Chinese Journal of Organic Chemistry ›› 2020, Vol. 40 ›› Issue (6): 1618-1624.DOI: 10.6023/cjoc202002009 Previous Articles     Next Articles


王旭才, 陈明, 张威, 张耀都, 任智卉, 关正辉   

  1. 西北大学化学与材料科学学院 合成与天然功能分子教育部重点实验室 西安 710127
  • 收稿日期:2020-02-08 修回日期:2020-03-23 发布日期:2020-03-31
  • 通讯作者: 关正辉
  • 基金资助:

Palladium-Catalyzed 5-exo-trig Hydroamidation of β,γ-Unsaturated Hydrazones for Synthesis of Dihydropyrazoles

Wang Xucai, Chen Ming, Zhang Wei, Zhang Yaodu, Ren Zhihui, Guan Zhenghui   

  1. Key Laboratory of Synthetic and Nature Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science, Northwest University, Xi'an 710127
  • Received:2020-02-08 Revised:2020-03-23 Published:2020-03-31
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 21971204, 216222203, 21702161), the Innovation Capability Support Program of Shaanxi Province (No. 2020TD-022), and the Education Department of Shaanxi Province (No. 19JS064).

Hydroamination reaction is the addition of a N-H unit across the unsaturated C-C bond, which provides a convenient route for the formation of C-N bond. Considerable effort has been directed toward the development of multiple catalytic protocols for the hydroamination reaction in the past decades. Despite appreciable progress in this field, the development of general and practical strategy for the hydroamination of amides remains challenging, because the strong electron-with-drawing substituents (acyl, sulfonyl, or phosphinyl) strongly declined the nucleophilicity of the nitrogen. In this paper, a mild and efficient palladium-catalyzed 5-exo-trig hydroamidation of β,γ-unsaturated hydrazones for the synthesis of dihydropyrazoles has been developed. The reaction employs readily available starting materials, tolerates a wide range of functional groups, and produces a series of valuable dihydropyrazoles in good to high yields (63%~88%) under mild reaction conditions. Furthermore, a gram-scale hydroamidation of 1a afforded the dihydropyrazole 2a in 85% yield. In addition, the deuterium labeling experiment demonstrated that N-H is the hydrogen source in this hydroamidation process.

Key words: palladium-catalyzed, hydroamidation, unsaturated hydrazones, dihydropyrazole, N-heterocycles