A mixture of (3-amino-propyl)-{2-[(3,5-diamino-6-chloro-pyrazine-2-carbonyl)-amino]-ethyl}-dimethyl-ammonium bromide (Intermediate M) (1.0 g, 2.52 mmol), 4-benzyloxyphenylacetic acid (0.61 g, 2.52 mmol), N-methylmorpholine (1.0 mL, 9.10 mmol), N,N′-dicyclohexylcarbodiimide (0.52 g, 2.52 mmol) and 1-hydroxybenzotriazole (0.34 g, 2.52 mmol) in anhydrous DMF (20 mL) is stirred under a nitrogen atmosphere at RT for 16 h. The reaction mixture is concentrated under vacuum and is purified by column chromatography (basic alumina, 0-3% MeOH in DCM) to afford the title compound as a white solid. M+ 540. 1H NMR (400 MHz, DMSO-d6) δ 8.23 (1H, t), 8.07 (1H, t), 7.52 (2H, br), 7.41-7.28 (5H, m), 7.16 (2H, d), 7.09 (2H, br), 6.91 (2H, d), 5.05 (2H, s), 3.58-3.3.51 (2H, m), 3.40-3.25 (6H, m), 3.11-3.03 (2H, m), 3.02 (6H, s), 1.87-1.75 (2H, m).
