DL-cysteine → 2-(1-(tert-butyl)-5-(4-fluorophenyl)-1H-pyrazol-4-yl)-4,5-dihydrothiazole-4-carboxylic acid

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Reaction Conditions

Reaction Steps

A mixed solution of 1N aqueous sodium hydroxide solution (2.65 ml, 2.65 mmol) of the compound (430 mg, 1.77 mmol) obtained in step 1 and DL-cysteine (321 mg, 2.65 mmol), and ethanol (5.3 mL) was stirred at 80° C. for 3 hr. DL-cysteine (200 mg) and 1N aqueous sodium hydroxide solution (1.5 mL) were further added thereto, and the mixture was stirred at 80° C. for 14 hr. DL-cysteine (321 mg) and 1N aqueous sodium hydroxide solution (2.65 mL) were further added thereto, and the mixture was stirred at 80° C. for 5 hr. The reaction mixture was concentrated under reduced pressure, and 1N hydrochloric acid and ethyl acetate were added thereto. The organic layer was washed with saturated brine and dried, and the solvent was evaporated under reduced pressure. The residue was crystallized from ethyl acetate and diethyl ether to give 2-(1-(tert-butyl)-5-(4-fluorophenyl)-1H-pyrazol-4-yl)-4,5-dihydrothiazole-4-carboxylic acid (385 mg, 1.108 mmol, 62.7%) as a pale-yellow powder.

Provenance & Evidence