2-Bromopropene → Isoprene 5-isopropenyl-6-methoxy-2,3-dihydro-benzo[1,4]dioxine

HRID 1677301Notes

Reaction equation

HRID 1677301 reaction equation
Br[C:2]([CH3:4])=[CH2:3].[CH3:5][O:6][C:7]1[CH:16]=[CH:15][C:10]2[O:11][CH2:12][CH2:13][O:14][C:9]=2[C:8]=1B(O)O.[C:20]([O-])([O-])=O.[K+].[K+]>COCCOC.C1C=CC([P]([Pd]([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)[P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1>[C:2]([C:8]1[C:9]2[O:14][CH2:13][CH2:12][O:11][C:10]=2[CH:15]=[CH:16][C:7]=1[O:6][CH3:5])([CH3:4])=[CH2:3].[CH2:10]=[CH:15][C:16](=[CH2:7])[CH3:20]

Participants

6

Reactant 3

HCID 112022-BromopropeneHCID 11430Potassium CarbonateHCID 225718926-Methoxy-2,3-dihydro-benzo[1,4]dioxin-5-yl-boronic acid

Product 1

HCID 86600725Isoprene 5-isopropenyl-6-methoxy-2,3-dihydro-benzo[1,4]dioxine

Reagents, catalysts & solvents 2

HCID 178418397HCID 178418397, compoundCatalystHCID 80711,2-DimethoxyethaneSolvent

Procedure

To a solution of 2-bromopropene (5.4 ml, 59 mmol) in 200 mL DME was added Pd(Ph3P)4 (3.116, 2.8 mmol). After 30 min 6-methoxy-2,3-dihydro-benzo[1,4]dioxin-5-yl-boronic acid (13.320 g, 58.6 mmol) and K2CO3 (8.099 g, 58.6 mmol) was added. The mixture was warmed to reflux. After 16 hours the mixture was cooled, filtered through a pad of celite and concentrated in vacuo. The residue was dissolved in H2O and extracted with ethyl acetate. The combined organics were washed with saturated NaHCO3, dried over MgSO4, filtered and concentrated in vacuo. Purification via flash chromatography afforded isoprene 5-isopropenyl-6-methoxy-2,3-dihydro-benzo[1,4]dioxine (5.542 g, as an inseparable mixture of product/sm 1:1) as an oil.

Workup

  1. temperatureThe mixture was warmed to reflux
  2. temperatureAfter 16 hours the mixture was cooled
  3. filtrationfiltered through a pad of celite
  4. concentrationconcentrated in vacuo
  5. dissolutionThe residue was dissolved in H2O
  6. extractionextracted with ethyl acetate
  7. washThe combined organics were washed with saturated NaHCO3
  8. dry with materialdried over MgSO4
  9. filtrationfiltered
  10. concentrationconcentrated in vacuo
  11. customPurification via flash chromatography

Sources & evidence

ORD record
ord-4e67b923372341e3b55d5104e2797345
Source dataset
uspto-grants-2011_08
Patent number
US08008313B2

Reaction notes

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