Nitric Acid → 5-Nitro-2H-indol-2-one

Participants

Reaction Steps

1,3-Dihydro-indol-2-one 30a (20.0 g, 150 mmol) was dissolved in sulfuric acid (100 ml, 98%) in an ice-water bath under stirring, and added dropwise with nitric acid (10 ml, 65%-68%) while maintaining the temperature below 0° C. Upon completion of the addition, the mixture was stirred for 1 hour at 0° C. After thin lay chromatography showed the disappearance of starting materials, the reaction mixture was added with ice and filtered after ice-out. The filter cake was washed with water (20 ml×3), and the resulting solid was recrystallized to obtain the title compound 5-nitro-indol-2-one 30b (25.3 g, yield 92.4%) as an orange solid.

Provenance & Evidence