Cycloaddition of Trifluoroacetaldehyde N-Triftosylhydrazone (TFHZ-Tfs) with Alkynes for Synthesizing 3-Trifluoromethylpyrazoles
Hongwei Wang, Yongquan Ning, Yue Sun, Paramasivam Sivaguru and Xihe Bi*
*Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of Chemistry, Northeast Normal University, Changchun 130024, China, Email: bixh507nenu.edu.cn
H. Wang, Y. Ning, Y. Sun, P. Sivaguru, X. Bi, Org. Lett., 2020, 22, 2012-2016.
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An operationally simple, transition-metal-free [3 + 2] cycloaddition between trifluoroacetaldehyde N-triftosylhydrazone (TFHZ-Tfs) and alkynes provides 3-trifluoromethylpyrazoles in very good yields with broad substrate scope, including aryl, heteroaryl, and alkyl terminal alkynes, and electron-deficient internal alkynes.
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Pyrazoles, 1,3-dipolar cycloaddition