Sulfuric Acid → Ethyl 6-bromoimidazo[1,2-a]pyridine-3-carboxylate

HRID 570301Notes

Reaction equation

HRID 570301 reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][C:5]([NH2:8])=[N:6][CH:7]=1.[K].Cl[C:11](=[CH:17]O)[C:12]([O:14][CH2:15][CH3:16])=[O:13].S(=O)(=O)(O)O>CCO>[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[N:6]([C:11]([C:12]([O:14][CH2:15][CH3:16])=[O:13])=[CH:17][N:8]=2)[CH:7]=1

Participants

5

Reactant 3

HCID 1118Sulfuric AcidHCID 706222-Amino-5-bromopyridineHCID 86677443Ethyl 2-chloro-3-hydroxyacrylate potassium salt

Product 1

HCID 22031055Ethyl 6-bromoimidazo[1,2-a]pyridine-3-carboxylate

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Conditions

Temperature
78 °C

Procedure

To a stirring suspension of 5-bromopyridin-2-amine (1.2 g, 7.05 mmol) and ethyl 2-chloro-3-hydroxyacrylate potassium salt (6.6 g, 28.19 mmol) (prepared in a similar manner as 22) in EtOH (100 mL) at room temperature was added sulfuric acid (751 μL, 14.10 mmol) dropwise. The reaction mixture was heated at 78° C. overnight. The reaction was cooled to room temperature and the solvent was concentrated. The residue was taken in water and the pH was adjusted between 6-8 with saturated sodium bicarbonate. The crude product was extracted with ethyl acetate. The organic was washed with brine and dried over anhydrous sodium sulfate. The crude product was purified by silica chromatography to yield ethyl 6-bromoimidazo[1,2-a]pyridine-3-carboxylate (24s). MS m/z 270.2 (M+1)+.

Workup

  1. temperatureThe reaction was cooled to room temperature
  2. concentrationthe solvent was concentrated
  3. extractionThe crude product was extracted with ethyl acetate
  4. washThe organic was washed with brine
  5. dry with materialdried over anhydrous sodium sulfate
  6. customThe crude product was purified by silica chromatography

Sources & evidence

ORD record
ord-2ed03d57ff7143dcbd8fa771ce168c49
Source dataset
uspto-grants-2015_05
Patent number
US09023839B2

Reaction notes

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