A mixture of (S)-2-carboxy-3-(3-chloro-4-methoxybenzylamino)-5-(2-hydroxymethyl-1-pyrrolidinyl)pyrazine (80 mg) obtained in Example 22 (5), 2-aminomethyl-4-methylmorpholine (31.9 mg), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (43 mg), 1-hydroxybenzotriazole (30.3 mg) in N,N-dimethylformamide (3 ml) is stirred at room temperature for 18 hours. To the reaction mixture is poured water, and the mixture is extracted with ethyl acetate. The extract is washed with water, a saturated aqueous sodium hydrogen carbonate solution and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue is purified by silica gel flash column chromatography (solvent; ethyl acetate) to give (S)-2-[N-(4-methyl-2-morpholinyl)methylcarbamoyl]-3-(3-chloro-4-methoxybenzylamino)-5-(2-hydroxymethyl-1-pyrrolidinyl)pyrazine (80.5 mg), MS (m/z): 505 (MH+), IR (Nujol): 3295, 1635 cm−1.
