5-Fluoro-7-nitroindole-2,3-dione synthesis

Yield:954571-39-2 94.3%

Reaction Conditions:

with sulfuric acid;nitric acid at -5 - 0;

Steps:

5.3

Step 3: 5-Fluoro-7-nitro-1 H-indole-2, 3-dione; To a solution of 5-fluoro-1 H-indole-2, 3-dione (2.5 g, 15.0 mmol) in cone. H₂SO₄ (9 ml.) was added very slowly fuming nitric acid (1.5 ml.) at -5 to 0⁰C. The reaction mixture was stirred at the same temperature for one hour. After completion of the reaction, the reaction mixture was poured onto crushed ice and the resulting precipitate was filtered, washed with water (2-3 times) and dried under vacuum to obtain the title compound as yellow solid (3 g, 94.30%) which was used for the next step directly.

References:

WO2010/115736,2010,A2 Location in patent:Page/Page column 70