Selective nucleophilic aromatic substitution of 2-(polyfluorophenyl)-4H-chromen-4-ones with pyrazole

•The base-promoted SNAr reactions of polyfluoroflavones with pyrazole.•The proposed mechanism for sequential substitution in reaction of pentafluoroflavone with pyrazole.•The selective synthesis of mono- and per(pyrazol-1-yl)-substituted flavones. The formation of various fluorine atoms substitution...

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Bibliographic Details
Published in:Journal of fluorine chemistry 2022-11, Vol.263, p.110034, Article 110034
Main Authors: Panova, Mariya A., Shcherbakov, Konstantin V., Burgart, Yanina V., Saloutin, Victor I.
Format: Article
Language:English
Subjects:
Nucleophilic aromatic substitution
Polyfluoroflavones
Pyrazole
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Summary:•The base-promoted SNAr reactions of polyfluoroflavones with pyrazole.•The proposed mechanism for sequential substitution in reaction of pentafluoroflavone with pyrazole.•The selective synthesis of mono- and per(pyrazol-1-yl)-substituted flavones. The formation of various fluorine atoms substitution products in Cs2CO3-promoted SNAr reactions of 2-(polyfluoroaryl)-4H-chromen-4-ones with pyrazole in refluxing MeCN was shown. Selective synthesis of mono(1H-pyrazol-1-yl)- and per(1H-pyrazol-1-yl)flavones was performed in the presence of NaOBut at room temperature using different pyrazole and base equivalents. A mechanism for fluorine atoms substitution in 2-(pentafluorophenyl)-4H-chromen-4-one by sodium pyrazolide was proposed. The structures of pyrazolyl-substituted flavones were established based on the combined analysis of NMR and XRD data. [Display omitted]
ISSN:0022-1139
1873-3328
DOI:10.1016/j.jfluchem.2022.110034