Sulfuric Acid → 3-[2-(2-Carboxycyclohexyl)-3-oxo-2,3-dihydropyridazin-6-yl]-2-phenylpyrazolo[1,5-a]pyridine

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Reaction Steps

A mixture of 3-[2-(2-cyanocyclohexyl)-3-oxo-2,3-dihydropyridazin-6-yl]-2-phenylpyrazolo[1,5-a]pyridine (130 mg) and conc. sulfuric acid (1.5 ml) was stirred at room temperature for 45 minutes. Then, the mixture was cooled in an ice-bath and treated with saturated aqueous sodium bicarbonate to make pH of the mixture to 2.0. The mixture was extracted with a mixture of ethyl acetate and tetrahydrofuran. The organic extract was dried over anhydrous sodium sulfate and evaporated in vacuo. The crude product was crystallized from diethyl ether to give colorless crystals of 3-[2-(2-carboxycyclohexyl)-3-oxo-2,3-dihydropyridazin-6-yl]-2-phenylpyrazolo[1,5-a]pyridine (0.10 g).

Provenance & Evidence