Hydrochloric Acid → 8-bromo-3-methylquinoxalin-2(1H)-one

HRID 1055952Notes

Reaction equation

HRID 1055952 reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][CH:5]=[C:6]2[C:11]=1[NH:10][C:9](=[O:12])[C@H:8]([CH3:13])[NH:7]2.[OH-].[Na+].OO.Cl>O.CO>[Br:1][C:2]1[CH:3]=[CH:4][CH:5]=[C:6]2[C:11]=1[NH:10][C:9](=[O:12])[C:8]([CH3:13])=[N:7]2

Participants

7

Reactant 4

HCID 313Hydrochloric AcidHCID 784Hydrogen PeroxideHCID 14798Sodium HydroxideHCID 89793650(S)-8-bromo-3-methyl-3,4-dihydroquinoxalin-2(1H)-one

Product 1

HCID 712955428-bromo-3-methylquinoxalin-2(1H)-oneYield 78.2%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 962WaterSolvent

Conditions

Temperature
85 °C

Procedure

A solution of (S)-8-bromo-3-methyl-3,4-dihydroquinoxalin-2(1H)-one (17 g, 70.5 mmol), MeOH (141 mL), and 1.0 N aq. NaOH (141 mL, 141 mmol) was stirred at 85° C. in a three-necked round-bottom flask fitted with a septum, reflux condenser, and addition funnel. A mixture of H2O2 (30% in water; 25.2 mL, 247 mmol) and deionized water (10 mL) was then added, dropwise via the addition funnel, over 45 min, and the resulting mixture was heated at 85° C. for 17 h. The mixture was cooled to RT, 5 N aq. HCl (36 mL) was added, and the resulting slurry was extracted with 10% MeOH/DCM (3×150 mL). The combined extracts were dried over Na2SO4, filtered, and concentrated in vacuo to give 8-bromo-3-methylquinoxalin-2(1H)-one (126d; 13.16 g, 55.1 mmol, 78% yield) as a tan solid, which was used without further purification in the subsequent step: 1H NMR (400 MHz, CDCl3) δ ppm 9.03 (1H, s), 7.77 (1H, d, J=8.2 Hz), 7.67 (1H, d, J=7.6 Hz), 7.22 (1H, t, J=7.8 Hz), 2.61 (3H, s). m/z (ESI, +ve) 239.0 (M+H)+.

Workup

  1. customfitted with a septum
  2. temperaturereflux
  3. additioncondenser, and addition funnel
  4. additionwas then added, dropwise via the addition funnel, over 45 min
  5. temperatureThe mixture was cooled to RT
  6. extractionthe resulting slurry was extracted with 10% MeOH/DCM (3×150 mL)
  7. dry with materialThe combined extracts were dried over Na2SO4
  8. filtrationfiltered
  9. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-da34d7287057493c949cb899fa35ad6b
Source dataset
uspto-grants-2016_07
Patent number
US09394297B2

Reaction notes

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