Dichloromethane → 1-(2,2,4-Trimethyl-3-cyclohexen-1-yl)ethan-1-one

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

In a 500 ml sulfonation flask with cooling funnel, dropping funnel and mechanical stirring under air (*) at 5° C. was added but-3-en-2-one (43 ml; 0.52 mol) then THF (4.2 ml; 52 mmol) followed by a careful portionwise addition of aluminum chloride (3.5 g; 26 mmol). White fumes and increase of temperature to 20° C. were observed. The mixture turned red. The temperature was decreased to 15° C. and 2,4-dimethyl-1,3-pentadiene (68 ml; 0.52 mol) was added dropwise (90 min). Exothermic reaction was observed. The reaction mixture was stirred for 8 hours at 25° C. and for 10 hours at 45° C. As the diene was still detected but-3-en-2-one was added dropwise (22 ml; 0.26 mol) (10 min) and the mixture was stirred for additional 48 hours at 25° C. Dichloromethane (200 ml) was added to the mixture which was stirred for 5 min and filtered over celite. The red solution obtained was poured into cold water (1 l) and extracted with dichloromethane (4×300 ml). Combined organic layers were washed with brine (500 ml) and water (500 ml), dried over sodium sulfate and filtered over silica. The solvent was removed in vacuo to afford 84 g (97% of theory) of 1-(2,2,4-trimethyl-cyclohex-3-enyl)-ethanone as a clear red oil.

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