Toluene → Methyl 4,4-ethylenedioxy-1,2,3,4-tetrahydro-5,8-dimethoxynaphthalene-2-carboxylate

HRID 462619Notes

Reaction equation

HRID 462619 reaction equation
[CH3:1][O:2][C:3]1[CH:12]=[CH:11][C:10]([O:13][CH3:14])=[C:9]2[C:4]=1[C:5](=[O:19])[CH2:6][CH:7]([C:15]([O:17][CH3:18])=[O:16])[CH2:8]2.[C:20]1([CH3:26])C=CC=CC=1.CCCCCC.C1(C)C=CC(S(O)(=O)=[O:40])=CC=1>C(O)CO>[CH2:26]1[CH2:20][O:40][C:5]2([C:4]3[C:9](=[C:10]([O:13][CH3:14])[CH:11]=[CH:12][C:3]=3[O:2][CH3:1])[CH2:8][CH:7]([C:15]([O:17][CH3:18])=[O:16])[CH2:6]2)[O:19]1

Participants

6

Reactant 4

HCID 1140TolueneHCID 6101p-Toluenesulfonic acidHCID 8058HexaneHCID 12772827Methyl 5,8-dimethoxy-4-oxo-1,2,3,4-tetrahydronaphthalene-2-carboxylate

Product 1

HCID 13264135Methyl 4,4-ethylenedioxy-1,2,3,4-tetrahydro-5,8-dimethoxynaphthalene-2-carboxylateYield 61%

Reagents, catalysts & solvents 1

HCID 174Ethylene GlycolSolvent

Procedure

40 g of methyl rac-1,2,3,4-tetrahydro-5,8-dimethoxy-4-oxonaphthalene-2-carboxylate was added to a mixture of 800 ml of toluene, 800 ml of hexane, 30 ml of ethyleneglycol and 0.65 g of toluene-4-sulphonic acid. The mixture was heated under reflux for 24 hours using a Dean-Stark trap. The solution was cooled in an ice-bath and washed with three 124 ml portions of 10% potassium hydrogen carbonate solution and 200 ml of brine, dried and the solvent was evaporated. The residue was taken up in 200 ml of methanol at 70° C. and 0.5 g of a 50% dispersion of sodium hydride in mineral oil was added. The solution obtained was left to cool to room temperature and then cooled further in an ice-bath for 2 hours. The crystalline product was filtered off, washed with cold methanol and dried in vacuo. There were obtained 28.5 g (61%) of methyl rac-4,4-ethylenedioxy-1,2,3,4-tetrahydro-5,8-dimethoxynaphthalene-2-carboxylate in the form of colourless crystals of melting point 133°-134° C.

Workup

  1. temperatureThe mixture was heated
  2. temperatureunder reflux for 24 hours
  3. temperatureThe solution was cooled in an ice-bath
  4. washwashed with three 124 ml portions of 10% potassium hydrogen carbonate solution and 200 ml of brine
  5. customdried
  6. customthe solvent was evaporated
  7. customwas taken up in 200 ml of methanol at 70° C.
  8. addition0.5 g of a 50% dispersion of sodium hydride in mineral oil was added
  9. customThe solution obtained
  10. waitwas left
  11. temperaturecooled further in an ice-bath for 2 hours
  12. filtrationThe crystalline product was filtered off
  13. washwashed with cold methanol
  14. customdried in vacuo

Sources & evidence

ORD record
ord-abb191b8b07f40dbb009727f596e948d
Source dataset
uspto-grants-1985_05
Patent number
US04515969

Reaction notes

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