Sodium Hydroxide → 3-tert-butyl-4-chloro-1-methyl-1H-pyrazole-5-carboxylic acid

Beteiligte Stoffe

Reaktionsschritte

A mixture of 5-tert-butyl-4-chloro-2-methyl-2H-pyrazole-3-carboxylic acid ethyl ester (prepared as described in the previous step, 2.20 g, 9.00 mmol) and 3 N aqueous NaOH (7.50 mL, 22.5 mmol) in MeOH (40 mL) was stirred at room temperature for 4 h. The solvent was removed under reduced pressure, and the residue was treated with H2O (30 mL) and washed with Et2O. The aqueous layer was then acidified to pH 7 by 2 N aqueous HCl and extracted with DCM. The combined organic layers were washed with brine and dried with Na2SO4. The solvent was removed in vacuo to yield the title compound as a white solid. 1H-NMR (400 MHz, CDCl3) δ: 10.41 (br s, 1H), 4.12 (s, 3H), 1.42 (s, 9H). Mass Spectrum (LCMS, ESI pos.) Calculated for C9H13ClN2O2: 217.1 (M+H), Measured: 217.1.

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