1.0M Toluene-solution of lithium bis(trimethylsilyl)amide (1.89 ml) was added to bis(dibenzylideneacetone)palladium (0) (39 mg) and tri-tert-butylphosphine tetrafluoroborate (20 mg) at 70° C. under an atmosphere of nitrogen, a solution of 8-(5-bromopyridin-2-yl)-1,4-dioxaspiro[4,5]decane-8-carboxylic acid ethyl ester (500 mg) in toluene (1.4 ml) was added dropwise and stirred at the same temperature for 0.5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, tetrabutylammonium fluoride (4.7 ml) was added and stirred at the same temperature for an hour. Then, a saturated aqueous solution of sodium bicarbonate was added and extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate and concentrated. The resulting residue was purified with silica gel column chromatography (n-hexane/ethyl acetate) to give the titled compound (312 mg) as a yellow oil.
