To a stirred solution of N-tertbutoxycarbonylglycine (94 mg, 0.535 mmol) in N,N-dimethylformamide (2.0 ml) was added [2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluroniumtetrafluoroborate (172 mg, 0.535 mmol), 1-hydroxybenzotriazole hydrate (14 mg, 0.107 mmol) and N,N-diisopropylethylamine (0.31 ml, 1.78 mmol), and the reaction mixture was stirred for 30 minutes at room temperature. After the addition of N-hydroxy-4-[(3R)-3-methyl-4-(1-methyl-6-oxo-1,6-dihydro-[4,4′]bipyrimidinyl-2-yl)-piperazin-1-yl]-benzamidine (145 mg, 0.356 mmol), the reaction mixture was stirred for one hour at room temperature, and then heated to 110° C. When the reaction was complete (checked by thin layer chromatography), excess reagent was decomposed by the addition of water and the aqueous layer was extracted with ethyl acetate. The extract was washed with water and brine, dried over magnesium sulfate, and concentrated in vacuo. The resulting residue was treated with trifluoroacetic acid, and the reaction mixture was stirred for 1 hour. After removal of the solvent, the residue was purified with HPLC to afford 2-{(2R)-4-[4-(5-aminomethyl-[1,2,4]oxadiazol-3-yl)-phenyl]-2-methyl-piperazin-1-yl}-1-methyl-1H-[4,4′]bipyrimidinyl-6-one (44 mg, 0.096 mmol, 27%) as colorless crystals.
