3-phenylpropylamine (768 mg, 5.68 mmol), N-methylmorpholine (1.15 g, 11.36 mmol) and dicyclohexylcarbodiimide (2.34 g, 11.36 mmol) were added to a solution of [4-dimethylamino-4-(3-fluoro-phenyl)-cyclohexylidene]acetic acid (1.5 g, 5.68 mmol) in dry dimethylformamide (35 ml) under argon and the mixture was stirred at RT for 3 d. The urea which had precipitated out was separated off and the filtrate was introduced into a mixture of saturated NaCl solution (40 ml) and saturated NaHCO3 solution (10 ml). Still further urea thereby precipitated out and was separated off. The aqueous phase was diluted with water (300 ml), 5 M sodium hydroxide solution (7 ml, 35 mmol) was added and the mixture was stored at 5° C. for 20 h. The crude product thereby precipitated out as a beige-coloured solid (2.16 g). After chromatography on silica gel G [100 g; EtOAc/MeOH (10:1)], the amide was obtained in a yield of 29% (648.5 mg) with an m.p. of 129-131° C.
