Water → 2-methyl-1H-indol-5-ol

HRID 2180131Notes

Reaction equation

B(Br)(Br)Br.C[O:6][C:7]1[CH:8]=[C:9]2[C:13](=[CH:14][CH:15]=1)[NH:12][C:11]([CH3:16])=[CH:10]2.O.[OH-].[Na+]>C(Cl)Cl>[OH:6][C:7]1[CH:8]=[C:9]2[C:13](=[CH:14][CH:15]=1)[NH:12][C:11]([CH3:16])=[CH:10]2

Participants

Conditions

Temperature: -45 °C

Procedure

A solution of boron tribromide (32.5 ml, 341 mmol) in methylene chloride (60 ml) was added in portions to a solution of 5-methoxy-2-methylindole (25 g, 155 mmol) in methylene chloride (250 ml) cooled at −45° C. After stirring for 15 minutes at −30° C., the mixture was warmed up to ambient temperature and stirred for 1 hour. Methylene chloride (300 ml) was added in portions and the mixture was cooled to 0° C. Water was added in portions and the mixture was adjusted to pH6 with 4N sodium hydroxide. The organic layer was separated. The aqueous layer was extracted with methylene chloride and the organic layers were combined, washed with water, brine, dried (MgSO4) and the volatiles were removed by evaporation. The residue was purified by column chromatography eluting with ethyl acetate/methylene chloride (1/9 followed by 15/85) to give 5-hydroxy-2-methylindole (21.2 g, 93%).

Workup

temperaturethe mixture was warmed up to ambient temperature
stirringstirred for 1 hour
temperaturethe mixture was cooled to 0° C
customThe organic layer was separated
extractionThe aqueous layer was extracted with methylene chloride
washwashed with water, brine
dry with materialdried (MgSO4)
customthe volatiles were removed by evaporation
customThe residue was purified by column chromatography
washeluting with ethyl acetate/methylene chloride (1/9 followed by 15/85)

Sources & evidence

ORD record: ord-e68e2cc6330d4428b428c659864822d2
Source dataset: uspto-grants-2005_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06887874B2

Reaction notes

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