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Switching N-Alkylation Regioselectivity of Trifluoromethylated Pyrazoles Guided by Functional Group Tuning
Yulia O Edilova1, Yulia S Kudyakova1, Ekaterina A Osipova1,2
1Postovsky Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, Yekaterinburg 620137, Russia.
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The similar properties of the nitrogen atoms in azole ring complicate the regioselective N-functionalization of pyrazoles. This work demonstrates the role of the hydrazone substituent in the control of the alkylation selectivity of (trifluoromethyl)pyrazoles. Reaction conditions for the synthesis of 3- and 5-(trifluoromethyl)pyrazoles were developed, and all types of regioisomers formed under the alkylation of bis-pyrazolyl NH-ketazine were isolated. The structures of the synthesized compounds were confirmed by NMR spectroscopy and XRD data.
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