A solution of 3,5-diamino-6-chloropyrazine-2-carboxylic-acid (Intermediate 1.1.1, 46 mg, 0.25 mmol), 3-amino-1-ethoxycarbonylmethyl-1-[3-(4-methoxy-phenyl)-propyl]-piperidinium bromide trifluoroacetate salt (Intermediate 3.1.2, 230 mg, 0.25 mmol), O-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate (86 mg, 0.27 mmol) and N,N-diisopropylethylamine (0.15 mL, 0.1 mmol) in dry N,N-dimethylformamide (5 mL) is stirred for 5 hours at room temperature. The solution is concentrated under reduced pressure to half of the volume, water (2 mL) added and the mixture purified via preparative reverse phase HPLC (gradient of acetonitrile in water+0.05% trifluoroacetic acid). Fractions containing the title compound are concentrated under reduced pressure. The residue is treated with HCl in diethyl ether (2 M, 2 mL), the solvent removed and the residue dried at 50° C. under vacuum. Yield: 56 mg. IC50=0.15.
