Phosphorus oxychloride → 5,7-dichloro-4H-imidazo[4,5-b]pyridine

HRID 868501Notes

Reaction equation

HRID 868501 reaction equation
[Cl:1][C:2]1[CH:7]=[CH:6][N+:5]([O-])=[C:4]2[NH:9][CH:10]=[N:11][C:3]=12.P(Cl)(Cl)([Cl:14])=O>>[Cl:14][C:6]1[N:5]=[C:4]2[NH:9][CH:10]=[N:11][C:3]2=[C:2]([Cl:1])[CH:7]=1

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178526259HCID 178526259, compound

Product 1

HCID 1784781755,7-dichloro-4H-imidazo[4,5-b]pyridine

Procedure

7-Chloro-3H-imidazo[4,5-b]pyridine-4-oxide (15 g, 88.5 mMol) and 300 mL phosphorus oxychloride were heated at 110° C. under a nitrogen atmosphere. After 4 hours the excess phosphorus oxychloride was removed in vacuo. The residue was dissolved in water and the solution was neutralized by the addition of aqueous ammonium hydroxide. The suspension was cooled and the solid isolated. After drying, the product, 5,7-dichloro-3H-imidazo[4,5-b]pyridine, weighed 10.5 g (54.5 mMol, 61.6%); m.p. 263° C.; NMR (DMSO-d6): 8.58 δ (s, 1H, H2); 7.58 (s, 1H, H5).

Workup

  1. customAfter 4 hours the excess phosphorus oxychloride was removed in vacuo
  2. dissolutionThe residue was dissolved in water
  3. additionthe solution was neutralized by the addition of aqueous ammonium hydroxide
  4. temperatureThe suspension was cooled
  5. customthe solid isolated
  6. customAfter drying

Sources & evidence

ORD record
ord-3759ad3fffb543f6968f4c211669f3ac
Source dataset
uspto-grants-1988_10
Patent number
US04780452

Reaction notes

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