Methyl (1α,4aβ,8aα)-2-oxodecahydro-1-naphthoate (CAS NO.: ) could be produced through many synthetic methods.

(350 mL) is dried over sodium amide for 20 min, then distilled under a positive pressure of dry nitrogen into a flame-dried, 1-L, three-necked, round-bottomed flask equipped with a dry ice condenser, rubber septum and magnetic stirring bar. The flask is cooled to -78°C and small pieces of lithium (1.11 g, 0.16 mol) are added over 10 min to afford a deep blue solution. A solution of enone 1 (10.08 g, 0.07 mol) in tert-butyl alcohol (5.10 g, 0.07 mol) and ether (40 mL) is added dropwise over a 15-min period at -78°C, and then sufficient isoprene is added dropwise to discharge the residual blue color of the reaction mixture. The ammonia is allowed to evaporate under a stream of dry nitrogen and the ether is removed under reduced pressure to leave a white foam. After a further 5 min under high vacuum, the nitrogen atmosphere is restored, the lithium enolate 2 is suspended in dry ether (80 mL) at -78°C by vigorous stirring, and methyl cyanoformate (6.73 g, 0.08 mol) is added over a 5-min period. Stirring is maintained at this temperature for a further 40 min and then the mixture is allowed to warm to 0°C. (500 mL) and ether (200 mL) are added and the mixture is stirred vigorously until the precipitate has dissolved. After separation of the organic layer, the aqueous phase is extracted with ether (2 × 300 mL), the combined extracts are washed with water (200 mL) and brine (200 mL), and then dried over anhydrous magnesium sulfate. Removal of solvent under reduced pressure furnishes a pale yellow oil which is dissolved in hexane (200 mL); the solution is kept in the freezer (-28°C) for approximately 1.5 hr, after which time very pale yellow crystals of the β-keto ester 3 are deposited. These are collected by filtration at low temperature and after concentration of the mother liquors, two further crops are collected. Flash chromatography (ethyl acetate/hexane, 13:87) on silica gel (140 g) of the residue (3.5 g) from the remaining mother liquor followed by two recrystallizations affords further 3. The total quantity of 3 obtained is 11.5–11.8 g (81–84% yield).

Notice: salts are formed in this procedure. All procedures should be conducted in a well-ventilated hood and rubber gloves should be worn.