Lithium hydroxide, monohydrate → 1-tert-Butyl-5-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid

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Reaction Conditions

Reaction Steps

In a solution of ethanol:water:dioxane (1:1:1, 9 mL) was placed ethyl 1-tert-butyl-5-(trifluoromethyl)-1H-pyrazole-4-carboxylate (750 mg, 2.84 mmol) and lithium hydroxide hydrate (357 mg, 8.51 mmol). The mixture was stirred at 40° C. for 3 hrs and then at RT overnight. The mixture was diluted with water (25 mL) and 1N HCl (10 mL) and extracted with ethyl acetate (2×25 mL). The combined organic phases were washed with brine (20 mL), dried (Na2SO4) and evaporated at reduced pressure to afford 1-tert-butyl-5-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid (646 mg, 94% yield) as a solid. 1H NMR (300 MHz, DMSO-d6) δ 1.63 (s, 9H), 7.92 (s, 1H); MS (ESI) m/z: 259.0 (M+Na+).

Provenance & Evidence