A mixture of hydroxylammonium chloride (0.92 g), sodium hydrogen carbonate (1.31 g) and dimethyl sulfoxide (12 mL) was stirred at 40° C. for 30 min, 4′-{[5-[4-(2-{[tert-butyl(dimethyl)silyl]oxy}-1,1-dimethylethoxy)phenyl]-4-ethyl-6-oxo-2-propylpyrimidin-1(6H)-yl]methyl}biphenyl-2-carbonitrile (0.99 g) was added, and the mixture was stirred at 90° C. for 12 hr. The reaction mixture was diluted with ethyl acetate, washed with water and then with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure. The residue was dissolved in tetrahydrofuran (12 mL). N,N′-carbonyldiimidazole (0.38 g) and then 1,8-diazabicyclo[5.4.0]undec-7-ene (0.35 mL) were added, and the mixture was stirred at room temperature for 2 hr. The reaction mixture was diluted with ethyl acetate, washed with water and then with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure. The residue was dissolved in tetrahydrofuran (10 mL), tetrabutylammonium fluoride tetrahydrofuran solution (1 mol/L, 2.6 mL) was added, and the mixture was stirred at room temperature for 3 hr. The solvent was evaporated from the reaction mixture under reduced pressure. The residue was diluted with ethyl acetate, washed with water and then with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography to give the title compound as a colorless amorphous solid (0.38 g, 75%).
