Triethylamine (0.030 mL, 0.218 mmol) was added to a solution of (3R,6S)-3-amino-6-(2,3-difluorophenyl)-1-(2-methoxyethyl)azepan-2-one (65 mg, 0.218 mmol) and 4-nitrophenyl chloroformate (44 mg, 0.218 mmol) in tetrahydrofuran (3 mL) at 0° C. After 30 min, 2-oxo-1-(4-piperidinyl)-2,3-dihydro-1H-imidazo[4,5-b]pyridine dihydrochloride (70 mg, 0.240 mmol), triethylamine (0.120 mL, 0.872 mmol), and dichloromethane (5 mL) were added and the mixture allowed to warm to ambient temperature. After 4.5 h, the mixture was concentrated. Purification by silica gel chromatography [100% dichloromethane→95% dichloromethane/methanol (10% ammonium hydroxide/methanol)] gave the title compound (88 mg). The title compound was converted to the HCl salt with 2M HCl in ether. MS 543.3 (M+1). 1H NMR (500 MHz, CD3OD) δ 8.09 (dd, J=7.8 Hz, 1.0 Hz, 1H), 7.99 (dd, J=6.1 Hz, 1.0 Hz, 1H), 7.36 (m, 1H), 7.17-7.10 (m, 3H), 4.78 (d, J=11.0 Hz, 1H), 4.61-4.54 (m, 1H), 4.31-4.24 (m, 2H), 4.18-4.13 (m, 1H), 3.94-3.89 (m, 1H), 3.57-3.53 (m, 2H), 3.48-3.43 (m, 1H), 3.39 (d, J=15.1 Hz, 1H), 3.34 (s, 3H), 3.19-3.15 (m, 1H), 3.07-2.96 (m, 2H), 2.49-2.41 (m, 1H), 2.35-2.26 (m, 1H), 2.19-2.06 (m, 3H), 1.90-1.76 (m, 3H).
