A mixture of hydroxylammonium chloride (4.33 g), sodium hydrogen carbonate (6.16 g) and dimethyl sulfoxide (20 mL) was stirred at 40° C. for 30 min, 4′-{[1-(2,2-dimethyl-2,3-dihydro-1-benzofuran-5-yl)-2-methoxy-6-oxo-4-propyl-1,6-dihydropyrimidin-5-yl]methyl}biphenyl-2-carbonitrile (1.85 g) was added, and the mixture was stirred at 90° C. for 5 hr. The mixture was allowed to cool to room temperature, water was added to the reaction mixture, and the precipitated solid was collected by filtration. The obtained solid was dissolved in ethyl acetate. The solution was washed with saturated brine and dried over anhydrous sodium sulfate, and the solvent was evaporated. The residue was dissolved in tetrahydrofuran (20 mL), N,N′-carbonyldiimidazole (0.48 g) and then 1,8-diazabicyclo[5.4.0]undec-7-ene (0.45 mL) were added, and the mixture was stirred at room temperature for 30 min. The reaction mixture was diluted with ethyl acetate, washed with 1 M hydrochloric acid and then with saturated brine, and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography to give the title compound as colorless crystals (0.74 g, 66%).
