Lithium Hydroxide → 3-tert-butyl-1-(2-(dimethylamino)ethyl)-1H-pyrazole-5-carboxylic acid

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Reaction Steps

To a solution of ethyl 3-tert-butyl-1-(2-(dimethylamino)ethyl)-1H-pyrazole-5-carboxylate (0.47 g, 1.8 mmol) in THF (10 mL) was added aqueous LiOH (0.22 g, 5.3 mmol, 5 mL) and the mixture was stirred for 16 h at RT. Solvents were removed, the thick liquid was diluted with water (5 mL) and acidified with 50% aq. acetic acid solution to pH 5-6. The product was extracted with EtOAc (2×50 ml) and the combined organics were washed with brine, dried (Na2SO4) and concentrated in vacuo to afford 3tert-butyl-1-(2-(dimethylamino)ethyl)-1H-pyrazole-5-carboxylic acid as a pasty mass (0.12 g, 29% yield). 1H NMR (400 MHz, DMSO-d6): δ 6.56 (s, 1H), 4.66 (t, J=6.0 Hz, 2H), 3.17 (t, J=6.0 Hz, 2H), 2.53 (s, 6H), 1.17 (s, 9H); MS (ESI) m/z: 240.3 (M+H+).

Provenance & Evidence