Nitric Acid → 5-Fluoro-7-nitro-1,3-dihydro-indol-2-one

Participants

Reaction Conditions

Reaction Steps

5-Fluoro-1,3-dihydro-indol-2-one 4a (5.0 g, 33 mmol) was dissolved in sulfuric acid (17.6 ml, 98%) under stirring at −5° C., and nitric acid (2.1 ml, 65%-68%) was added to the solution while maintaining the temperature below 0° C. Upon completion of the addition, the mixture was stirred at room temperature for 1 hour. After thin lay chromatography showed the disappearance of starting materials, the reaction mixture was poured into ice water and filtered after ice-out. The filter cake was washed with water for three times, and the resulting solid was recrystallized to obtain the title compound 5-fluoro-7-nitro-1,3-dihydro-indol-2-one 20a (4.0 g, yield 62.5%) as an orange solid.

Provenance & Evidence