1-(4-methoxy-benzyl)-4-nitro-1H-pyrazole-3-carboxylic acid ethyl ester → 1-[(4-Methoxyphenyl)methyl]-4-nitro-1H-pyrazole-3-carboxylic acid

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Reaction Steps

A mixture of 1-(4-methoxy-benzyl)-4-nitro-1H-pyrazole-3-carboxylic acid ethyl ester (15.9 g, 52 mmol) in 2 M aqueous NaOH/MeOH (1:1, 400 ml) was stirred at ambient temperature for 14 h. Volatile materials were removed in vacuo, the residue dissolved in EtOAc (200 ml), water (100 ml) added and the mixture taken to pH 3 using 1M aqueous HCl. The layers were separated and the organic portion washed with saturated aqueous sodium hydrogen carbonate. EtOAc was added to the aqueous layer which was acidified to pH 3-4, and the combined organic portions dried (MgSO4) and reduced in vacuo to give 1-(4-methoxy-benzyl)-4-nitro-1H-pyrazole-3-carboxylic acid (13 g, 86%) as a white solid. (LC/MS: Rt 2.63, [M+H]+ 292).

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