6.2 g 2-[4-(2-Aminoethyl)-phenyl]-butyric acid hydrochloride are suspended in 100 ml acetone. After the addition of 50 ml 2 N aqueous sodium hydroxide solution, a solution of 4.8 g 5-chloro-2-methoxybenzoyl chloride in 50 ml acetone is added dropwise thereto at ambient temperature and the reaction mixture then stirred for 2 hours at 50° C. After cooling, the reaction mixture is evaporated in a vacuum and the aqueous solution acidified with dilute hydrochloric acid. The 2-{4-[2-(5-chloro-2-methoxybenzamido)-ethyl]-phenyl}-butyric acid obtained solidifies upon triturating with diisopropyl ether and is recrystallized from diisopropyl ether. The yield is 3.2 g (42.5% of theory); m.p. 120°-122° C.
