Boron tribromide → 6-Bromo-5-hydroxy-1H-indole-2-carboxylic acid ethyl ester
Reaction equation
[CH2:1]([O:3][C:4]([C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][C:11]([O:15]C)=[C:10]([Br:17])[CH:9]=2)=[O:5])[CH3:2].B(Br)(Br)Br.C(=O)(O)[O-].[Na+]>ClCCl>[CH2:1]([O:3][C:4]([C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][C:11]([OH:15])=[C:10]([Br:17])[CH:9]=2)=[O:5])[CH3:2]Participants
Procedure
The solution of 8.30 g (27.8 mmol) 6-bromo-5-methoxy-1H-indole-2-carboxylic acid ethyl ester (prepared according to J. Org. Chem. 1974, 39, 3580) in 160 mL dichloromethane was cooled to −78° C. At this temperature, 55.7 mL boron tribromide (55.7 mmol; 1M solution in dichloromethane) were added. The solution was allowed to warm to room temperature and after 30 min. the solution was poured on 10% aqueous sodium bicarbonate solution, the phases were separated and the aqueous phase was extracted three times with ethyl acetate. The combined organic layers were washed with water followed by brine, dried over magnesium sulfate, filtered and evaporated. The residue was flash-chromatographed on silica gel with n-hexane:ethyl acetate (2:1 v/v) as eluant to give 5.7 g (72%) of the product as a light yellow solid.
Workup
- customthe phases were separated
- extractionthe aqueous phase was extracted three times with ethyl acetate
- washThe combined organic layers were washed with water
- dry with materialdried over magnesium sulfate
- filtrationfiltered
- customevaporated
- customThe residue was flash-chromatographed on silica gel with n-hexane:ethyl acetate (2:1 v/v) as eluant
Sources & evidence
- ORD record
- ord-6cf72996429d4186985615eefc126f91
- Source dataset
- uspto-grants-2009_08
- Patent number
- US07579351B2
Reaction notes
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