Potassium tert-butoxide → Ethyl 2-ethyl-4-methylenecyclopentanecarboxylate

HRID 1969698Notes

Reaction equation

HRID 1969698 reaction equation
[CH3:1]C([O-])(C)C.[K+].[CH2:7]([CH:9]1[CH2:13][C:12](=O)[CH2:11][CH:10]1[C:15]([O:17][CH2:18][CH3:19])=[O:16])[CH3:8]>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1COCC1>[CH2:7]([CH:9]1[CH2:13][C:12](=[CH2:1])[CH2:11][CH:10]1[C:15]([O:17][CH2:18][CH3:19])=[O:16])[CH3:8]

Participants

5

Reactant 2

HCID 23665647Potassium tert-butoxideHCID 58010012Cyclopentanecarboxylic acid, 2-ethyl-4-oxo-, ethyl ester

Product 1

HCID 58558026Ethyl 2-ethyl-4-methylenecyclopentanecarboxylateYield 64.5%

Reagents, catalysts & solvents 2

HCID 74505Methyltriphenyliphosphonium bromideCatalystHCID 8028TetrahydrofuranSolvent2×

Procedure

A solution of KOt-Bu (3.65 g, 32.6 mmol) and methyltriphenylphosphonium bromide (11.6 g, 32.6 mmol) in THF (69.5 mL) was cooled to about −10° C. A solution of ethyl 2-ethyl-4-oxocyclopentanecarboxylate (4.00 g, 21.7 mmol) in THF (17.4 mL) was added dropwise while the temperature was kept at about 0° C. The reaction mixture was allowed to warm to ambient temperature and stirred for about 16 h. The insoluble material was removed by filtration. The filtrate was concd under reduced pressure. The resulting material was purified by silica gel (120 g) chromatography eluting with a gradient of 0-20% EtOAc in heptane to provide ethyl 2-ethyl-4-methylenecyclopentanecarboxylate (2.55 g, 64%) as a colorless liquid: 1H NMR (d-DMSO) δ 4.88-4.78 (m, 2H), 4.16-3.96 (m, 2H), 2.66-2.31 (m, 4H), 2.24-1.82 (m, 2H), 1.50 (m, 1H), 1.35-1.22 (m, 1H), 1.18 (t, 3H), 0.85 (m, 3H).

Workup

  1. customwas kept at about 0° C
  2. customThe insoluble material was removed by filtration
  3. customThe resulting material was purified by silica gel (120 g) chromatography
  4. washeluting with a gradient of 0-20% EtOAc in heptane

Sources & evidence

ORD record
ord-faf60a2daeae448c845bf54f14f3f1b3
Source dataset
uspto-grants-2013_04
Patent number
US08426411B2

Reaction notes

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