1,2-Dibromoethane → 6-Methyl-2,3-dihydro-1,4-benzodioxine

HRID 395250Notes

Reaction equation

HRID 395250 reaction equation
[CH3:1][C:2]1[CH:3]=[C:4]([OH:9])[C:5](=[CH:7][CH:8]=1)[OH:6].Br[CH2:11][CH2:12]Br.C([O-])([O-])=O.[K+].[K+]>C(O)CO.[I-].[Na+]>[CH3:1][C:2]1[CH:8]=[CH:7][C:5]2[O:6][CH2:11][CH2:12][O:9][C:4]=2[CH:3]=1

Participants

6

Reactant 3

HCID 78391,2-DibromoethaneHCID 99584-MethylcatecholHCID 11430Potassium Carbonate

Product 1

HCID 124003766-Methyl-2,3-dihydro-1,4-benzodioxineYield 50%

Reagents, catalysts & solvents 2

HCID 5238Sodium IodideCatalystHCID 174Ethylene GlycolSolvent

Conditions

Temperature
130 °C

Procedure

A mixture of 4-methylcatechol (33.04 g, 266.1 mmol), 1,2-dibromoethane (100 g, 532.3 mmol), K2CO3 (75.4 g, 545.5 mmol) and sodium iodide (0.2 g, 1.33 mmol) in ethylene glycol (500 mL) was heated to 130° C. under nitrogen for five hours. The solution was allowed to cool to ambient temperature and stirred overnight. After the mixture was filtered through celite, the solution was diluted with brine (800 mL) and extracted with organic solvents (CH2Cl2/hexane/EtOAc: 1:3:1,3×500 mL). The organic layer was dried over Na2SO4, filtered and concentrated to provide a crude oil. Flash silica gel chromatography eluting with hexane (100%) gradient to ether/hexane (8:2) afforded the title intermediate as a colorless oil 20.0 g (50%).

Workup

  1. temperatureto cool to ambient temperature
  2. filtrationAfter the mixture was filtered through celite
  3. additionthe solution was diluted with brine (800 mL)
  4. extractionextracted with organic solvents (CH2Cl2/hexane/EtOAc: 1:3:1,3×500 mL)
  5. dry with materialThe organic layer was dried over Na2SO4
  6. filtrationfiltered
  7. concentrationconcentrated
  8. customto provide a crude oil
  9. washFlash silica gel chromatography eluting with hexane (100%) gradient to ether/hexane (8:2)

Sources & evidence

ORD record
ord-36989a97950047ca804b9329f2cd9f52
Source dataset
uspto-grants-2003_08
Patent number
US06605596B2

Reaction notes

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