Hydrochloric Acid → 5-Bromo-7-nitroindoline

Reaction equation

C([N:4]1[C:12]2[C:7](=[CH:8][C:9]([Br:16])=[CH:10][C:11]=2[N+:13]([O-:15])=[O:14])[CH2:6][CH2:5]1)(=O)C.Cl.C(=O)([O-])[O-].[Na+].[Na+]>C(O)C>[Br:16][C:9]1[CH:8]=[C:7]2[C:12](=[C:11]([N+:13]([O-:15])=[O:14])[CH:10]=1)[NH:4][CH2:5][CH2:6]2

Participants

Procedure

1-Acetyl-5-bromo-7-nitroindoline (5.05 g, 17.7 mmol) was added to a mixture comprising 6 ml of ethanol and 40 ml of 6N hydrochloric acid. The obtained mixture was heated under reflux for 3 hours, neutralized with sodium carbonate and extracted with ethyl acetate. The organic phase was washed with water, dried over magnesium sulfate and concentrated. The residue was purified by silica gel column chromatography to give 4.13 g of 5-bromo-7-nitroindoline. This compound (301 mg, 1.24 mmol) was added to 10 ml of toluene, followed by the addition of 580 mg (2.55 mmol) of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The obtained mixture was refluxed by heating under stirring for 3.5 hours and filtered to remove insolubles. The filtrate was concentrated and the obtained residue was purified by silica gel column chromatography to give 252 mg of the title compound.