Metal-free electrophilic fluorination, promoted by Selectfluor, of pyrazoles with methylene groups (CH2X), in which X = OH, OMe, F, N3, and NHMe at the C-4 position furnished the 4-fluoro-pyrazole products from unexpected C–C bond cleavage, at moderate to good yields. Otherwise, under the same reaction conditions, when X = NEt2 or SPr, the oxidation product 4-formyl-pyrazole was obtained.

中文翻译：

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Selectfluor 促进吡唑的 C-4 位发生意外的无金属氟化和氧化

由 Selectfluor 促进的具有亚甲基 (CH2X) 的吡唑的无金属亲电氟化，其中 X = OH、OMe、F、N3 和 C-4 位的 NHMe，提供了来自意想不到的 C 的 4-氟-吡唑产物-C 键裂解，收益率中等至良好。否则，在相同反应条件下，当X=NEt2或SPr时，得到氧化产物4-甲酰基-吡唑。