Triethylamine (0.452 ml, 3.24 mmol) was added in one portion to 4-((4-oxo-3,4-dihydrophthalazin-1-yl)methyl)picolinic acid (5) (304 mg, 1.08 mmol), 4-(cyclopentyloxy)piperidine hydrochloride (183 mg, 1.08 mmol) and O-benzotriazol-1-yl-N,N,N′,N′-tetra-methyluronium hexafluorophosphate (533 mg, 1.41 mmol) in DMA (3 ml) at 20° C. under air. The resulting mixture was stirred at 20° C. for 3 days. The crude product was purified by preparative HPLC (Waters XBridge Prep C18 OBD column, 5μ silica, 19 mm diameter, 100 mm length), using decreasingly polar mixtures of water (containing 1% NH3) and MeCN as eluents. Fractions containing the desired compound were evaporated to dryness to afford the desired material as a white solid (39 mg, 8.3% yield); 1H NMR (400.132 MHz, DMSO) δ 1.28-1.74 (11H, m), 1.82-1.88 (1H, m), 3.08-3.14 (1H, m), 3.20-3.27 (1H, m), 3.44-3.49 (1H, m), 3.53-3.59 (1H, m), 3.96-4.05 (2H, m), 4.40 (2H, s), 7.39 (1H, d), 7.49 (1H, s), 7.83-7.96 (3H, m), 8.28 (1H, d), 8.47 (1H, d), 12.60 (1H, s); m/z (LC-MS, ESI+), RT=1.88 (M+H 433.1).
