1,1-Dibromoethane → 2H-1,4-Benzoxazine, 3,4-dihydro-4-methyl-

HRID 970318Notes

Reaction equation

HRID 970318 reaction equation
[CH3:1][NH:2][C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][C:4]=1[OH:9].Br[CH:11](Br)[CH3:12].C(=O)([O-])[O-].[K+].[K+]>CC(C)=O.O>[CH3:1][N:2]1[C:3]2[CH:8]=[CH:7][CH:6]=[CH:5][C:4]=2[O:9][CH2:12][CH2:11]1

Participants

6

Reactant 3

HCID 112011,1-DibromoethaneHCID 11430Potassium CarbonateHCID 69138o-(Methylamino)phenol

Product 1

HCID 37550242H-1,4-Benzoxazine, 3,4-dihydro-4-methyl-Yield 79%

Reagents, catalysts & solvents 2

HCID 180AcetoneSolventHCID 962WaterSolvent

Procedure

To a mixture of 104A (2.33 g, 18.9 mmol) and dibromoethane (6.5 mL, 75.7 mmol) in a mixture of acetone (80 mL) and water (20 mL) at room temperature was added potassium carbonate (10.46 g, 75.7 mmol). The mixture was heated at reflux for 3 days. HPLC indicated that the reaction was complete, and the acetone was removed under reduced pressure. The aqueous residue was extracted with DCM, washed with water, and dried over anhydrous sodium sulfate. Concentration under reduced pressure followed by purification by silica gel chromatography afforded 104B (2.22 g, 79%). HPLC retention time=2.07 min. (Condition B) and LC/MS M+1=150.08. 1H-NMR (500 MHz, CDCl3) δ 2.91 (s, 3H), 3.28 (t, 2H), 4.33 (t, 2H), 6.70 (t, 1H, J=7.5 Hz), 6.72 (d, 1H, J=7.5 Hz), 6.82 (d, 1H, J=7.5 Hz), and 6.89 (t, 1H, J=7.5 Hz).

Workup

  1. temperatureThe mixture was heated
  2. temperatureat reflux for 3 days
  3. customthe acetone was removed under reduced pressure
  4. extractionThe aqueous residue was extracted with DCM
  5. washwashed with water
  6. dry with materialdried over anhydrous sodium sulfate
  7. concentrationConcentration under reduced pressure
  8. customfollowed by purification by silica gel chromatography

Sources & evidence

ORD record
ord-95b64d6cec094887a8203eb207abaaa8
Source dataset
uspto-grants-2007_12
Patent number
US07312209B2

Reaction notes

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