edu.cn; huyl@nwnu.edu.cn
  • Supported by:
    National Natural Science Foundation of China(22061037); National Natural Science Foundation of China(21861033); Shanghai Sinofluoro Chemicals Co., Ltd

A [3+2] cyclization of difluoromethyl nitrile imines generated in situ from difluoroacetohydrazonoyl bromides with β-(N,N-dimethylamino)enones/enoates/enamides in the presence of base is described. The cycloaddition reaction pro- duced the pyrazoline intermediates, from which 3,4-disubstituted-3-difluoromethylpyrazoles were obtained in moderate to good yields via spontaneous elimination of the Me2NH molecule. The reaction is fully regioseclective by the interaction of lowest unoccupied molecular orbital (LUMO) of the 1,3-dipoles and highest occupied molecular orbital (HOMO) of electron-rich alkenes (inverse-electron-demand). This approach expands the types of [3+2] cyclization involved difluoro- methyl nitrile imines, which provides a simple, efficient and novel method for the synthesis of 3-difluoromethylpyrazoles.

Key words: 3-difluoromethylpyrazoles, difluoroacetohydrazonoyl bromides, [3+2] cyclization, regioselectivity