Sodium Hydroxide → 1-phenyl-1H-pyrazol-3-amine

Beteiligte Stoffe

Reaktionsschritte

To a solution of 1-phenyl-4,5-dihydro-1H-pyrazol-3-ylamine (50.0 g) in N,N-dimethylformamide (150 ml) and 1,4-dioxane (500 ml) was added 3,4,5,6-tetrachloro-1,4-benzoquinone (84.0 g) under ice-cooling over 20 minutes, and the mixture was stirred at room temperature for 4.5 hours. To the reaction mixture was added a 2M aqueous solution of sodium hydroxide (400 ml) under ice-cooling over 25 minutes, and the mixture was stirred at room temperature for 1 hour. The mixture was filtered through Celite to remove the insoluble substance, and eluted with ethyl acetate (250 ml×3), and then the filtrate was extracted with ethyl acetate (300 ml). The resulting organic layer was sequentially washed with water (300 ml) and a saturated aqueous solution of sodium chloride (300 ml). The separated aqueous layer was extracted twice with ethyl acetate (300 ml). To the combined organic layer were added anhydrous sodium sulfate (50 g) and silica gel (50 g), and the mixture was stirred at room temperature for 1 hour. This mixture was filtered with silica gel (100 g) on Celite, and subjected to elution with ethyl acetate (250 ml×3). The filtrate was concentrated, and diisopropyl ether (500 ml) was added to the resulting residue, and the mixture was stirred at room temperature. The insoluble substance was collected by filtration, washed twice with diisopropyl ether (100 ml), and dried under reduced pressure to give the titled compound (12.2 g).

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