Ethyl Acetate → 2-(2,4-Dichlorophenyl)imidazo[1,2-a]pyridine

HRID 1600550Notes

Reaction equation

HRID 1600550 reaction equation
[NH2:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][N:3]=1.Cl[CH2:9][C:10]([C:12]1[CH:17]=[CH:16][C:15]([Cl:18])=[CH:14][C:13]=1[Cl:19])=O.C(OCC)(=O)C.C(=O)(O)[O-].[Na+]>C(O)C>[Cl:19][C:13]1[CH:14]=[C:15]([Cl:18])[CH:16]=[CH:17][C:12]=1[C:10]1[N:1]=[C:2]2[CH:7]=[CH:6][CH:5]=[CH:4][N:3]2[CH:9]=1

Participants

6

Reactant 4

HCID 8857Ethyl AcetateHCID 104392-AminopyridineHCID 202502,2',4'-Trichloroacetophenone2×HCID 516892Sodium Bicarbonate

Product 1

HCID 41097072-(2,4-Dichlorophenyl)imidazo[1,2-a]pyridineYield 38.3%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

A mixture of 8.4 g (89.2 mmol) 2-aminopyridine and 20.1 g (89.9 mmol) of 2,2',4'-trichloroacetophenone in 300 ml of ethanol was heated at reflux with stirring for 14 h. At this point, another 5.0 g (22.4 mmol) of 2,2',4'-trichloroacetophenone was added and the reaction mixture heated an additional 6 h. Ethyl acetate (400 ml) and excess saturated aqueous sodium bicarbonate were slowly added. After thorough mixing, the ethyl acetate layer was separated and washed with two fold excess water, saturated brine, and dried over magnesium sulfate. Evaporating the solvent in vacuo to almost dryness gave a wet solid residue to which n-butyl chloride was added. This solid was filtered and washed thoroughly with n-butyl chloride before drying. A yield of 9.0 g of the title compound was obtained (m.p. 173-175° C.) as a technical material which was not purified further but used directly in the next step.

Workup

  1. temperaturewas heated
  2. temperatureat reflux
  3. temperaturethe reaction mixture heated an additional 6 h
  4. customAfter thorough mixing, the ethyl acetate layer was separated
  5. washwashed with two fold excess water, saturated brine
  6. dry with materialdried over magnesium sulfate
  7. customEvaporating the solvent in vacuo to almost dryness
  8. customgave a wet solid residue to which n-butyl chloride
  9. additionwas added
  10. filtrationThis solid was filtered
  11. washwashed thoroughly with n-butyl chloride
  12. custombefore drying

Sources & evidence

ORD record
ord-3ac0404a8068447982d27ffe7f6b398f
Source dataset
uspto-grants-1999_11
Patent number
US05977028

Reaction notes

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