Trifluoroacetic acid → 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one

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Reaction Steps

To 1.10 g (2.30 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 4-(b) were added 30 ml of dichloromethane and 6 ml of trifluoroacetic acid, and the mixture was stirred under room temperature for 2.5 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, 20 ml of methanol and 2 ml of 28% aqueous ammonia were added to the obtained solid, and the mixture was stirred under room temperature for 12 hours. Then, water was added to the solution, precipitated solid was collected by filtration, washed with water, and then, dried under reduced pressure. To the obtained dried material was added ethyl acetate to dissolve therein, diisopropyl ether was added to the solution and precipitated solid was collected by filtration. The obtained solid was dried under reduced pressure to obtain 0.54 g of the title compound as a white solid. (Yield: 67%)

Provenance & Evidence