Acetic Acid → Ethyl 2-methyl-4-oxocyclopent-2-ene-1-carboxylate

HRID 2204566Notes

Reaction equation

HRID 2204566 reaction equation
[CH2:1]([O:3][C:4]([C:6]1[CH2:10][C:9]([O-:11])=[C:8](C(OC)=O)[C:7]=1[CH3:16])=[O:5])[CH3:2].[Na+].CC(O)=O.[I-].[Na+]>COCCOCCOC>[CH3:16][C:7]1[CH:6]([C:4]([O:3][CH2:1][CH3:2])=[O:5])[CH2:10][C:9](=[O:11])[CH:8]=1

Participants

5

Reactant 3

HCID 176Acetic AcidHCID 5238Sodium IodideHCID 58010173Sodium 4-(ethoxycarbonyl)-2-(methoxycarbonyl)-3-methylcyclopenta-1,3-dienolate

Product 1

HCID 11332690Ethyl 2-methyl-4-oxocyclopent-2-ene-1-carboxylateYield 57.5%

Reagents, catalysts & solvents 1

HCID 8150DiglymeSolvent

Procedure

A round-bottom flask was charged with sodium 4-(ethoxycarbonyl)-2-(methoxycarbonyl)-3-methylcyclopenta-1,3-dienolate (105 g, 0.420 mol) and diglyme (1 L) to give a yellow suspension. AcOH (100 mL, 1.7 mol) was added to the resulting mixture and sodium iodide (280 g, 1.9 mol) was added portion-wise over about 5-10 min. The reaction mixture was then heated to reflux for about 3 h, cooled to room temperature, and poured over ice water (800 mL). The resulting material was extracted with Et2O (3×500 mL). The combined organic extracts were washed with brine (2×500 mL), dried over anhydrous MgSO4, and filtered. The solvent was removed under reduced pressure to give a brown liquid that was purified by vacuum distillation (80-85° C., 0.3 Torr) to give ethyl 2-methyl-4-oxocyclopent-2-enecarboxylate (40.6 g, 57%) as a yellow oil: 1H NMR (CDCl3) δ 6.06-5.98 (m, 1H), 4.30-4.11 (m, 2H), 3.72-3.65 (m, 1H), 2.77-2.66 (m, 1H), 2.66-2.57 (m, 1H), 2.17 (s, 3H), 1.30 (t, J=7.1 Hz, 3H).

Workup

  1. customto give a yellow suspension
  2. additionwas added portion-wise over about 5-10 min
  3. temperatureThe reaction mixture was then heated
  4. temperatureto reflux for about 3 h
  5. extractionThe resulting material was extracted with Et2O (3×500 mL)
  6. washThe combined organic extracts were washed with brine (2×500 mL)
  7. dry with materialdried over anhydrous MgSO4
  8. filtrationfiltered
  9. customThe solvent was removed under reduced pressure
  10. customto give a brown liquid that
  11. distillationwas purified by vacuum distillation (80-85° C., 0.3 Torr)

Sources & evidence

ORD record
ord-23b22eb969564ae6a2d2b648f75f18a0
Source dataset
uspto-grants-2016_06
Patent number
US09365579B2

Reaction notes

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