Chloroacetic Acid → 2,6-Dichloroimidazo[1,2-A]pyridine

HRID 2051122Notes

Reaction equation

HRID 2051122 reaction equation
[Cl:1][CH2:2][C:3](O)=O.C(N(CC)CC)C.[NH2:13][C:14]1[CH:19]=[CH:18][C:17]([Cl:20])=[CH:16][N:15]=1>C(#N)C>[Cl:1][C:2]1[N:13]=[C:14]2[CH:19]=[CH:18][C:17]([Cl:20])=[CH:16][N:15]2[CH:3]=1

Participants

5

Reactant 3

HCID 300Chloroacetic AcidHCID 8471TriethylamineHCID 661742-Amino-5-chloropyridine

Product 1

HCID 117692572,6-Dichloroimidazo[1,2-A]pyridineYield 11.2%

Reagents, catalysts & solvents 1

HCID 6342AcetonitrileSolvent

Procedure

Chloroacetic acid (9.5 g) is dissolved in 70 ml of acetonitrile, to which 10.1 g of triethylamine is portionwise added and further 12.9 g of 2-amino-5-chloropyrdine is added. The mixture is refluxed for 3 hours. After cooling, the precipitated 2-imino-5-chloro-1,2-dihydropyridin-1-ylacetic acid as crystals is collected by filtration and dried. The crystals are added to 40 ml of phosphorus oxychoride and refluxed for 5 hours. After cooling, the reaction mixture is poured into ice water and neutralized with aqueous ammonia. The precipitate collected by filtration is purified by silica gel chromatography(eluent: ethyl acetate) to give 2.1 g of the title compound as crystals. mp. 155°-156° C.

Workup

  1. additionis portionwise added
  2. temperatureThe mixture is refluxed for 3 hours
  3. temperatureAfter cooling
  4. filtrationthe precipitated 2-imino-5-chloro-1,2-dihydropyridin-1-ylacetic acid as crystals is collected by filtration
  5. customdried
  6. additionThe crystals are added to 40 ml of phosphorus oxychoride
  7. temperaturerefluxed for 5 hours
  8. temperatureAfter cooling
  9. additionthe reaction mixture is poured into ice water and neutralized with aqueous ammonia
  10. filtrationThe precipitate collected by filtration
  11. customis purified by silica gel chromatography(eluent

Sources & evidence

ORD record
ord-6af8c646c62d43c9b79b756a3afd39ad
Source dataset
uspto-grants-1991_05
Patent number
US05017212

Reaction notes

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