Sulfuric Acid → 5-bromo-6-methoxy-1H-indole-2,3-dione

Participants

Reaction Conditions

Reaction Steps

Concentrated H2SO4 (400 mL) was heated to 50° C. and portions of (2E)-N-[4-bromo-3-(methyloxy)phenyl]-2-(hydroxyimino)ethanamide (75 g, 275 mmol) were added while keeping the internal temperature below 70° C. After complete addition, the mixture was heated to 80° C. for 1 h, then poured into ice, filtered and washed with H2O to yield 5-bromo-6-(methyloxy)-1H-indole-2,3-dione (75 g) of a red solid. MS (m/z) 257.9 (M+H+).

Provenance & Evidence