Allyl bromide → 2H-1-Benzopyran-2-one, 4,8-dimethyl-7-(2-propen-1-yloxy)-

HRID 1587049Notes

Reaction equation

HRID 1587049 reaction equation
[CH3:1][C:2]1[C:11]2[C:6](=[C:7]([CH3:13])[C:8]([OH:12])=[CH:9][CH:10]=2)[O:5][C:4](=[O:14])[CH:3]=1.Br[CH2:16][CH:17]=[CH2:18].C(=O)([O-])[O-].[K+].[K+]>CC(C)=O>[CH3:1][C:2]1[C:11]2[C:6](=[C:7]([CH3:13])[C:8]([O:12][CH2:18][CH:17]=[CH2:16])=[CH:9][CH:10]=2)[O:5][C:4](=[O:14])[CH:3]=1

Participants

5

Reactant 3

HCID 7841Allyl bromideHCID 11430Potassium CarbonateHCID 53565972H-1-Benzopyran-2-one, 7-hydroxy-4,8-dimethyl-

Product 1

HCID 962252H-1-Benzopyran-2-one, 4,8-dimethyl-7-(2-propen-1-yloxy)-Yield 60%

Reagents, catalysts & solvents 1

HCID 180AcetoneSolvent

Procedure

A solution of 4,8-dimethyl-7-hydroxycoumarin (4.85 g, 25.5 mmoles) in 200 ml of acetone was reacted with 3-bromopropene (4.62 g, 38.2 mmoles) in the presence of anhydrous potassium carbonate (10 g). The reaction mixture was heated under reflux for 4 hours, cooled and filtered. The collected solid was washed with fresh acetone. The filtrate and washings were combined and the solvent evaporated under reduced pressure. The crude product was recrystallized from methanol to yield the title compound as fluffy, white needles, m.p. 107°-108° C., 3.5 g, 60% yield. 1H NMR: 2.3 (s, 3H, C8 --CH3), 2.4 (d, 3H, C4 --CH3J=1.2 Hz), 4.6 (dt, 2H, O--CH2J=1.5, 4.8 Hz), 5.4 (m, 2H, =CH2J=4.8 Hz), 5.9 (m, 1H, --CH=CH2), 6.1 (d, 1H, C3 --H, J=1.2 Hz), 6.8 (d, 1H, C6 --H, J=9.0 Hz), 7.3 (d, 1H, C5 --H, J=9.0 Hz)

Workup

  1. temperatureThe reaction mixture was heated
  2. temperatureunder reflux for 4 hours
  3. temperaturecooled
  4. filtrationfiltered
  5. washThe collected solid was washed with fresh acetone
  6. customthe solvent evaporated under reduced pressure
  7. customThe crude product was recrystallized from methanol

Sources & evidence

ORD record
ord-40d7c9b5c04245e1bf46d4e7de9ee554
Source dataset
uspto-grants-1993_06
Patent number
US05216176

Reaction notes

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