5-Methyl-5-hexen-2-one (CAS no.: ), which is known as 5-Methylene-2-hexanone, could be produced through the following synthetic routes.

In a 1-l. round-bottomed flask equipped with a condenser are placed 78.0 g. (0.56 mole) of commercial anhydrous potassium carbonate, 45.0 g. (0.50 mole) of methallyl chloride, 55.0 g. (0.55 mole) of 2,4-pentanedione, and 300 ml. of anhydrous ethanol. The mixture is refluxed on a steam bath for 16 hours. The condenser is replaced by a distilling head and condenser, and about 200 ml. of ethanol is distilled from the mixture. Ice water (600 ml.) is added to dissolve the salts, and the mixture is extracted three times with ether. The combined ether extracts are washed twice with 100 ml. of saturated sodium chloride solution, dried for 30 minutes over anhydrous magnesium sulfate, and filtered; the solvent is evaporated. The residue is distilled through a 6-in. Vigreux column using an oil bath maintained at 190° to give 26–29 g. (47–52%) of the product, b.p. 145–155°.