DCC (0.444 g; 2.15 mmole) and N-hydroxy-succinimide (0.247 g; 2.15 mmole) were added to a solution of 2-ethoxy-3-[4-(2-{4-methanesulfonyloxyphenyl}ethoxy)phenyl]propanoic acid (described in Example 2) (0.8 g; 1.96 mmole) in acetonitrile (20 ml) at 0° C. After stirring at room temperature overnight a precipitate was filtered off and diisopropylethylamine (1 ml; 5.88 mmole) and cyanamide (0.165 g; 3.92 mmole) were added. After stirring overnight the reaction mixture was poured onto potassium hydrogen sulfate (1M, 20 ml) and the mixture was extracted with ethyl acetate. The organic phase was washed with water, dried (sodium sulfate) and the solvent was evaporated. Chromatography of the crude product on silica gel using ethyl acetate:heptane; acetic acid (10:10:1) as eluant gave 0.755 g (yield 89%) of N-cyano-2-ethoxy-3-[4-(2-{4-methanesulfonyloxy-phenyl}ethoxy)phenyl]propanoic amide.
