Iodine → 7-Bromo-3-methyl-1H-indole

HRID 1198559Notes

Reaction equation

HRID 1198559 reaction equation
[Mg].II.Br[CH:5]=[CH:6][CH3:7].[Br:8][C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=1[N+:15]([O-])=O>C1COCC1>[Br:8][C:9]1[CH:14]=[CH:13][CH:12]=[C:11]2[C:10]=1[NH:15][CH:5]=[C:6]2[CH3:7]

Participants

6

Reactant 4

HCID 807IodineHCID 113411-Bromo-2-nitrobenzeneHCID 115331-Bromo-1-propene2×HCID 5462224Magnesium

Product 1

HCID 130306067-Bromo-3-methyl-1H-indole

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent3×

Conditions

Temperature
-40 °C

Procedure

Magnesium turnings (1.45 g) in dry THF (10 ml) were stirred at room temperature under nitrogen and an iodine crystal added, followed by a few milliliters of a solution of 1-bromo-1-propene (7.25 g, 0.06 mole) in dry THF (50 ml). After warming to initiate the reaction, the remaining bromopropene solution was added dropwise at a rate to maintain reflux. After addition, the reaction was heated at reflux for a further hour, cooled and added rapidly to a stirred solution of 2-bromonitrobenzene (4.04 g, 0.02 mole) in dry THF (70 ml) at -40° C. under nitrogen. The reaction mixture was stirred for a further 30 minutes at -40° C., then was quenched with saturated aqueous ammonium chloride and extracted into diethyl ether. The combined organic extracts were washed with water, dried, filtered and evaporated in vacuo. The crude product was purified by flash chromatography on silica, eluting with 25% diethyl ether in hexane, to yield a yellow-orange oil.

Workup

  1. temperatureAfter warming
  2. customthe reaction
  3. temperatureto maintain
  4. temperaturereflux
  5. additionAfter addition
  6. temperaturethe reaction was heated
  7. temperatureat reflux for a further hour
  8. temperaturecooled
  9. customwas quenched with saturated aqueous ammonium chloride
  10. extractionextracted into diethyl ether
  11. washThe combined organic extracts were washed with water
  12. customdried
  13. filtrationfiltered
  14. customevaporated in vacuo
  15. customThe crude product was purified by flash chromatography on silica
  16. washeluting with 25% diethyl ether in hexane
  17. customto yield a yellow-orange oil

Sources & evidence

ORD record
ord-e115309efa1c41f89d92ab0dd2aebbcc
Source dataset
uspto-grants-1994_01
Patent number
US05281593

Reaction notes

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