Water → 2,3-dihydro-6-(4-fluorophenyl)-2-oxo-7-(pyridin-4-yl)-1H-imidazo[1,2-b]pyrazole

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Reaction Steps

To a suspension of sodium hydride (288 mg) in N,N-dimethylformamide (20 ml) was added dropwise a solution of 5-amino-3-(4-fluorophenyl)-4-(pyridin-4-yl)pyrazole (1,524 g) in N,N-dimethylformamide (5 ml) with ice cooling. The mixture was stirred for 30 minutes and to the mixture was added a solution of ethyl chloroacetate (883 mg) in N,N-dimethylformamide (5 ml). After stirring of the mixture for 1 hour at ambient temperature, the reaction mixture was poured into water and the separated oil was extracted with dichloromethane. The extract was washed with brine, dried and concentrated in vacuo. The residue was dissolved in a solution of sodium (138 mg) in ethanol (5 ml) and the solution was refluxed for 1 hour. The reaction mixture was cooled, poured into water and neutralized with diluted hydrochloric acid. The separated oil was extracted with dichloromethane and the extract was washed with brine, dried and concentrated in vacuo. The residue was crystallized from ethanol to yield 2,3-dihydro-6-(4-fluorophenyl)-2-oxo-7-(pyridin-4-yl)-1H-imidazo[1,2-b]pyrazole (178 mg).

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