To 4-[4-(4-tert-butyl-phenyl)-piperazin-1-yl]-butyric acid ethyl ester (1.41 g; 4.24 mmol, prepared in accordance with Example 166) is added a solution of lithium hydroxide (59 mg; 2.46 mmol in 3 mL of water) diluted with tetrahydrofuran (3 mL) and the resulting mixture is stirred at room temperature for one hour. Acetonitrile (50 mL) is added and the precipitate formed is then filtered and dried under high vacuum to afford the desired product (1.45 g) which is used in the next step without further purification.
