Acetaldehyde → HCID 67528490, compound

Participants

Reaction Conditions

Reaction Steps

At −78° C., a solution of n-butyl lithium (37.3 ml, 1.6M in hexane, 59 mmol) was treated with a solution of diisopropylamine (5.8 g, 57 mmol) in tetrahydrofuran (35 ml). The resulting solution was warmed to −20° C., cooled to −78° C., and treated with a solution of the crude 1-(6-ethyl-2-methylcyclohex-3-enyl)ethan-1-one mixture (8.1 g) in tetrahydrofuran (40 ml). The resulting solution was stirred 1 h at −70° C., warmed to 0° C., cooled at −70° C. and treated with a solution of acetaldehyde (10.5 g, 239 mmol) in tetrahydrofuran (40 ml). After 1 h stirring, a mixture of aqueous 2N HCl (50 ml) and saturated aqueous NaCl solution (50 ml) was added and the reaction mixture warmed to 0° C. The aq. phase was extracted with diethyl ether (2×100 ml) and the combined org. phases washed with saturated aqueous NaHCO3 solution and water, dried (MgSO4), and concentrated. The residue (13.4 g) dissolved in toluene (50 ml) was treated with para-toluene sulfonic acid monohydrate (0.5 g, 2.6 mmol) and refluxed during 1 h. The reaction mixture was cooled, treated with a saturated aqueous solution of Na2CO3 and the aqueous phase was extracted with cyclohexane (90 ml). The combined organic phases were washed with saturated aqueous NaCl solution, dried (MgSO4) and concentrated. FC (SiO2, hexane/methyl tert.-butyl ether 20:1) of the crude product gave (2E)-1-(rel-(1S,2S,6S)-6-ethyl-2-methylcyclohex-3-enyl)but-2-en-1-one (0.7 g, 3 steps: 7%) and a 67:27:6 mixture of (2E)-1-(rel-(1S,2S,6S)-/(2E)-1-(rel-(1R,2S,6S)-6-ethyl-2-methylcyclohex-3-enyl)but-2-en-1-one/unassigned stereoisomer (5.7 g, 3 steps: 58%).

Provenance & Evidence