Ammonium Chloride → cis-Ethyl 4-hydroxy-2-methylcyclopent-2-enecarboxylate

HRID 1854370Notes

Reaction equation

HRID 1854370 reaction equation
[CH3:1][C:2]1[CH:3]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[CH2:4][C:5](=[O:7])[CH:6]=1.O.O.O.O.O.O.O.[Cl-].[Ce+3].[Cl-].[Cl-].[BH4-].[Na+].[NH4+].[Cl-]>CCOCC.CO>[OH:7][C@@H:5]1[CH2:4][C@H:3]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[C:2]([CH3:1])=[CH:6]1

Participants

7

Reactant 4

HCID 25517Ammonium ChlorideHCID 4311764Sodium borohydrideHCID 11332690Ethyl 2-methyl-4-oxocyclopent-2-ene-1-carboxylateHCID 21585214Cerium trichloride heptahydrate

Product 1

HCID 10877556cis-Ethyl 4-hydroxy-2-methylcyclopent-2-enecarboxylateYield 46.6%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 3283Diethyl EtherSolvent

Procedure

A round-bottom flask was charged with ethyl 2-methyl-4-oxocyclopent-2-enecarboxylate (2.04 g, 12.1 mmol, Preparation #CC.1), MeOH (30 mL), and cerium(III) chloride heptahydrate (5.65 g, 15.2 mmol) followed by portion-wise addition of sodium borohydride (0.574 g, 15.2 mmol). The suspension was stirred at room temperature over about 16 h. Saturated aqueous NH4Cl solution (50 mL) was added. The mixture was stirred for about 10 min and Et2O (60 mL) was added. The layers were separated and the aqueous layer was extracted with Et2O (3×30 mL). The combined organic layers were washed with saturated aqueous NaHCO3, dried over anhydrous MgSO4, filtered, and concentrated to dryness under reduced pressure. The residue was purified via silica gel chromatography eluting with 20-60% EtOAc/pentane to yield cis-ethyl 4-hydroxy-2-methylcyclopent-2-enecarboxylate (0.96 g, 46%): 1H NMR (400 MHz, CDCl3) δ 5.77-5.71 (m, 1H), 4.63 (m, 1H), 4.28-4.11 (m, 2H), 3.27-3.20 (m, 1H), 2.59 (bs, 1H), 2.41-2.30 (m, 1H), 2.00 (d, J=14.2 Hz, 1H), 1.79 (d,=1.2 Hz, 3H), 1.30 (t, J=7.1 Hz, 3H) and trans-ethyl 4-hydroxy-2-methylcyclopent-2-enecarboxylate (0.69 g, 33%): 1H NMR (400 MHz, CDCl3) δ 5.63 (dd, J=1.8, 3.4 Hz, 1H), 4.98 (m, 1H), 4.20-4.11 (m, 2H), 3.60-3.53 (m, 1H), 2.57 (ddd, J=4.4, 7.1, 13.9 Hz, 1H), 1.98 (ddd, J=3.5, 8.4, 13.9 Hz, 1H), 1.80 (d, J=1.4, 3H), 1.46 (bs, 1H), 1.27 (t, J=7.1 Hz, 3H).

Workup

  1. stirringThe mixture was stirred for about 10 min
  2. customThe layers were separated
  3. extractionthe aqueous layer was extracted with Et2O (3×30 mL)
  4. washThe combined organic layers were washed with saturated aqueous NaHCO3
  5. dry with materialdried over anhydrous MgSO4
  6. filtrationfiltered
  7. concentrationconcentrated to dryness under reduced pressure
  8. customThe residue was purified via silica gel chromatography
  9. washeluting with 20-60% EtOAc/pentane

Sources & evidence

ORD record
ord-840c6c5b8f104f399806e1a8ba9beb63
Source dataset
uspto-grants-2015_02
Patent number
US08962629B2

Reaction notes

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