ethyl 4-oxoheptanoate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:175.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 92.8 g of diethyl 2-butyrylsuccinate and 23.5 g of boric acid were heated to 150° C. in a round flask with distillation head piece, whereby ethanol distilled off. The mixture was subsequently heated to 175° C. and stirred at this temperature for 4 hours (evolution of carbon dioxide). After completion of the reaction, the mixture was cooled to room temperature, taken up in 500 ml of hexane and washed with 150 ml of 5% (wt./vol.) sodium hydrogen carbonate solution and 100 ml of water. The aqueous phases were back-extracted with 50 ml of hexane. The combined organic phases were dried over sodium sulphate and freed from solvent on a rotary evaporator. Distillation of the resulting crude product in a high vacuum over a Vigreux column gave in the main run 58.6 g (89.6%) of ethyl 4-oxoheptanoate as a colourless liquid; b.p. 50°-56° C./0.2 Torr. distilled off After completion of the reaction the mixture was cooled to room temperature washed with 150 ml of 5% (wt./vol.) sodium hydrogen carbonate solution and 100 ml of water The aqueous phases were back-extracted with 50 ml of hexane The combined organic phases were dried over sodium sulphate freed from solvent on a rotary evaporator Distillation of the resulting crude product in a high vacuum over a Vigreux column

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

Procedure: 78 g (0.5 mol) of 1-(3,3-dimethyl-cyclohexyl)-ethanol, 86.9 g (0.55 mol) of 3-oxo-hexanecarboxylic acid ethyl ester and 0.6 g sodium ethylate in 50 g ethanol were placed in a 500-ml stirred vessel and boiled under reflux, distilling-off the ethanol via a still head. Then 100 ml water and 100 ml toluene were added to the reaction solution at room temperature, the aqueous phase was separated, the organic phase was washed with water until neutral and concentrated by evaporation. The raw product (139 g) was fractionated on a 30-cm Vigreux column in vacuum. the aqueous phase was separated the organic phase was washed with water until neutral and concentrated by evaporation

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

Procedure: Under an atmosphere of argon, 1.59 g (69.3 mmol) of sodium were added a little at a time to 50 ml of ethanol. The mixture was then stirred under reflux until a homogeneous solution was obtained. 11.0 g (69.3 mmol) of ethyl hexan-3-onecarboxylate were added to the hot alkoxide solution, and the mixture was stirred for 45 min. 6.51 ml (7.93 g, 52.5 mmol) of 1-iodohexane were then slowly added dropwise to the boiling mixture. The mixture was stirred under reflux for 16 h, cooled to room temperature and filtered, and the solvent was then removed under reduced pressure. The residue was taken up in dichloromethane, filtered again and concentrated. The crude product was purified chromatographically (silica gel, petroleum ether: ethyl acetate 30:1). MS (DCI, NH3): 309 [M+H]+. under reflux until a homogeneous solution was obtained the mixture was stirred for 45 min The mixture was stirred under reflux for 16 h filtered the solvent was then removed under reduced pressure filtered again concentrated The crude product was purified chromatographically (silica gel, petroleum ether: ethyl acetate 30:1)

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

Procedure: The preparation was carried out analogously to Example I from 4.04 g (25.0 mmol) of ethyl hexan-3-onecarboxylate and 2.95 ml (4.10 g, 27.3 mmol) of bromocyclopentane. Purification was carried out chromatographically (silica gel, petroleum ether: ethyl acetate 20:1). MS (EI): 226 [M]+. Purification

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

Procedure: A 1 l. three-necked flask, equipped with a dropping funnel, mechanical stirrer and a distillation head with thermometer and Liebig condenser was charged with 515 ml of xylene (b.p. 138°-140°), stirred and heated to boiling. 65.9 g of a 24% (wt/wt) sodium methoxide solution (prepared as in Example 1) in methyl alcohol (15.8 g = 0.293 moles) was added over 10 min., distilling off continuously the methyl alcohol. 300 ml of additional xylene were added and distillation was continued until the vapor temperature reached 135°. After the addition of 6.6 ml of dimethylsulfoxide, a solution of 40 g (0.232 moles) of 4-oxoheptanoic acid ethyl ester in 80 ml of xylene was added over 25 min. to the vigorously stirred sodium methoxide suspension while keeping the vapor temperature at ca. 135°C by continuous distillation of xylene. The orange-colored mixture was stirred and heated for an additional 5 min. and then allowed to cool to room temperature. Water was added, the mixture was acidified and the product filtered, washed, dried and recrystallized from water to afford 13.45 g (46%) of 2-ethyl-cyclopentan-1,3-dione, m.p. (uncorr.): 171°-172°C. three-necked flask, equipped with a dropping funnel, mechanical stirrer heated to boiling distilling off continuously the methyl alcohol 300 ml of additional xylene were added distillation reached 135° After the addition of 6.6 ml of dimethylsulfoxide at ca. 135°C by continuous distillation of xylene The orange-colored mixture was stirred heated for an additional 5 min. Water was added the product filtered washed dried recrystallized from water