Ammonium Chloride → Ethyl 4-methylidenecyclohexane-1-carboxylate

Methyltriphenylphosphonium bromide (34.1 g, 95.5 mmol) was placed in abs. diethyl ether (420 ml) under a nitrogen atmosphere. At 0° C., potassium tert-butylate (13.1 g, 113.1 mmol) was slowly added. After 30 min, again at 0° C., ethyl-4-oxocyclohexanecarboxylate (10.7 g, 62.9 mmol) was slowly added dropwise as a solution in diethyl ether (80 ml). The reaction mixture was stirred overnight at RT. For working up, the reaction mixture was cooled in an ice bath and mixed with sat. aq. NH4Cl solution (250 ml). The phases were separated and the aqueous phase was shaken out several times with EtOAc (3×200 ml). The combined organic phases were dried over magnesium sulphate and the solvent was removed under vacuum. The precipitate thus formed was removed by suction-filtration and dried overnight using a pump. The mother liquor was placed onto a glass frit filled with silica gel and flushed with ether/hexane (400 ml). The filtrate was concentrated and the residue not dried any further. 7.1 g (66% of the theoretical amount) of the desired product 4-methylenecyclohexane carboxylic acid ethyl ester were obtained.

1. temperaturethe reaction mixture was cooled in an ice bath
2. customThe phases were separated
3. stirringthe aqueous phase was shaken out several times with EtOAc (3×200 ml)
4. dry with materialThe combined organic phases were dried over magnesium sulphate
5. customthe solvent was removed under vacuum
6. customThe precipitate thus formed
7. customwas removed by suction-filtration
8. customdried overnight
9. additionfilled with silica gel
10. customflushed with ether/hexane (400 ml)
11. concentrationThe filtrate was concentrated
12. customthe residue not dried any further

ORD record

ord-2e263d5e555744f19b56589d684a9649

Source dataset

uspto-grants-2011_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07981883B2