Triethylamine (0.006 mL, 0.035 mmol) was added to a solution of (3R,6S)-3-amino-1-(cyclopropylmethyl)-6-phenylazepan-2-one (9 mg, 0.035 mmol) and p-nitrophenyl chloroformate (7 mg, 0.035 mmol) in tetrahydrofuran (0.500 mL) at 0° C. After 0.5 h, diisopropylethylamine (0.027 mL, 0.14 mmol), 5-phenyl-1-piperidin-4-yl-2,4-dihydro-3H-1,2,4-triazol-3-one hydrochloride (9 mg, 0.035 mmol), and dichloromethane (0.500 mL) were added and the mixture was heated to reflux. After 2 h, the mixture was concentrated. Purification by reverse phase HPLC (C-18, 95% water/acetonitrile→5% water/acetonitrile with 0.1% trifluoroacetic acid) gave the title compound. MS 529.3 (M+1).
