187949-90-2

mmol) in a solvent mixture of methanol (200 mL). The reaction mixture was heated to reflux for 17 h, followed by cooling to room temperature and filtration. The filtrate was acidified with 2 N HCl solution to pH=7. The precipitated solid was collected by filtration and dried under reduced pressure to afford the target compound 5-amino-1-(4-fluorophenyl)-1H-pyrazole-4-carboxylic acid as a light yellow solid (18.64 g, 95% yield), which was used in subsequent reactions without further purification.

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[2] Bioorganic and Medicinal Chemistry Letters, 2016, vol. 26, # 20, p. 5032 - 5038
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