To a solution of 4′-{[2-ethyl-1-(4-{[1-(hydroxymethyl)cyclobutyl]oxy}phenyl)-6-oxo-4-propyl-1,6-dihydropyrimidin-5-yl]methyl}biphenyl-2-carbonitrile (0.5 g) and 2,6-lutidine (0.17 mL) in dichloromethane (5 mL) was added tert-butyl(dimethyl)silyl trifluoromethanesulfonate (0.34 mL) at 0° C., and the mixture was stirred overnight. The reaction mixture was diluted with ethyl acetate, washed with 5% aqueous potassium hydrogen sulfate solution and then with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure. A mixture of the residue, hydroxylammonium chloride (0.67 g), sodium hydrogen carbonate (0.97 g) and dimethyl sulfoxide (5 mL) was stirred overnight at 90° C. 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 (5 mL). N,N′-carbonyldiimidazole (0.23 g) and then 1,8-diazabicyclo[5.4.0]undec-7-ene (0.23 mL) were added, and the mixture was stirred at room temperature for 30 min. Tetrabutylammonium fluoride (1.0 M tetrahydrofuran solution, 1.9 mL) was added, and the mixture was stirred overnight at 50° C. The reaction mixture was diluted with ethyl acetate, washed with 5% aqueous potassium hydrogen sulfate solution 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 (0.43 g, 76%) as an amorphous solid.
