Acetic Anhydride → 1-(5-bromo-6-fluoro-1H-indazol-1-yl)ethanone

Participants

Reaction Steps

To a solution of 77.0 g of N-(4-bromo-5-fluoro-2-methylphenyl)acetamide in 930 mL of toluene were added 93.0 mL of acetic anhydride and 37.0 g of potassium acetate at room temperature, and the resultant solution was heated at 90° C., slowly added dropwise with 67.0 mL of isoamyl nitrite, and stirred at this temperature for 3 hours. After diluting with ethyl acetate, washing successively with water and saturated brine, and drying over anhydrous magnesium sulfate, the solvent was evaporated. The precipitated crystals were washed with diethyl ether:n-hexane=1:10, the filtrate concentrated and purified and separated by silica gel column chromatography (ethyl acetate:n-hexane=0:100-1:5) and finally combined with the previous crystals, to afford 22.5 g of the title compound as pale brown crystals.

Provenance & Evidence