2,4,6-Trimethylpyridine → 2,2-Dimethyl-3-p-tolyl-cyclobutanone

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Trifluoroacetic anhydride (25 g, 0.09 mol) was added portionwise over a period of 10 minutes at −10° C., to a solution of N,N-dimethyl-isobutyramide (9.16 g) in DCM (100 mL). The resulting mixture was stirred at −10° C. for 10 minutes and then a viscous solution of 4-methylstyrene (8.2 g) and collidine (11.9 mL) in DCM (15 mL) was added portionwise at −10° C. The resulting mixture was heated at reflux for 22 hours then cooled and concentrated under reduced pressure. The oil residue was washed with ethyl ether and the organic phase was decanted away. DCM (75 mL) and water (75 mL) were added to the oil and the mixture was heated at 100° C. for 6 hours. The mixture was cooled to room temperature, separated, and the aqueous layer was extracted with DCM. The combined organic extracts were dried over Na2SO4, filtered, and evaporated under reduced pressure to give 35 g of crude oil, which was purified by flash chromatography (5% to 50% of EtOAc in hexane) to give 6.45 g (50% yield) of 2,2-dimethyl-3-p-tolyl-cyclobutanone as a yellow oil.

Herkunft & Nachweise