Ethyl 5-oxo-6-methyl-6-heptenoate (CAS NO.: ) could be produced through the following synthetic routes.

A 300-mL, four-necked, round-bottomed flask containing a magnetic stirring bar is fitted with a serum cap, a thermometer, a 100-mL serum-capped pressure-equalizing addition funnel, and a reflux condenser equipped at the top with a nitrogen inlet. The dry apparatus is flushed with nitrogen and 5.6 g (85.5 mmol) of zinc–copper couple and 20 mL of benzene are introduced. A mixture of 13.8 g (57 mmol) of ethyl 4-iodobutyrate, 9 mL of N,N-dimethylacetamide, and 70 mL of benzene is transferred into the addition funnel by cannulation techniques and added to the stirred Zn(Cu) suspension over 3 min at room temperature. The mixture is vigorously stirred for 1 hr at room temperature and then heated at gentle reflux with an oil bath for 4.5 hr. After the mixture is cooled to 60°C, a solution of 0.58 g (0.5 mmol) of tetrakis(triphenylphosphine)palladium(0) in 15 mL of benzene is added over 1 min through the addition funnel and stirring is continued for 5 min at the same temperature. The oil bath is removed, a solution of 5.23 g (50 mmol) of methacryloyl chloride in 10 mL of benzene is added through the addition funnel over a period of 5 min, and stirring is continued for 1 hr. The mixture is filtered with suction through a Celite pad on a medium-fritted funnel and the filter cake is washed with 200 mL of diethyl ether. The filtrate is washed successively with 50 mL of 1 N ammonium chloride, 10 mL of saturated sodium hydrogen carbonate and 50 mL of saturated sodium chloride. The aqueous phases are extracted with 100 mL of diethyl ether. The combined organic extracts are dried over magnesium sulfate and the solvents are removed with a rotary evaporator to yield a deep-brown mobile oil. This is purified by chromatography on 200 g of silica gel with a hexane–diethyl ether gradient (10 : 1, 400 mL; 5 : 1, 400 mL, and 2 : 1, 600 mL), followed by distillation in the presence of hydroquinone (10 mg) in a Kugelrohr apparatus to give 8.0–8.1 g (87–88%) of the product as a colorless liquid, bp 185°C (20 mm).