Chloroacetaldehyde → 7-Chloroimidazo(1,2-a)pyridine

HRID 985522Notes

Reaction equation

HRID 985522 reaction equation
[Cl:1][C:2]1[CH:7]=[CH:6][N:5]=[C:4]([NH2:8])[CH:3]=1.Cl[CH2:10][CH:11]=O.C(=O)([O-])O.[Na+]>O.C(O)C>[Cl:1][C:2]1[CH:7]=[CH:6][N:5]2[CH:10]=[CH:11][N:8]=[C:4]2[CH:3]=1

Participants

6

Reactant 3

HCID 33ChloroacetaldehydeHCID 516892Sodium BicarbonateHCID 5818662-Amino-4-chloropyridine

Product 1

HCID 196959017-Chloroimidazo(1,2-a)pyridineYield 75%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 962WaterSolvent

Procedure

A stirred suspension of 4-chloropyridin-2-ylamine (6.20 g, 48.2 mmol), chloroacetaldehyde (11.4 g of a 50 wt % solution in water, 73 mmol) and sodium hydrogencarbonate (8.09 g, 96.4 mmol) in ethanol (70 ml) was heated under reflux for 6 h. The solvent was evaporated and the residue partitioned between ethyl acetate and water. The organic layer was washed with brine, dried over sodium sulphate and concentrated in vacuo to give an orange oil. This oil was purified by silica gel chromatography eluting with 50% ethyl acetate in isohexane to afford 7-chloroimidazo[1,2-α]pyridine (5.60 g, 75%) as a white crystalline solid. 1H NMR (400 MHz, CDCl3) δH 6.78 (1H, d, J 7), 7.56 (1H, s), 7.63 (2H, s), 8.05 (1H, d, J 7).

Workup

  1. temperatureunder reflux for 6 h
  2. customThe solvent was evaporated
  3. customthe residue partitioned between ethyl acetate and water
  4. washThe organic layer was washed with brine
  5. dry with materialdried over sodium sulphate
  6. concentrationconcentrated in vacuo
  7. customto give an orange oil
  8. customThis oil was purified by silica gel chromatography
  9. washeluting with 50% ethyl acetate in isohexane

Sources & evidence

ORD record
ord-192a832a28b84d77983e81c47e3a2d32
Source dataset
uspto-grants-2005_03
Patent number
US06872731B2

Reaction notes

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