8-Methoxypsoralen → 4-Bromo-9-methoxy-7h-furo[3,2-g]chromen-7-one

HRID 581209Notes

Reaction equation

HRID 581209 reaction equation
[CH3:1][O:2][C:3]1[C:11]2[O:12][C:13]([CH:15]=[CH:16][C:10]=2[CH:9]=[C:5]2[CH:6]=[CH:7][O:8][C:4]=12)=[O:14].[Br:17]Br>O1CCCC1>[CH3:1][O:2][C:3]1[C:11]2[O:12][C:13]([CH:15]=[CH:16][C:10]=2[C:9]([Br:17])=[C:5]2[CH:6]=[CH:7][O:8][C:4]=12)=[O:14]

Participants

4

Reactant 2

HCID 41148-MethoxypsoralenHCID 24408Bromine2×

Product 1

HCID 2400484-Bromo-9-methoxy-7h-furo[3,2-g]chromen-7-oneYield 91.2%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

8-methoxypsoralen (4.32 g, 20.0 mmol), obtained from Aldrich Chemical Company was dissolved in tetrahydrofuran (50 mL). To the mixture was added dropwise, with stirring, elemental bromine (4.0 g, 25 mmol) over 20 min at room temperature. The reaction mixture turned red when bromine was added. Precipitate appeared in 5 min. Extra bromine was consumed by solvent tetrahydrofuran in an extended 2 hr stirring or by the addition of 10% sodium thiosulfate solution. The crude product was collected by filtration and was purified with recrystallization from ethanol to give the product 5-bromo-8-methoxypsoralen (5.38 g, 91% yield) as a white solid. mp 178-80° C. 1H--NMR (DMSO(dimethylsulfoxide)--d6, ppm): 8.22(d, J=2.2 Hz, 1H), 8.11 (d, J=9.9 Hz, 1H),7.01(d,J=2.2 Hz, 1H),6.53(d, J=9.9 Hz, 1H),4.17(s,3H).

Workup

  1. additionTo the mixture was added dropwise
  2. additionwas added
  3. customExtra bromine was consumed by solvent tetrahydrofuran in an extended 2 hr
  4. stirringstirring or by the addition of 10% sodium thiosulfate solution
  5. filtrationThe crude product was collected by filtration
  6. customwas purified with recrystallization from ethanol

Sources & evidence

ORD record
ord-a583aa25c2164dd0916f6b0636124b53
Source dataset
uspto-grants-1999_07
Patent number
US05919935

Reaction notes

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