3-[4-cyanobenzyl]aminobenzoic acid (0.25 g; 1 mmol), β-alanine ethyl ester.HCl (0.15 g; 1 mmol), N,N-diisopropylethylamine (0.26 g; 2 mmoles) and benzotriazol-1-yl-oxy-tris(dimethylamino)phosphonium hexafluorophosphate (0.44 g; 1 mmol) were stirred in N,N-dimethylformamide (25 ml) at room temperature for 1 hr. The reaction mixture was taken down to dryness and the residue was redissolved in ethanol (30 ml). The solution was saturated with HCl gas and allowed to stir overnight. The mixture was taken down to dryness and the residue was redissolved in ethanol (20 ml). To this solution, ammonium chloride (1 g) and ammonium hydroxide (10 ml) were added. The reaction mixture was stirred at room temperature overnight and the solvent was removed under reduced pressure. The residue was purified by HPLC using acetonitrile/water/trifluoroacetic acid system. The desired fractions were collected and lyophilized to give 190 mg of white material. FAB-MS: MH+ =369.5
