Yield:-

Reaction Conditions:

Stage #1: ethyl 1-(4-methoxyphenyl)-3-methyl-1H-pyrazole-5-carboxylatewith sodium hydroxide;ethanol;water at 45;
Stage #2: with hydrogenchloride;water in ethanol at 20;Product distribution / selectivity;

Steps:

10

To a solution of 2-(4-methoxyphenyl)-5-methyl-2H-pyrazole-3-carboxylic acid ethyl ester (1.00 g, 3.84 mmol) in ethanol (20 mL) and water (20 mL) was added a sodium hydroxide solution (50% in water, 1 mL). The solution was stirred at 45° C. overnight. After the solution was allowed to cool to room temperature, 1 N HCl was added until the solution was acidic to pH paper. The solution was extracted with ethyl acetate (3*). The combined organic layers were dried (MgSO₄) and concentrated to give 761 mg of the title compound, which was used in the next reaction without further purification. LC-MS (C₁₂H₁₂N₂O₃ calculated 232) m/z 233 (M+H).

References:

US2007/197526,2007,A1 Location in patent:Page/Page column 14; 15