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

HRID 751268Notes

Reaction equation

HRID 751268 reaction equation
S(=O)(=O)(O)O.[K].[CH2:7]([O:9][C:10](=[O:15])[CH:11](Cl)[CH:12]=O)[CH3:8].[NH2:16][C:17]1[CH:22]=[CH:21][C:20]([Br:23])=[CH:19][N:18]=1>C(O)C.C(=O)(O)[O-].[Na+]>[CH2:7]([O:9][C:10]([C:11]1[N:18]2[CH:19]=[C:20]([Br:23])[CH:21]=[CH:22][C:17]2=[N:16][CH:12]=1)=[O:15])[CH3:8]

Participants

6

Reactant 3

HCID 1118Sulfuric AcidHCID 706222-Amino-5-bromopyridineHCID 86623935Ethyl 2-chloro-3-oxopropanoate potassium salt

Product 1

HCID 22031055Ethyl 6-bromoimidazo[1,2-a]pyridine-3-carboxylateYield 55%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 516892Sodium BicarbonateSolvent

Procedure

Add concentrated sulfuric acid (0.56 g, 5.78 mmol) to a suspension of 2-chloro-3-oxo-propionic acid ethyl ester potassium salt (Tetrahedron 2000, 58(40), 7915-7921; 3.27 g, 17.3 mmol) and 2-amino-5-bromopyridine (1.0 g, 5.78 mmol) in ethanol (100 mL). Reflux for 2 h, cool, and carefully dilute with saturated aqueous sodium bicarbonate. Extract in ethyl acetate, combine organic extracts, and concentrate. Flash chromatography using appropriate ethyl acetate/methanol mixtures gives 0.85 g (55%) of the subtitled compound as a white solid. MS ES+m/e 269.0, 271.0 (M+1) bromine isotope. 1H NMR (400 MHz, DMSO-d6) δ 9.32 (m, 1H), 8.28 (s, 1H), 7.79 (d, J=10 Hz, 1H), 7.70 (dd, J=10, 2 Hz, 1H), 4.36 (q, J=7.0 Hz, 2H), 1.33 (t, J=7.0 Hz, 3H).

Workup

  1. temperatureReflux for 2 h
  2. temperaturecool
  3. extractionExtract in ethyl acetate
  4. concentrationconcentrate

Sources & evidence

ORD record
ord-d913589e16424bce909527720c2a4838
Source dataset
uspto-grants-2008_07
Patent number
US07405299B2

Reaction notes

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