Triethylamine → 6-(3-Nitrophenyl)-7-pyridin-4-yl-pyrazolo[5,1-b]thiazole

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Reaction Steps

3-Hydroxy-6-(3-nitrophenyl)-7-pyridin-4-yl-2,3-dihydro-pyrazolo[5,1-b]thiazole (1 g, 2.938 mmol) was dissolved in dimethoxyethane (15 mL) under nitrogen atmosphere. Trifluoroacetic anhydride (0.8 mL, 5.664 mmol, 2 eq) and triethylamine (0.41 mL, 2.938 mmol, 1 eq) were added and the mixture was stirred at room temperature for 3 days. The solution was then diluted with ethyl acetate and washed with saturated aqueous NaHCO3 and brine, dried and evaporated to dryness. The crude product was purified by chromatography on silica gel (eluant: DCM/MeOH 97:3) to give 417 mg (44%) of 6-(3-nitrophenyl)-7-pyridin-4-yl-pyrazolo[5,1-b]thiazole as white solid.

Provenance & Evidence