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Regioselective Synthesis of 5-Trifluoromethylpyrazoles by [3 + 2] Cycloaddition of Nitrile Imines and 2-Bromo-3,3,3-trifluoropropene

Hao Zeng, Xiaojie Fang, Zhiyi Yang, Chuanle Zhu* and Huanfeng Jiang

*School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China, Email:

H. Zeng, X. Fang, Z. Yang, C. Zhu, H. Jiang, J. Org. Chem., 2021, 86, 2810-2819.

DOI: 10.1021/acs.joc.0c02765


A regioselective [3 + 2] cycloaddition of hydrazonyl chlorides with the environmentally friendly and large-tonnage industrial feedstock 2-bromo-3,3,3-trifluoropropene (BTP) provides 5-trifluoromethylpyrazoles. This catalyst-free reaction is operationally simple and features mild conditions, high yields, gram scalability, a broad substrate scope, and high functional group tolerance.

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proposed reaction pathway

in situ generation of hydrazonyl chlorides

Key Words

pyrazoles, 1,3-dipolar cycloaddition

ID: J42-Y2021