N-bromobutanimide → 5-Bromo-2-oxindole

HRID 1937545Notes

Reaction equation

HRID 1937545 reaction equation
[NH:1]1[C:9]2[C:4](=[CH:5][CH:6]=[CH:7][CH:8]=2)[CH2:3][C:2]1=[O:10].[Br:11]N1C(=O)CCC1=O>C(#N)C.C(O)C>[Br:11][C:6]1[CH:5]=[C:4]2[C:9](=[CH:8][CH:7]=1)[NH:1][C:2](=[O:10])[CH2:3]2

Participants

5

Reactant 2

HCID 67184N-bromobutanimide2×HCID 321710Oxindole2×

Product 1

HCID 6111935-Bromo-2-oxindoleYield 68%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 6342AcetonitrileSolvent

Conditions

Temperature
7 °C

Procedure

2-Oxindole (53.3 g) was suspended in 640 mL acetonitrile and the mixture cooled to 7° C. in an ice bath with mechanical stirring. Solid N-bromosuccinimide (74.8 g) was added in portions over 20 minutes. After about one-third of the N-bromosuccinimide had been added (over 5 minutes), the temperature had increased to 12° C. The addition was halted until the temperature of the mixture had dropped to 10° C. The addition was resumed keeping the temperature below 12° C. After the addition was complete, the mixture was stirred for 1 hour at 10° C. and then for 1 additional hour during which the mixture was allowed to warm to ambient temperature. The precipitate was collected by vacuum filtration, washed with 80 mL of ethanol and sucked dry for 20 minutes in the filtration funnel to give product containing 6.4% of 2-oxindole by HPLC. The solid was suspended in 1440 mL of denatured ethanol and slurry-washed by stirring and refluxing for 5 minutes at which time most of the solid had dissolved. The mixture was cooled in an ice bath to 13° C. The solid product was collected by vacuum filtration, washed with 80 mL of ethanol and dried under vacuum to give 57.7 g (68.0%) of 5-bromo-2-oxindole containing 1.13% 2-oxindole by HPLC. Slurry-washing with 30% less ethanol gave a better yield (88%) but contained more 2-oxindole (1.76%).

Workup

  1. temperaturethe temperature had increased to 12° C
  2. additionThe addition
  3. additionhad dropped to 10° C
  4. additionThe addition
  5. customthe temperature below 12° C
  6. additionAfter the addition
  7. temperatureto warm to ambient temperature
  8. filtrationThe precipitate was collected by vacuum filtration
  9. washwashed with 80 mL of ethanol
  10. customsucked dry for 20 minutes in the filtration funnel
  11. customto give product
  12. washslurry-washed
  13. stirringby stirring
  14. temperaturerefluxing for 5 minutes at which time most of the solid
  15. dissolutionhad dissolved
  16. temperatureThe mixture was cooled in an ice bath to 13° C
  17. filtrationThe solid product was collected by vacuum filtration
  18. washwashed with 80 mL of ethanol
  19. customdried under vacuum

Sources & evidence

ORD record
ord-95af19a7a186452e92af8d60b04923d6
Source dataset
uspto-grants-2002_05
Patent number
US06395734B1

Reaction notes

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