1,4-Cyclohexanedione → 4-Benzylidenecyclohexanone

Participants

Reaction Steps

To a mechanically stirred suspension of 15.24 g (0.035 mole) of benzyltriphenylphosphonium bromide in 150 ml of THF there was added first 22 ml of 1.61 N n-butyllithium in pentane and then 5.0 g (0.032 mole) of cyclohexane-1,4-dione, ethylene monoketal in 50 ml of THF. Following 5 hours' heating at reflux the mixture was allowed to cool and was then washed in turn with water and brine. The organic layer was concentrated, and the residue was chromatographed on 1 liter of silica gel, eluting with 20% ethyl acetate in Skellysolve® B, to afford 7.15 g (97%) of 4-benzylidenecyclohexanone, ethylene ketal as an oil, the nmr spectrum of which is in consonance with the structure.

Provenance & Evidence