Sodium borohydride → 4-Chloro-2-methyl-2,3-dihydro-1H-indole

HRID 2058502Notes

Reaction equation

HRID 2058502 reaction equation
[BH4-].[Na+].[CH3:3][C:4]1[NH:5][C:6]2[C:11]([CH:12]=1)=[C:10]([Cl:13])[CH:9]=[CH:8][CH:7]=2.[Cl-].[Al+3].[Cl-].[Cl-]>N1C=CC=CC=1>[CH3:3][CH:4]1[CH2:12][C:11]2[C:6](=[CH:7][CH:8]=[CH:9][C:10]=2[Cl:13])[NH:5]1

Participants

5

Reactant 3

HCID 4311764Sodium borohydrideHCID 6451240Aluminum(III) ChlorideHCID 218145654-Chloro-2-methyl-1H-indole

Product 1

HCID 204796784-Chloro-2-methyl-2,3-dihydro-1H-indoleYield 76.3%

Reagents, catalysts & solvents 1

HCID 1049PyridineSolvent

Procedure

5 g of sodium borohydride was added to 66 ml of pyridine having dissolved therein 4.4 g of 2-methyl-4-chloroindole. To the mixture were added gradually 10.6 g of fine powders of aluminum chloride while ice-cooling with stirring. After completion of addition, the mixture was stirred and allowed to react at room temperature for 27 hours, the solvent was removed therefrom under reduced pressure. Water was added to the residue and the mixture was extracted with 100 ml of benzene. The benzene layer was washed with a saturated aqueous sodium chloride solution followed by concentrating. To the residue was added a 10% aqueous hydrochloric acid which caused foaming. After foaming ceased, the mixture was rendered neutral with an aqueous sodium carbonate solution followed by extracting the mixture with 100 ml of benzene. The benzene layer was dried over anhydrous sodium sulfate. After removing the solvent under reduced pressure, the extract was purified through a silica gel column chromatography (eluant:chloroform) to obtain 3.4 g of 2-methyl-4-chloroindoline which was confirmed by NMR.

Workup

  1. dissolutiondissolved
  2. temperaturecooling
  3. additionAfter completion of addition
  4. stirringthe mixture was stirred
  5. customto react at room temperature for 27 hours
  6. customthe solvent was removed
  7. additionWater was added to the residue
  8. extractionthe mixture was extracted with 100 ml of benzene
  9. washThe benzene layer was washed with a saturated aqueous sodium chloride solution
  10. concentrationby concentrating
  11. additionTo the residue was added a 10% aqueous hydrochloric acid which
  12. extractionby extracting the mixture with 100 ml of benzene
  13. dry with materialThe benzene layer was dried over anhydrous sodium sulfate
  14. customAfter removing the solvent under reduced pressure
  15. customthe extract was purified through a silica gel column chromatography (eluant:chloroform)

Sources & evidence

ORD record
ord-75fe8fe2126e49528a58f50b1e38f7f6
Source dataset
uspto-grants-1982_03
Patent number
US04317820

Reaction notes

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