Piperonal → 1,3-Benzodioxole, 5-ethenyl-

HRID 848048Notes

Reaction equation

HRID 848048 reaction equation
[C:1](=O)([O-])[O-].[K+].[K+].[CH:7]1[C:12]([CH:13]=O)=[CH:11][C:10]2[O:15][CH2:16][O:17][C:9]=2[CH:8]=1>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1COCC1.C1OCCOCCOCCOCCOCCOC1>[CH2:16]1[O:17][C:9]2[CH:8]=[CH:7][C:12]([CH:13]=[CH2:1])=[CH:11][C:10]=2[O:15]1

Participants

6

Reactant 2

HCID 8438PiperonalHCID 11430Potassium Carbonate

Product 1

HCID 1389861,3-Benzodioxole, 5-ethenyl-Yield 90.4%

Reagents, catalysts & solvents 3

HCID 2855718-Crown-6CatalystHCID 74505Methyltriphenyliphosphonium bromideCatalystHCID 8028TetrahydrofuranSolvent

Procedure

To a stirred suspension of (methyl)triphenylphosphonium bromide (17.1 g, 48 mmol) and potassium carbonate (6.63 g, 48 mmol) in THF (200 ml) were added piperonal (6.0 g, 40 mmol) and 18-crown-6 (120 mg, 0.46 mmol). The mixture was heated to reflux under nitrogen and refluxed for 36 hours. The reaction mixture was cooled to room temperature, filtered and the filtrate evaporated to dryness at 15° C. The resulting solid was stirred in 100 ml cold diethylether to dissolve the desired product, then filtered to remove inorganic salts, and the filtrate evaporated at 15° C. This process was repeated a second time. The product was filtered through 60 g basic alumina (pentane/ether, 24/l) and the solvent removed as before to give 5.36 g (89%) of the liquid styrene. NMR (CDCl3)δ6.89 (1H, singlet), 6.70-6.74 (2H, 2 overlapping singlets), 6.43-6.7 (1H, partially obscured doublet), 5.84 (2H, singlet), 5.50 (1H, doublet), 5.06 (1H, doublet).

Workup

  1. temperatureThe mixture was heated
  2. temperatureto reflux under nitrogen
  3. temperaturerefluxed for 36 hours
  4. filtrationfiltered
  5. customthe filtrate evaporated to dryness at 15° C
  6. dissolutionto dissolve the desired product
  7. filtrationfiltered
  8. customto remove inorganic salts
  9. customthe filtrate evaporated at 15° C
  10. filtrationThe product was filtered through 60 g basic alumina (pentane/ether, 24/l)
  11. customthe solvent removed as before

Sources & evidence

ORD record
ord-475ff4d58248496192e680fa0081c6cc
Source dataset
uspto-grants-1981_10
Patent number
US04294763

Reaction notes

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