Boron tribromide → 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylic acid

HRID 2375807Notes

Reaction equation

HRID 2375807 reaction equation
C([O:3][C:4]([C:6]1[NH:7][C:8]([CH3:13])=[C:9]([Br:12])[C:10]=1[CH3:11])=[O:5])C.B(Br)(Br)Br>C(Cl)Cl>[Br:12][C:9]1[C:10]([CH3:11])=[C:6]([C:4]([OH:5])=[O:3])[NH:7][C:8]=1[CH3:13]

Participants

4

Reactant 2

HCID 25134Boron tribromide2×HCID 138486ethyl 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylate

Product 1

HCID 215256154-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylic acidYield 150.5%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylic acid ethyl ester (900 mg) was added 10 mL of a solution of boron tribromide (1 M) in DCM. The mixture was stirred at RT for 16 hours (h), then heated under reflux for 5 h. To complete the reaction neat boron tribromide (1.5 mL) was added dropwise and refluxing was continued for 3 h. After cooling to RT the mixture was poured onto crushed ice and extracted with DCM. The combined organic phases were filtered through a plug of diatomaceous earth and concentrated under reduced pressure to give crude 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylic acid (1.2 g) which was used directly in the next step.

Workup

  1. temperatureheated
  2. temperatureunder reflux for 5 h
  3. additionwas added dropwise
  4. temperaturerefluxing
  5. waitwas continued for 3 h
  6. temperatureAfter cooling to RT the mixture
  7. additionwas poured
  8. customonto crushed ice
  9. extractionextracted with DCM
  10. filtrationThe combined organic phases were filtered through a plug of diatomaceous earth
  11. concentrationconcentrated under reduced pressure

Sources & evidence

ORD record
ord-3ec2b649bf7843d599b5e5a12f9331cd
Source dataset
uspto-grants-2008_12
Patent number
US07465806B2

Reaction notes

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