Potassium Hydroxide → 1-(1-((tert-butoxy)carbonyl)piperidin-4-yl)-1H-pyrazole-4-carboxylic acid

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A mixture of ethyl 1H-pyrazole-4-carboxylate (700 mg, 5 mmol) and NaH 60% (6 mmol) was stirred under nitrogen at 0° C. for 1 hour in dry DMF (15 mL). tert-Butyl 4-[(methylsulfonyl)oxy]piperidine-1-carboxylate (1.53 gr, 5.5 mmol) dissolved in 4 mL of dry DMF was added and the resulting solution was heated at 100° C. overnight. Reaction mixture was quenched with water and extracted (×3) with ethyl acetate. Collected organic phases were dried over Na2SO4, filtered and evaporated to dryness. Residue was dissolved in MeOH (20 mL) and water (5 mL) and KOH (1.12 gr, 20 mmol) was added. The resulting solution was stirred at room temperature 24 hours, then solvents removed under reduced pressure. The residue was taken-up with AcOEt and KHSO4 5% solution. Acqueous phase was extracted with EtOAc several times. Collected organic phases were dried with Na2SO4, filtered and evaporated to dryness affording 600 mg of the title compound.

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