Copper-Mediated Domino Cyclization/Trifluoromethylation/Deprotection with TMSCF₃: Synthesis of 4-(Trifluoromethyl)pyrazoles

Quande Wang, Lisi He, Kin Keung Li and Gavin Chit Tsui*

*Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China, Email: gctsuicuhk.edu.hk

Q. Wang, L. He, K. K. Li, G. C. Tsui, Org. Lett., 2017, 19, 658-661.

DOI: 10.1021/acs.orglett.6b03822

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Abstract

A copper-mediated remarkable domino sequence of cyclization, trifluoromethylation, and detosylation provides 4-(trifluoromethyl)pyrazoles from readily accessible α,β-alkynic tosylhydrazones and commercially available trifluoromethyltrimethylsilane as the CF₃ source. The reaction conditions are mild and convenient with good functional group compatibility, at room temperature in air.

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Key Words

pyrazoles, trifluoromethylation, oxygen

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ID: J54-Y2017