Acetic Anhydride → 7-Methoxyindazole

To a solution of N-(2-methoxy-6-methylphenyl)acetamide (9.28 g, 51.8 mmol) in ethyl acetate (100 ml) are added acetic anhydride (14.7 mL, 156 mmol), tetrabutylammonium bromide (0.84 g, 2.61 mmol), potassium acetate (10.16 g, 104 mmol), and isoamyl nitrite (9.1 mL, 67.7 mmol), and the mixture is refluxed for 9 hours. After the reaction is completed, the solvent is evaporated under reduced pressure, and to the obtained residue is added 6N aqueous sodium hydroxide solution (100 mL). The mixture is stirred at room temperature for 1 hour. After the reaction is completed, the pH value of the mixture is adjusted to pH 7–8 with 3N hydrochloric acid, and the mixture is extracted with chloroform. The organic layer is dried over anhydrous magnesium sulfate, and the solvent is evaporated under reduced pressure. The obtained residue is purified by silica gel column chromatography (n-hexane/ethyl acetate=3/1→1/1) to give the title compound (3.95 g, yield: 51%).

1. temperaturethe mixture is refluxed for 9 hours
2. customthe solvent is evaporated under reduced pressure
3. additionto the obtained residue is added 6N aqueous sodium hydroxide solution (100 mL)
4. extractionthe mixture is extracted with chloroform
5. dry with materialThe organic layer is dried over anhydrous magnesium sulfate
6. customthe solvent is evaporated under reduced pressure
7. customThe obtained residue is purified by silica gel column chromatography (n-hexane/ethyl acetate=3/1→1/1)

ORD record

ord-c232f6724b1b431c9e0a76cdad7ed912

Source dataset

uspto-grants-2007_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07217724B2