The synthetic process of 2-Acetyl-2-cyclohexen-1-one (CAS NO. ) contains 2 steps. The synthetic route is as follows:

A. Produce 2-Acetyl-2-phenylselenocyclohexanone: a 500 ml, three-necked, round-bottomed flask is fitted with a mechanical stirrer, a pressure-equalizing dropping funnel, and a combined inlet-outlet assembly connected to a nitrogen source and a bubbler. The flask is charged with 3.36 g (0.140 mole) of sodium hydride, the apparatus is flushed with nitrogen, and 100 ml of tetrahydrofuran is added. The suspension is stirred and cooled in an ice bath under a static nitrogen atmosphere as a solution of 14.02 g (0.100 mole) of 2-acetylcyclohexanone in 15 ml of tetrahydrofuran is added over a 15 minute period. The formation of the sodium enolate is complete when hydrogen evolution ceases and a thick suspension has developed. Stirring and cooling are continued for 20 minutes, after which a solution of 20.1 g (0.105 mole) of benzeneselenenyl chloride in 20 ml of tetrahydrofuran is rapidly added. The contents of the flask are stirred at 0 °C for 15 minutes and poured into a beaker containing a magnetically stirred mixture of 200 ml of 1:1 (v/v) diethyl ether-pentane, 50 ml of aqueous 7% sodium hydrogen carbonate, and 50 g of ice. The layers are separated, and the aqueous layer is extracted with 50 ml of 1:1 (v/v) ether–pentane. The combined organic extracts are washed with 50 ml of saturated aqueous sodium chloride and dried by filtration through a cone of anhydrous sodium sulfate. Evaporation of the solvents under reduced pressure gives 29.2–30 g of crude, solid 2-acetyl-2-phenylselenocyclohexanone which is used in Part B without purification.

B. Produce 2-Acetyl-2-cyclohexen-1-one: a 500 ml, three-necked, round-bottomed flask equipped with a pressure-equalizing dropping funnel, a reflux condenser, a thermometer, and a magnetic stirring bar is charged with a solution of 29.2–30 g (ca. 0.1 mole) of crude 2-acetyl-2-phenylselenocyclohexanone in 100 ml of dichloromethane. The solution is stirred at room temperature, and a 2–3 ml portion from a solution of 23.8 g of 30% hydrogen peroxide (7.14 g, 0.21 mole) in 20 ml of water is added to initiate the oxidation. After the exothermic reaction begins, the mixture is stirred and cooled in an ice–salt bath as necessary to keep the temperature between 30 and 35 °C while the remainder of the hydrogen peroxide solution is added. When the oxidation is complete, the ice–salt bath is removed, and vigorous stirring is continued for 15 minutes at room temperature and 15 minutes at 0 °C. The chilled suspension of benzeneseleninic acid is filtered, and the filter cake is washed with 50 ml of dichloromethane. The dichloromethane layer from the filtrate is washed with 50 ml of aqueous 7% sodium hydrogen carbonate, dried by filtration through a cone of anhydrous sodium sulfate, and evaporated, providing 12.8–13.7 g of crude product. Distillation in carefully washed glassware at 0.1 mm. using a Kügelrohr apparatus with an oven temperature of 50–55 °C gives 11.0–11.9 g (79–85%) of 2-acetyl-2-cyclohexen-1-one.