5-Methoxytetralone → 5-Methoxy-1-methylene-1,2,3,4-tetrahydronaphthalene

HRID 2276301Notes

Reaction equation

HRID 2276301 reaction equation
[CH3:1][O:2][C:3]1[CH:12]=[CH:11][CH:10]=[C:9]2[C:4]=1[CH2:5][CH2:6][CH2:7][C:8]2=O.[I-].[CH3:15][P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.CC(C)([O-])C.[K+]>C1COCC1>[CH3:1][O:2][C:3]1[CH:12]=[CH:11][CH:10]=[C:9]2[C:4]=1[CH2:5][CH2:6][CH2:7][C:8]2=[CH2:15]

Participants

5

Reactant 3

HCID 366205-MethoxytetraloneHCID 638159Methyltriphenylphosphonium iodideHCID 23665647Potassium tert-butoxide

Product 1

HCID 116080075-Methoxy-1-methylene-1,2,3,4-tetrahydronaphthaleneYield 99%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

To a slurry of 5-Methoxy-3,4-dihydro-2H-naphthalen-1-one (25 g, 0.14 mol) and methyltriphenylphosphonium iodide (1.13 eq) in THF (250 mL) at RT was added potassium t-butoxide (1.6 eq) at such a rate as to maintain a temperature no higher than warm to the touch. The reaction was stirred for one hour and concentrated. The reaction was then azeotroped with three volumes of hexane to remove excess t-butanol. Fresh hexane was added the solution was let to stand overnight to effect trituration. The red-brown solid was removed by filtration and the filtrate was washed twice with water and was concentrated. Purification by chromatography on ISCO (330 g SiO2 cartridge: stepwise hexane and then DCM) affords the title compound as a pale yellow oil (24 g, 99%). 1H-NMR (400 MHz, CDCl3) 7.29 (d, J=8.0 Hz, 1H), 7.15 (t, J=8.0 Hz, 1H), 6.76 (d, J=8.0 Hz, 1H), 5.49 (s, 1H), 4.98 (s, 1H), 3.85 (s, 3H), 2.77 (t, J=6.4 Hz, 2H), 2.53-2.50 (m, 2H), 1.93-1.87 (m, 2H).

Workup

  1. temperatureto maintain a temperature no higher
  2. temperaturethan warm to the touch
  3. concentrationconcentrated
  4. customThe reaction was then azeotroped with three volumes of hexane
  5. customto remove excess t-butanol
  6. additionFresh hexane was added the solution
  7. waitto stand overnight
  8. customThe red-brown solid was removed by filtration
  9. washthe filtrate was washed twice with water
  10. concentrationwas concentrated
  11. customPurification by chromatography on ISCO (330 g SiO2 cartridge

Sources & evidence

ORD record
ord-80d96e0421f4449e8b474ade903fe510
Source dataset
uspto-grants-2015_09
Patent number
US09132128B2

Reaction notes

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