4-Toluenesulfonyl chloride → 1-(toluene-4-sulfonyl)-1H-pyrazole-4-carboxylic acid ethyl ester

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Reaction Steps

To a solution of ethyl 1H-pyrazole-4-carboxylate (4.50 g, 32.11 mmol) in THF was added 60% NaH (1.60 g, 40.00 mmol) in mineral oil. After 20 minutes, p-toluenesulfonyl chloride was added. After 3 hours, the mixture was diluted with saturated aqueous NH4Cl and extracted with ethyl acetate. The combined organic layers were washed with brine, dried over sodium sulfate and concentrated in vacuo. The residue was purified by silica gel chromatography eluting with 30-50% ethyl acetate in heptane. The major fractions were combined and the solvent was concentrated in vacuo to afford 1-(toluene-4-sulfonyl)-1H-pyrazole-4-carboxylic acid ethyl ester.

Provenance & Evidence