Sodium Hydroxide → 5-[2-(4-Methoxyphenyl)-ethyl]-1H-pyrazole-3-carboxylic acid

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Reaction Steps

Freshly prepared aq. NaOH (10 M in H2O, 25.4 mmol) was added to a stirring, room temperature solution of 23 (1.391 g, 5.07 mmol) in MeOH (12.7 mL, 0.4 M) under N2. The reaction was then heated to reflux until the reaction was judged complete by HPLC (30 min): The reaction was concentrated and then dissolved in 10 mL H2O. The reaction was extracted with a small amount of EtOAc, then the aqueous layer was made acidic (pH=2) with the dropwise addition of 10% aq. HCl. The white solid that precipitated from the reaction was filtered off and washed with cold H2O. The solid was dried under vacuum overnight to obtain 0.3771 g of relatively pure 24. 24 was further purified by recrystallization from warm MeOH to obtain 0.1317 g of pure 24. No attempts were made to recover remaining 24 from the mother liquor. 1H (CD3OD, 400 MHz): δ 7.07 (2H, d, J=8.2 Hz), 6.84 (2H, d, J=8.6 Hz), 6.53 (1H, s), 3.73 (3H, s), 2.97-2.84 (4H, m) ppm. 13C (CD3OD, 100 MHz): δ 164.86, 159.60, 148.26, 143.15, 134.01, 130.36, 114.81, 107.50, 55.60, 35.67, 29.10 ppm.

Provenance & Evidence