17.85 g (50 mmol) of 1.5-bis(2,6-dioxomorpholino)-3-carboxymethyl-3-azapentane is stirred in 200 ml of dimethylformamide and mixed with 9 ml (50 mmol) of water. The solution is heated for 3 hours to 70° C., cooled off to 0° C. and 36.07 ml (260 mmol) of triethylamine and 10.8 g (50 mmol) of 11-aminoundecanoic acid ethyl ester are added. After stirring overnight at room temperature, the solution is evaporated to dryness in a vacuum. The residue is taken up in 100 ml of water and the solution is mixed by drops with concentrated hydrochloric acid until permanent cloudiness. After stirring overnight in the ice bath, the finely crystalline precipitate is suctioned off, washed with water and dried in a vacuum at 50° C. 14.9 g (65% of theory) of the title compound is obtained as a white powder with melting point 155-157° C.
