A solution of 4-{2-[(3-methylbenzofuran-2-carbonyl)amino]ethoxy}benzoic acid methyl ester (0.340 mol) in chlorobenzene (1000 ml) was treated with 2,2′-azobisisobutyronitrile (5.60 g, 0.017 mol) and N-bromosuccinimide (75.76 g, 0.426 mol). The resulting mixture is heated to 80° C. and stirred for one hour. After completion of reaction, the reaction mixture was cooled to ambient temperature and washed with water, 3% sodium hydrogensulfite, and again with water. Solvent was distilled under reduced pressure and after cooling to ambient temperature, dichloromethane was added and to give 4-{2-[(3-bromomethylbenzofuran-2-carbonyl)amino]ethoxy}benzoic acid methyl ester which was used in the next step.
