Lithium bis(trimethylsilyl)amide (60 mL, 60 mmol, 1 M in THF) was slowly added to a solution of 2-(4-chloro-2-[1,3]dioxolan-2-yl-phenoxy)-butyric acid methyl ester (15 g, 50 mmol) in anhydrous THF (150 mL) at −78° C. After the mixture was stirred for 15 min, iodoethane (9.3 g, 60 mmol) was added. The mixture was allowed to warm to room temperature and stirred for 2 h. Then the mixture was diluted with ethyl acetate, washed with a saturated aqueous solution of NH4Cl, dried over anhydrous Na2SO4 and concentrated to give the crude product as a oil (16 g).
