Process 2: A toluene (50 mL)-acetic acid (7 mL) solution of methyl 2-{[6-(2-cyanophenyl)pyridin-3-yl]methyl}-3-oxoheptanoate (3.50 g, 10.0 mmol) and ammonium acetate (23.2 g, 300 mmol) was refluxed for 1 hour under heating. The solvent was distilled off and the residues were added anhydrous acetic acid (51.2 g) and acetic acid (5.7 g) under room temperature, and the reaction solution was stirred at 0° C. for 30 minutes, and then stirred at 70° C. for 1.5 hours. The reaction solution was added aqueous sodium bicarbonate, and extracted with chloroform. The organic layer was combined, washed with brine, dried over anhydrous sodium sulfate, and concentrated in vacuo. The residues obtained were subjected to silica gel column chromatography (hexane/acetone=5:1), to obtain methyl(Z)-3-acetamido-2-{[6-(2-cyanophenyl)pyridin-3-yl]methyl}-2-heptenoate (0.975 g, 25%) as a pale yellow oil.
