Oxygen → Methyl rac-4,4-ethylenedioxy-1,2,3,4-tetrahydro-2-hydroxy-5,8-dimethoxynaphthalene-2-carboxylate

HRID 280907Notes

Reaction equation

HRID 280907 reaction equation
[CH2:1]1[CH2:22][O:21][C:3]2([C:12]3[C:7](=[C:8]([O:15][CH3:16])[CH:9]=[CH:10][C:11]=3[O:13][CH3:14])[CH2:6][CH:5]([C:17]([O:19][CH3:20])=[O:18])[CH2:4]2)[O:2]1.C([O:25]P(OCC)OCC)C.O=O>O1CCCC1.CCOCC>[CH2:22]1[CH2:1][O:2][C:3]2([C:12]3[C:7](=[C:8]([O:15][CH3:16])[CH:9]=[CH:10][C:11]=3[O:13][CH3:14])[CH2:6][CH:5]([C:17]([O:19][CH3:20])=[O:18])[CH2:4]2)[O:21]1.[CH2:22]1[CH2:1][O:2][C:3]2([C:12]3[C:7](=[C:8]([O:15][CH3:16])[CH:9]=[CH:10][C:11]=3[O:13][CH3:14])[CH2:6][C:5]([OH:25])([C:17]([O:19][CH3:20])=[O:18])[CH2:4]2)[O:21]1

Participants

7

Reactant 3

HCID 977Oxygen2×HCID 31215Triethyl phosphiteHCID 13264135Methyl 4,4-ethylenedioxy-1,2,3,4-tetrahydro-5,8-dimethoxynaphthalene-2-carboxylate

Product 2

HCID 13264135Methyl 4,4-ethylenedioxy-1,2,3,4-tetrahydro-5,8-dimethoxynaphthalene-2-carboxylateHCID 13264136Methyl rac-4,4-ethylenedioxy-1,2,3,4-tetrahydro-2-hydroxy-5,8-dimethoxynaphthalene-2-carboxylateYield 66%

Reagents, catalysts & solvents 2

HCID 3283Diethyl EtherSolventHCID 8028TetrahydrofuranSolvent2×

Procedure

(ii)(b) A solution of the lithium enolate of methyl rac-4,4-ethylenedioxy-1,2,3,4-tetrahydro-5,8-dimethoxy-naphthalene-2-carboxylate was prepared in tetrahydrofuran as described in part (ii)(a) hereinbefore from 9.84 g of methyl rac-4,4-ethylenedioxy-1,2,3,4-tetrahydro-5,8-dimethoxynaphthalene-2-carboxylate. The enolate was added over a period of 5 minutes at -78° C. to a stirred solution of 11.2 ml of dry triethylphosphite in 60 ml of tetrahydrofuran through which a rapid stream of oxygen was passing. The passage of oxygen was maintained for 50 minutes and the temperature was held at -78° C. The reaction was then quenched by the addition of 8.8 ml of acetic acid. The cooling bath was removed and, after 5 minutes, 200 ml of water were added. After a further 20 minutes, most of the tetrahydrofuran was evaporated and the product was extracted into four 100 ml portions of ethyl acetate. The combined ethyl acetate extracts were washed with 200 ml of 10% aqueous potassium hydrogen carbonate, dried over magnesium sulphate, filtered and evaporated to give a yellow oil which was dissolved in 130 ml of ether and left to crystallise. There were obtained 6.86 g (66%) of methyl rac-4,4-ethylenedioxy-1,2,3,4-tetrahydro-2-hydroxy-5,8-dimethoxynaphthalene-2-carboxylate in the form of colourless crystals of melting point 74°-75° C.

Workup

  1. customwas held at -78° C
  2. customThe reaction was then quenched by the addition of 8.8 ml of acetic acid
  3. customThe cooling bath was removed and, after 5 minutes
  4. addition200 ml of water were added
  5. custommost of the tetrahydrofuran was evaporated
  6. extractionthe product was extracted into four 100 ml portions of ethyl acetate
  7. washThe combined ethyl acetate extracts were washed with 200 ml of 10% aqueous potassium hydrogen carbonate
  8. dry with materialdried over magnesium sulphate
  9. filtrationfiltered
  10. customevaporated
  11. customto give a yellow oil which
  12. waitleft
  13. customto crystallise

Sources & evidence

ORD record
ord-b8f06198f1d340bf8c10befab22b433d
Source dataset
uspto-grants-1986_05
Patent number
US04591636

Reaction notes

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