Chlorine → 3-Chloro-2-methyl-8-pivaloylaminoimidazo[1,2-a]pyridine

HRID 1955003Notes

Reaction equation

HRID 1955003 reaction equation
Cl.[CH3:2][C:3]1[N:4]=[C:5]2[C:10]([NH:11][C:12](=[O:17])[C:13]([CH3:16])([CH3:15])[CH3:14])=[CH:9][CH:8]=[CH:7][N:6]2[CH:18]=1.NC1C2N(C=C(C)N=2)C=CC=1.C([Cl:36])(=O)C(C)(C)C.ClCl>C(O)(=O)C>[Cl:36][C:18]1[N:6]2[CH:7]=[CH:8][CH:9]=[C:10]([NH:11][C:12](=[O:17])[C:13]([CH3:15])([CH3:14])[CH3:16])[C:5]2=[N:4][C:3]=1[CH3:2]

Participants

6

Reactant 4

HCID 24526ChlorineHCID 62493Pivaloyl chlorideHCID 218739432-Methylimidazo[1,2-a]pyridin-8-amineHCID 232941602-Methyl-8-pivaloylaminoimidazo[1,2-a]pyridine hydrochloride

Product 1

HCID 232941713-Chloro-2-methyl-8-pivaloylaminoimidazo[1,2-a]pyridineYield 83%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

5.0 g (18.6 mmol) of 2-methyl-8-pivaloylaminoimidazo[1,2-a]pyridine hydrochloride, prepared from 8-amino-2-methylimidazo[1,2-a]pyridine and pivaloyl chloride, m.p. 229-230° C., are dissolved in glacial acetic acid (20 ml) and chlorine gas is slowly passed in at 15° C. until the reaction has ended according to TLC checking (about 20 min). The solvent is then distilled off, the residue is taken up in ethyl acetate/water (in each case 30 ml), and the solution is rendered basic and extracted with saturated sodium hydrogen carbonate solution. The extract is then extracted again with ethyl acetate (3×30 ml). The combined organic extracts are washed with water (50 ml), dried over magnesium sulfate and concentrated. The residue is purified by chromatography on silica gel (eluent: toluene/dioxane=9:1). After concentration of the fractions of Rf =0.2, the title compound (4.1 g, 83%) is obtained as a colorless solid. M.p. 117-118° C.

Workup

  1. customis slowly passed in at 15° C. until the reaction
  2. customhas ended according to TLC checking (about 20 min)
  3. distillationThe solvent is then distilled off
  4. extractionextracted with saturated sodium hydrogen carbonate solution
  5. extractionThe extract is then extracted again with ethyl acetate (3×30 ml)
  6. washThe combined organic extracts are washed with water (50 ml)
  7. dry with materialdried over magnesium sulfate
  8. concentrationconcentrated
  9. customThe residue is purified by chromatography on silica gel (eluent: toluene/dioxane=9:1)

Sources & evidence

ORD record
ord-ca732d7526a24b3384b4d75248937de6
Source dataset
uspto-grants-2000_09
Patent number
US06124313

Reaction notes

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