To a solution of 3-[(R)-2-amino-2-(2-hydroxy-phenyl)-ethyl]-1-(2-fluoro-6-trifluoromethyl-benzyl)-6-methyl-5-[4-(5-trifluoromethyl-furan-2-ylmethyl)-piperazin-1-yl]-1H-pyrimidine-2,4-dione (15-1) (67 mg, 0.100 mmol) in 1,2-dicholoroethane (2 mL) were 4-oxo-butyric acid methyl ester (17 mg, 0.150 mmol) and sodium triacetoxyborohydride (42 mg, 0.200 mmol) in the order, followed by stirring at room temperature for 1.5 hrs. The solution was neutralized with an aqueous saturated sodium bicarbonate solution to separate an organic layer. After concentration of the organic layer, the residue was purified using silica gel chromatography(eluent: dichloromethane/methanol, 30/1) and dried in a vacuum to afford 40 mg of the compound as a colorless oil (yield 53%). 1H NMR (300 MHz, CDCl3) δ 1.79 (2H, m), 2.20-2.33 (4H, m), 2.32 (3H, s), 2.48 (2H, m), 2.60 (2H, t), 2.80 (2H, m), 3.58 (2H, m), 3.61 (2H, s), 3.63 (3H, s), 4.06-4.15 (2H, m), 4.42 (1H, dd), 5.42 (2H, dd), 6.30 (1H, d), 6.72-6.78 (3H, m), 7.06-7.15 (2H, m), 7.26 (1H, m), 7.41 (1H, m), 7.55 (1H, d)
