A solution of 1-(4-cyano-benzyl)-6-methyl-4-oxo-5-(3-trifluoromethyl-phenyl)-1,4-dihydro-pyridine-3-carboxylic acid (preparation 1, 70 mg, 0.102 mmol), TBTU (37 mg, 0.115 mmol), DIPEA (40 μL, 0.234 mmol) in DMF (0.5 mL) is stirred for 15 min at room temperature. Ethanolamine (7 μL, 0.116 mmol) is added and the reaction mixture is stirred for 1.5 h at room temperature. The reaction mixture is purified by preparative reversed-phase HPLC (Sunfire, gradient of methanol in water, 0.1% TFA, 60° C.). Yield: 16 mg (34% of theory); ESI mass spectrum: [M+H]+=456; Retention time HPLC: 1.34 min (Z002—005).
