1,2-Dibromoethane → 5-Bromo-7-chloro-2,3-dihydro-1,4-benzodioxin

HRID 2100355Notes

Reaction equation

HRID 2100355 reaction equation
Br[CH2:2][CH2:3]Br.[Br:5][C:6]1[CH:11]=[C:10]([Cl:12])[CH:9]=[C:8]([OH:13])[C:7]=1[OH:14].[OH-].[Na+]>[Br-].C([N+](CCCC)(CCCC)CCCC)CCC.O>[Br:5][C:6]1[C:7]2[O:14][CH2:3][CH2:2][O:13][C:8]=2[CH:9]=[C:10]([Cl:12])[CH:11]=1

Participants

6

Reactant 3

HCID 78391,2-DibromoethaneHCID 14798Sodium HydroxideHCID 177610523-Bromo-5-chlorobenzene-1,2-diol

Product 1

HCID 577991545-Bromo-7-chloro-2,3-dihydro-1,4-benzodioxinYield 60%

Reagents, catalysts & solvents 2

HCID 74236Tetrabutylammonium BromideCatalystHCID 962WaterSolvent3×

Procedure

To a solution of 1,2-dibromoethane (1.44 ml, 16 mmol) and tetrabutylammonium bromide (96 mg, 2.5 mol %) in water (8 ml) at reflux under nitrogen was added a mixture of 3-bromo-5-chloro-benzene-1,2-diol (Preparation 21, 2.68 g, 12 mmol) and NaOH (1.06 g, 26.2 mmol) in water (10 ml) over 4 hours, and the resultant mixture stirred overnight. The reaction mixture was cooled to room temperature and diluted with water (100 ml). The mixture was extracted with Et2O (3×100 ml), and the combined organic extracts were concentrated in vacuo. Purification by flash chromatography (pentane:dichloromethane 9:1) afforded the desired product as a yellow oil (1.78 g, 60%) which crystallised on standing to a yellow solid.

Workup

  1. additionwas added
  2. extractionThe mixture was extracted with Et2O (3×100 ml)
  3. concentrationthe combined organic extracts were concentrated in vacuo
  4. customPurification by flash chromatography (pentane:dichloromethane 9:1)

Sources & evidence

ORD record
ord-d6fe813de54d4ffda046146d7fe5ea32
Source dataset
uspto-grants-2009_08
Patent number
US07572797B2

Reaction notes

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