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

HRID 1640026Notes

Reaction equation

HRID 1640026 reaction equation
[CH3:1][C:2]1[CH:3]=[C:4]([OH:9])[C:5]([OH:8])=[CH:6][CH:7]=1.C(=O)([O-])[O-].[K+].[K+].Br[CH2:17][CH2:18]Br>CC(C)=O>[CH3:1][C:2]1[CH:7]=[CH:6][C:5]2[O:8][CH2:17][CH2:18][O:9][C:4]=2[CH:3]=1

Participants

5

Reactant 3

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

Product 1

HCID 124003766-Methyl-2,3-dihydro-1,4-benzodioxineYield 54%

Reagents, catalysts & solvents 1

HCID 180AcetoneSolvent

Procedure

A mixture of 4-methylbenzene-1,2-diol (10.0 g, 80.5 mmol) and potassium carbonate (111.3 g, 805.0 mmol) in acetone (300 mL) was stirred at room temperature for 1 h. After this time, 1,2-dibromoethane (27.7 mL, 322.0 mmol) was added and the reaction stirred at reflux for 5 d. After this time, the solvents were removed under reduced pressure and the solids redissolved in water (500 mL). The aqueous layer was then extracted three times with ethyl acetate (200 mL). The combined organic extracts were then dried over magnesium sulfate, filtered, and concentrated under reduced pressure. Purification by flash chromatography (silica, 1:20 ethyl acetate/hexanes) afforded 6-methyl-2,3-dihydrobenzo[b][1,4]dioxine (6.4 g, 54%) as a green oil: 1H NMR (500 MHz, CDCl3) δ 6.74 (d, J=8.5 Hz, 1H), 6.67 (d, J=2.0 Hz, 1H), 6.63 (dd, J 2.0, 8.0 Hz, 1H), 4.22 (m, 4H), 2.24 (s, 3H).

Workup

  1. stirringthe reaction stirred
  2. temperatureat reflux for 5 d
  3. customAfter this time, the solvents were removed under reduced pressure
  4. dissolutionthe solids redissolved in water (500 mL)
  5. extractionThe aqueous layer was then extracted three times with ethyl acetate (200 mL)
  6. dry with materialThe combined organic extracts were then dried over magnesium sulfate
  7. filtrationfiltered
  8. concentrationconcentrated under reduced pressure
  9. customPurification by flash chromatography (silica, 1:20 ethyl acetate/hexanes)

Sources & evidence

ORD record
ord-731b193a238a42fc9d92b2b02dc1ea55
Source dataset
uspto-grants-2012_02
Patent number
US08110681B2

Reaction notes

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