Methyl 9-oxo-13-phenyl-tridecanoate (1.8 g, 5.65 mmol) was dissolved in toluene (5.0 mL), and ethylene glycol (0.935 mL, 16.8 mmol), methyl orthoformate (1.85 mL, 16.8 mmol), and p-toluenesulfonic acid monohydrate (53.0 mg, 0.279 mmol) were then added in order at room temperature. The mixture was stirred for 40 minutes, and then quenched with a saturated aqueous solution (30 mL) of sodium bicarbonate, and 10% methanol/ethyl acetate (100 mL) was then added. The mixture was separated. The organic layer was washed with a mixture of water (10 mL) and a saturated aqueous solution (30 mL) of sodium chloride, dried over anhydrous sodium sulfate, and filtered. The solvent was then distilled off under reduced pressure. The residue was purified on Biotage (silica gel, n-hexane/ethyl acetate) to obtain 1.88 g (5.19 mmol, yield 92%) of methyl 8-[2-(4-phenyl-butyl)-[1,3]dioxolan-2-yl]-octanoate.
