1-Hydroxybenzotriazole (864 mg, 6.4 mmol), tryptamine (512 mg, 3.2 mmol) and N-methylmorpholine (0.703 ml, 6.4 mmol) were added to a solution of (4-dimethylamino-4-(4-fluorophenyl)cyclohexylidene)acetic acid hydrochloride (840 mg, 3.2 mmol) in abs. dimethylformamide (25 ml) under argon. The solution was cooled to 0° C., dicyclohexylcarbodiimide (1.32 g, 6.4 mmol) was added and the mixture was stirred at RT for 4 d. Working up of the mixture was carried out by separating off the urea which had precipitated out and introducing the filtrate 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 filtrate was diluted with water (400 ml), 5 M sodium hydroxide solution (5 ml, 25 mmol) was added and the mixture was stored at 5° C. for 4 d. The product thereby precipitated out as a beige-coloured oily solid in a yield of 95% (1.27 mg).
