2-Aminopyridine → 2-(2-Nitrophenyl)imidazo[1,2-a]pyridine

HRID 416656Notes

Reaction equation

HRID 416656 reaction equation
Br[CH2:2][C:3]([C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][C:6]=1[N+:11]([O-:13])=[O:12])=O.[NH2:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][N:16]=1>CC(C)=O>[N+:11]([C:6]1[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=1[C:3]1[N:14]=[C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][N:16]2[CH:2]=1)([O-:13])=[O:12]

Participants

4

Reactant 2

HCID 104392-AminopyridineHCID 2440252-Bromo-2'-nitroacetophenone

Product 1

HCID 596799982-(2-Nitrophenyl)imidazo[1,2-a]pyridineYield 74%

Reagents, catalysts & solvents 1

HCID 180AcetoneSolvent

Procedure

2-Bromo-2′-nitroacetophenone (7.65 g, 31.3 mmol) and 2-aminopyridine (2.95 g, 31.3 mmol) were dissolved in acetone (50 ml) and brought to reflux. After 10 minutes a light yellow/white precipitate forms in addition to strong boiling. Refluxing was continued for 3 hours and cooled to room temperature. The volume was reduced ½ by evaporation and the intermediate solids were collected by filtration and washed with acetone (20 ml) and air dried (7.26 g of intermediate). The intermediate (7.20 g) was dissolved in MeOH (100 ml) with HBr (4 drops, catalytic) and brought to reflux. The reaction was monitored by TLC (10% MeOH in CH2Cl2). After 70 minutes, the reaction mixture was cooled to room temperature, adjusted to pH=12 with 1M NaOH, and concentrated to remove the methanol. The yellow product was collected by filtration, washed with water and air dried. 5.54 g (74%) of 2-(2-Nitro-phenyl)-imidazo[1,2-a]pyridine was obtained as a yellow crystalline solid (MS, M++H=240.1).

Workup

  1. temperatureto reflux
  2. additionAfter 10 minutes a light yellow/white precipitate forms in addition to strong boiling
  3. temperatureRefluxing
  4. customby evaporation
  5. filtrationthe intermediate solids were collected by filtration
  6. washwashed with acetone (20 ml) and air
  7. dry with materialdried (7.26 g of intermediate)
  8. dissolutionThe intermediate (7.20 g) was dissolved in MeOH (100 ml) with HBr (4 drops, catalytic)
  9. temperatureto reflux
  10. waitAfter 70 minutes
  11. temperaturethe reaction mixture was cooled to room temperature
  12. concentrationconcentrated
  13. customto remove the methanol
  14. filtrationThe yellow product was collected by filtration
  15. washwashed with water and air
  16. customdried

Sources & evidence

ORD record
ord-4e6b9a5b0e2a4291aafe4016338fbf1a
Source dataset
uspto-grants-2012_01
Patent number
US08088928B2

Reaction notes

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