Pd-catalyzed direct arylation of phenylpyrazole: Synthesis of fipronil derivatives with aryl boronic acids promoted by a stoichiometric amount of NIS

The palladium-catalyzed direct arylation of phenylpyrazole with aryl boronic acid promoted by a stoichiometric amount of NIS has been reported. Several phenyl pyrazoles, especially for those with trifluoromethyl groups, can participate in the reaction, providing a series of fipronil derivatives of 4-aryl-phenylpyrazole with potential bioactivity in moderate to good yields. All the compounds were characterized by 1H NMR, 13C NMR and HRMS spectroscopic techniques.

Pd-catalyzed arylation of phenylpyrazole (1a–c) with arylboronic acid to afford a series of fipronil derivatives.Figure optionsDownload as PowerPoint slideHighlights
► The direct arylation of phenylpyrazole has been developed using PdCl2(PPh3)2 as catalyst.
► Several fipronil derivatives were prepared in moderate to good yields by this method.
► The method provides a direct route to afford trifluoromethyl-containing 4-aryl-phenylpyrazoles.
► The compounds were identified by 1H NMR, 13C NMR and HRMS spectroscopic techniques.