Acetic Acid → 5-{[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethyl]-amino}-2H-pyrazole-3-carboxylic acid methyl ester

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Reaction Steps

To a solution of 3-(4-fluoro-phenyl)-5-methyl-isoxazole-4-carbaldehyde (1.75 g, 8.53 mmol) and the 5-amino-2H-pyrazole-3-carboxylic acid methyl ester hydrochloride (1.2 g, 8.53 mmol) in methanol (70 mL) at room temperature was added molecular sieves (2.5 g) and then after 1 h, acetic acid (6.8 mL, 119.4 mmol) was added. Then sodium cyanoborohydride (1.07 g, 17.1 mmol) was added portionwise and the mixture stirred at room temperature overnight. After evaporation, dichloromethane was added and the mixture washed with sodium hydrogen carbonate (saturated solution). The organic layer was then dried over sodium sulfate, filtered and evaporated. Purification by chromatography (silica, heptane:ethyl acetate 7:3 to 6:4) afforded 5-{[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethyl]-amino}-2H-pyrazole-3-carboxylic acid methyl ester (1.2 g, 44%).

Provenance & Evidence