Iodine → 4-bromo-2,3-dihydro-1H-indol-2-one

Participants

Reaction Steps

Add a solution of I2 (2.62 g, 10.30 mmol) in DMF (10 mL) dropwise to a solution of 4-bromoindole (2.00 g, 10.20 mmol) and KOH (1.43 g, 25.5 mmol) in DMF (40 mL). Stir for 30 min at room temperature and add saturated aqueous Na2SO3. Stir at room temperature for 15 min, then dilute reaction mixture with ethyl acetate (100 mL). Wash organics three times with H2O, dry organics (MgSO4) and concentrate to a brown oil. Dissolve oil in 2-methoxyethanol (40 mL) and heat to 100° C. Add H3PO4 (9 mL) and heat to reflux for 48 h. Cool to room temperature and dilute with H2O (75 mL). Extract into ethyl acetate, dry MgSO4) and concentrate organics to a dark brown oil. Chromatograph on silica gel (90 g), eluting with 20% to 40% ethyl acetate/hexanes to afford 121 mg (6%) of the title compound as a tan solid. MS (ES) 212,214 (M+H), 210,212 (M−H); HPLC shows 76% purity.

Provenance & Evidence