Triethylamine (0.009 mL, 0.091 mmol) was added to a solution of (3R)-3-amino-6-(4-hydroxyphenyl)azepan-2-one (10 mg, 0.045 mmol) and 4-nitrophenyl chloroformate (18 mg, 0.091 mmol) in N,N-dimethylformamide (0.2 mL) and tetrahydrofuran (0.2 mL) at 0° C. After 1 h, 2-oxo-1-(4-piperidinyl)-2,3-dihydro-1H-imidazo[4,5-b]pyridine dihydrochloride (26 mg, 0.091 mmol) and diisopropylethylamine (0.032 mL, 0.182 mmol) were added and the mixture was allowed to warm to ambient temperature. After 18 h, the mixture was purified by reverse phase HPLC (C-18, 95% water/acetonitrile→5% water/acetonitrile with 0.1% trifluoroacetic acid) to give the title compound (7 mg). MS 465.2243 (M+1).
