Lithium Hydroxide → 1-[2-(Dimethylamino)-2-oxoethyl]-3-(1,1-dimethylethyl)-1H-pyrazole-5-carboxylic acid

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Reaction Steps

To a solution of ethyl 3-tert-butyl-1-(2-(dimethylamino)-2-oxoethyl)-1H-pyrazole-5-carboxylate from example B17 (0.48 g, 1.7 mmol) in THF (10 mL) was added a solution of lithium hydroxide (0.21 g, 5.1 mmol) in water (5 mL) and the mixture was stirred for 16 h at RT. Solvents were removed and the residue was acidified with 3M HCl and the product was extracted with EtOAc (2×30 ml). The combined organic extracts were washed with brine, dried (Na2SO4) and concentrated to afford 3-tert-butyl-1-(2-(dimethylamino)-2-oxoethyl)-1H-pyrazole-5-carboxylic acid (0.4, 93% yield) as a pasty mass. 1H NMR (400 MHz, DMSO-d6): δ 6.69 (s, 1H), 5.30 (s, 2H), 3.02 (s, 3H), 2.82 (s, 3H), 1.24 (m, 9H); MS (ESI) m/z: 254.0 (M+H+).

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