3-oxobutan-2-yl benzoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 3-benzoyloxybutan-2-one (15.5 g) and dimethylformamide dimethylacetal (14.4 g) was heated on a steam bath for 2 hours 30 minutes. The solvent was removed from the mixture under reduced pressure. Petroleum ether (b.p. 60°-80° C.) was added to the residue, with shaking and the ether layer separated from an insoluble red oil. Further petroleum ether was added to the oil with shaking and excess ether was removed under reduced pressure to give a red-brown oil which partially crystallised on standing overnight. Petroleum ether was added and the solid was collected by filtration and washed with petroleum ether to give a yellow crystalline solid of 4-benzoyloxy-1-dimethylamino-1-penten-3-one. Yield 5.6 g. The solid was used directly without further purification in the next step. was heated on a steam bath for 2 hours 30 minutes The solvent was removed from the mixture under reduced pressure Petroleum ether (b.p. 60°-80° C.) was added to the residue the ether layer separated from an insoluble red oil Further petroleum ether was added to the oil with shaking excess ether was removed under reduced pressure to give a red-brown oil which partially crystallised Petroleum ether was added the solid was collected by filtration washed with petroleum ether

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 3-chlorobutanone (10.6 g), benzoic acid (15.0 g), triethylamine (30 ml) and acetonitrile (100 ml) was heated under reflux for 1 hour 30 minutes. The mixture was cooled and filtered to remove precipitated triethylamine hydrochloride. The acetonitrile was removed from the filtrate under reduced pressure and the residue dissolved in ethyl acetate and washed with water. The organic extracts were dried over magnesium sulphate, filtered over active carbon and the solvent was removed from the filtrate under reduced pressure, to give a yellow oil of 3-benzoyloxybutan-2-one. Yield 16.7 g. The oil was used directly without further purification in the next step. was heated under reflux for 1 hour 30 minutes The mixture was cooled filtered to remove precipitated triethylamine hydrochloride The acetonitrile was removed from the filtrate under reduced pressure the residue dissolved in ethyl acetate washed with water The organic extracts were dried over magnesium sulphate filtered over active carbon the solvent was removed from the filtrate under reduced pressure