Chlorosulfonic acid → 2-oxo-2,3-dihydro-1H-indole-5-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

Oxindole (2 g, 15 mmol) was added in portions to chlorosulphonic acid (5 ml, 75 mmol) cooled at 5° C. The mixture was stirred at ambient temperature for 10 minutes and then heated at 80° C. for 30 minutes. The mixture was allowed to cool, and then poured onto ice. The precipitate was collected by filtration, washed with water, and dried over phosphorus pentoxide to give 5-chlorosulphonyloxindole (2.8 g, 80%).

Provenance & Evidence