Lithium borohydride → 5-bromo-7-ethyl-1H-indole

HRID 2249529Notes

Reaction equation

HRID 2249529 reaction equation
[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[C:9]([CH2:11][CH3:12])[CH:10]=1)[NH:7][C:6](=O)[C:5]2=O.[BH4-].[Li+]>O1CCCC1>[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[C:9]([CH2:11][CH3:12])[CH:10]=1)[NH:7][CH:6]=[CH:5]2

Participants

4

Reactant 2

HCID 4148881Lithium borohydrideHCID 80338135-Bromo-7-ethylindoline-2,3-dione

Product 1

HCID 210715755-bromo-7-ethyl-1H-indole

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Conditions

Temperature
90 °C

Procedure

To a solution of 5-bromo-7-ethyl-1H-indole-2,3-dione (36.0 g, 144 mmol) in tetrahydrofuran (120 mL) at room temperature was dropped a 2.0 M solution of lithium borohydride in tetrahydrofuran. The reaction mixture was stirred at 90° C. (oil bath) for 5 hours. After cooling down to room temperature, it was quenched with 5% hydrochloric acid solution until the excess lithium borohydride was destroyed. To the mixture was added saturated sodium bicarbonate solution (300 mL) and extracted with ethyl acetate. Extracts were dried over magnesium sulfate and concentrated under reduced pressure to give the crude product of 5-bromo-7-ethyl-1H-indole, which went to next reaction without further purification.

Workup

  1. temperatureAfter cooling down to room temperature
  2. customit was quenched with 5% hydrochloric acid solution until the excess lithium borohydride
  3. customwas destroyed
  4. additionTo the mixture was added saturated sodium bicarbonate solution (300 mL)
  5. extractionextracted with ethyl acetate
  6. dry with materialExtracts were dried over magnesium sulfate
  7. concentrationconcentrated under reduced pressure

Sources & evidence

ORD record
ord-6addc04c770341d6b629519ca5476b86
Source dataset
uspto-grants-2008_01
Patent number
US07314886B2

Reaction notes

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