1.09 g (4.91 mmol) of 2-(1-hydroxyethyl)-5-phenylpentanoic acid are treated with 660 mg (4.61 mmol) of 1-hydroxy-1H-benzotriazole and 990 mg (9.82 mmol) of 4-methylmorpholine and the mixture is cooled to −20° C. After addition of 940 mg (4.61 mmol) of N′-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride, the mixture is stirred for 30 min. At the same time, the cooling bath is removed. Then, after again cooling to −20° C., 1.00 g (4.09 mmol) of 6-(1-aminoethyl)-3-(4-methoxybenzyl)-1,2,4-triazin-5(4H)-one is added and the mixture is stirred overnight while warming to room temperature. For work-up, the dichloromethane phase is washed with 1N potassium hydrogensulphate solution and then with saturated sodium hydrogencarbonate solution. The dried organic phase is concentrated and chromatographed using the eluent dichloromethane/methanol 100/1 to 30/1.
