Tetrahydrofuran → 6-(3-{[3-(1-Cyano-1-methylethyl)benzoyl]amino}phenoxy)imidazo[1,2-b]pyridazine-2-carboxylic acid

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Reaction Steps

To a mixture of 3-(1-cyano-1-methylethyl)benzoic acid (454 mg, 2.40 mmol), tetrahydrofuran (10 mL) and N,N-dimethylformamide (0.01 mL) was added oxalyl chloride (366 mg, 2.88 mmol), and the mixture was stirred at room temperature for 2 hr. The solvent was evaporated under reduced pressure, tetrahydrofuran was added to the residue, and the mixture was azeotroped twice. The residue was dissolved in N-methylpyrrolidone (4 mL), added to a solution of ethyl 6-(3-aminophenoxy)imidazo[1,2-b]pyridazine-2-carboxylate (350 mg, 1.17 mmol) in N-methylpyrrolidone (6 mL), and the mixture was stirred at room temperature for 2 hr. Ethyl acetate was added to the reaction mixture, and the mixture was washed with saturated aqueous sodium hydrogencarbonate solution, dried over anhydrous magnesium sulfate, and filtrated. To the residue were added 8N aqueous sodium hydroxide solution (4.0 mL) and methanol (10.0 mL), and the mixture was stirred at room temperature for 10 min. 6N Hydrochloric acid (5.0 mL) and water (60 mL) were added to the mixture, and the mixture was extracted with ethyl acetate (150 mL). The extract was dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was washed with hexane to give the title compound (828 mg, 94%) as a white powder.

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