Chlorosulfonic acid → 1-acetyl-5-bromo-2,3-dihydro-1H-indole-6-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

To 5-bromo-N-acetylindoline 122.86 g (0.51 mol) cooled in an ice bath was added chlorosulfonic acid, 116.52 g (2.6 moles) very cautiously. The mixture was stirred for about 30 minutes at 0° C. and then allowed to warm to room temperature. The mixture was then heated slowly to about 70°-90° C. overnight. After cooling, the cold solution was slowly added to ice and the solids collected by suction filtration, washed several times with water and allowed to dry overnight. The product was recrystallized from chloroform to give 72.5 g (42% by weight yield) of 5-bromo-6-chlorosulfonyl-N-acetylindoline.

Provenance & Evidence