Reaction #40324

Reaction equation

hydrochloric acid

Dibromopentane

cyclohexanone

potassium tert-butanolate

→

Spiro[5.5]undecan-1-one

Solvents

toluene

Conditions

Workup

1. 1
   Temperaturethe reaction mixture is refluxed for 48 hours
2. 2
   workup.ADDITIONis added
3. 3
   Extractionextraction
4. 4
   OtherThe combined organic phases produce
5. 5
   Dryingafter drying over sodium sulphate, removal of the solvent in a vacuum and chromatography of the residue

Procedure

Dibromopentane (5 mmol) is added to a solution of cyclohexanone (5 mmol) and potassium-tert-butanolate (10 mmol) in toluene (7.5 ml) and the reaction mixture is refluxed for 48 hours. After cooling to room temperature 25% hydrochloric acid is added and extraction is carried out with diethyl ether. The combined organic phases produce, after drying over sodium sulphate, removal of the solvent in a vacuum and chromatography of the residue using silica gel (ethyl acetate/heptane, 1:5) pure spiro[5.5]undecan-1-one (Tetrahedron 1964, 20, 2553-2573): tR 1.90 min. (LC-2); ESI-MS (+): m/z 167.27 [M+H]+.

Source