To a mixture of 4-[3-[6-(3-bromo-5-hydroxy-phenoxy)-hexyl]-2-(2-ethoxycarbonyl-ethyl)-phenoxy]-butyric acid ethyl ester (163 mg, 0.28 mmol) and potassium carbonate (117 mg, 0.84 mmol) were added dimethylformamide (4 mL), acetone (8 mL), and iodoethane (219 mg, 1.4 mmol) at room temperature. The resulting suspension was heated to reflux for 2 days. Then, the reaction mixture was cooled to room temperature and diluted with water (20 mL). The organic compound was extracted into ethyl acetate (2×25 mL) and the combined organic extracts were washed with water (50 mL) and brine solution (50 mL). The organic layers were dried over anhydrous magnesium sulfate and filtration of the drying agent and concentration of the solvent gave the crude product which was purified by using an ISCO 40 g column, eluting with 0-30% ethyl acetate in hexanes to afford 4-[3-[6-(3-bromo-5-ethoxy-phenoxy)-hexyl]-2-(2-ethoxycarbonyl-ethyl)-phenoxy]-butyric acid ethyl ester (166 mg, 98%) as a colorless oil: ES(+)-HRMS m/e calcd for C31H43BrO7 (M+H)+ 607.2265. found 607.2270.
