Iodine → 1,3-Dihydro-7,8-dimethyl-2H-imidazo(4,5-b)quinolin-2-one

HRID 979527Notes

Reaction equation

HRID 979527 reaction equation
[CH3:1][C:2]1[C:7]([CH3:8])=[CH:6][CH:5]=[C:4]([N+:9]([O-])=O)[C:3]=1[CH:12]=[C:13]1[NH:17][C:16](=[O:18])[NH:15][C:14]1=O.[H][H].CO.II>CN(C)C=O.[Pd].O>[CH3:8][C:7]1[CH:6]=[CH:5][C:4]2[N:9]=[C:14]3[NH:15][C:16](=[O:18])[NH:17][C:13]3=[CH:12][C:3]=2[C:2]=1[CH3:1]

Participants

8

Reactant 4

HCID 807IodineHCID 887MethanolHCID 544700675-[(2,3-Dimethyl-6-nitrophenyl)methylidene]imidazolidine-2,4-dioneHCID 178418361HCID 178418361, compound

Product 1

HCID 54872811,3-Dihydro-7,8-dimethyl-2H-imidazo(4,5-b)quinolin-2-oneYield 329.5%

Reagents, catalysts & solvents 3

HCID 23938PalladiumCatalystHCID 962WaterSolventHCID 6228DimethylformamideSolvent

Procedure

5-[(2,3-Dimethyl-6-nitrophenyl)methylene]-2,4-imidazolidinedione (19.95 g, 76 mmol) in dimethylformamide (350 mL) was hydrogenated over 10% palladium on charcoal (3 g) at 60 p.s.i. in a Parr hydrogenation apparatus. After hydrogen uptake ceased, the mixture was filtered through kieselgehr and the solvent evaporated to leave a solid which was suspended in a refluxing methanol (1 L). Iodine (19.4 g, 76 mmol) was added portionwise over 5 minutes and the mixture refluxed for 15 minutes before being concentrated in vacuo to about 100 mL. A solution of sodium thiosulfate (21 g) and sodium carbonate (11 g) in water (300 mL) was added with vigorous stirring to afford a beige precipitate which was collected, washed with water and dried in air to give 15.7 g. This was combined with crude material from experiments performed on 40 g and 4.16 g of starting material, suspended in hot (80° C.) water, filtered, suspended in refluxing methanol and filtered. Crystallization from dimethylacetamide afforded 1,3-dihydro-7,8-dimethyl-2H-imidazo[4,5-b]quinolin-2-one (53.4 g, 65%), m.p. >300° C.

Workup

  1. filtrationthe mixture was filtered through kieselgehr
  2. customthe solvent evaporated
  3. customto leave a solid which
  4. temperaturethe mixture refluxed for 15 minutes
  5. concentrationbefore being concentrated in vacuo to about 100 mL
  6. additionA solution of sodium thiosulfate (21 g) and sodium carbonate (11 g) in water (300 mL) was added
  7. customto afford a beige precipitate which
  8. customwas collected
  9. washwashed with water
  10. customdried in air
  11. customto give 15.7 g
  12. filtrationfiltered
  13. temperaturein refluxing methanol
  14. filtrationfiltered
  15. customCrystallization from dimethylacetamide

Sources & evidence

ORD record
ord-24c55c322ad3441eb5f209a21e8b5ba8
Source dataset
uspto-grants-1987_05
Patent number
US04668686

Reaction notes

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