To a solution of 4-[3-(6-bromo-hexyl)-2-(2-ethoxycarbonyl-ethyl)-phenoxy]-butyric acid ethyl ester (4.48 g, 9.5 mmol) and 5-bromo-benzene-1,3-diol (1.79 g, 9.47 mmol) in dimethylsulfoxide (30 mL) was added lithium hydride (160 mg, 20 mmol) at room temperature. The resulting suspension was stirred for 48 h and then the reaction mixture was diluted with water (100 mL). The organic compound was extracted into ethyl acetate (3×50 mL) and the combined organic extracts were washed with water (100 mL) and brine solution (100 mL). The organic layers were dried over anhydrous magnesium sulfate and filtration of the drying agent and concentration of the solvent under vacuum gave the crude product which was purified by using an ISCO 120 g column, eluting with 0-30% ethyl acetate in hexanes to afford 4-[3-[6-(3-bromo-5-hydroxy-phenoxy)-hexyl]-2-(2-ethoxycarbonyl-ethyl)-phenoxy]-butyric acid ethyl ester (2.73 g, 74%) as a white solid: ES(+)-HRMS m/e calcd for C29H39BrO7 (M+Na)+ 601.1771, found 601.1773.
