反应详情

温度

75 °C

Methyl 3-amino-6-fluoro-2-methylbenzoate (7.50 g, 0.041 mol) was dissolved in 150 mL of acetic acid. To this was added acetic anhydride (14.6 g, 0.143 mol) and the mixture was warmed to 75° C. Sodium nitrite (11.3 g, 0.164 mol) was added in portions to the reaction mixture (evolution of an gas observed). The mixture was stirred at 75° C. for 16 hours, then allowed to cool to ambient temperature, and then poured into cold 10% aqueous potassium carbonate solution. This material was extracted twice with EtOAc, the extracts dried over sodium sulfate and concentrated under reduced pressure. Column chromatography (1:1 EtOAc/Hexanes) afforded 0.48 g of methyl 1-acetyl-5-fluoro-1H-indazole-4-carboxylate. The crude material was then added to 5 mL of 4M HCl/dioxane and 15 mL of methanol in a pressure tube and heated to 60° C. for 2 hours. The mixture was concentrated under reduced pressure and the resulting solids were taken up in 10% aqueous potassium carbonate/EtOAc. The organic layer was isolated, dried over sodium sulfate and concentrated under reduced pressure to give 0.483 g (5%) of the title compound.

1. temperatureto cool to ambient temperature
2. extractionThis material was extracted twice with EtOAc
3. dry with materialthe extracts dried over sodium sulfate
4. concentrationconcentrated under reduced pressure