Tetrahydrofuran → 1-Methyl-5-(4-methyl-2-nitro-phenylamino)-1H-pyrazole-4-carboxylic Acid Ethyl Ester

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Reaction Steps

Sodium hydride (60% dispersion in oil, 7.28 g, 180 mmol) was added portionwise to a solution of ethyl 5-amino-1-methylpyrazole-4-carboxylate (21.8 g, 148 mmol) in anhydrous THF at 0° C. The mixture was allowed to warm to room temperature and stirred for 1 h then a solution of 3-fluoro-4-nitrotoluene (20 g, 129 mmol) in anhydrous THF (50 ml) was added dropwise. The resultant deep purple solution was stirred at room temperature for 18 h then poured into ice-cold 1N hydrochloric acid. The resulting mixture was extracted with dichloromethane (200 ml×2), and the combined organic extracts were washed with brine and concentrated in vacuo. The residue was purified by flash chromatography on silica gel (eluant; 60% pet ether:40% EtOAc) to yield the title compound (28.00 g, 61%).

Provenance & Evidence