Triethyl 2-fluoro-2-phosphonoacetate (5.72 mL, 28.1 mmol, was added to a stirring solution of lithium diisopropylamide (28.1 mmol) in THF (54 mL) at −78° C. under argon. The dry ice bath was removed for about ten minutes, and then the solution was cooled again to −78° C. A solution of 1-(3-n-propoxy5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)propan-1-one (Intermediate 7, 2.70 g, 9.36 mmol) and THF. (10 mL) was added, and the solution was stirred at 0° C. for 2 h. The reaction was quenched at −78° C. by adding saturated ammonium chloride. The solution was warmed to room temperature and the products were extracted three times with ether. The combined organic layers were washed with water, brine and dried over magnesium sulfate. The solvent was removed in vacuo to give the title compound.
