To a solution of (R)-6-allyl-3-((S)-3,3-dimethylbutan-2-yl)-6-(4-fluorophenyl)-1,3-oxazinan-2-one (90 mg, 0.28 mmol) in dry THF (5 mL) was added dropwise 1 M BH3.THF (0.56 mL, 0.564 mmol) at 0° C. After stirring for 2 h at rt, the reaction mixture was cooled to 0° C. and water (1 mL), 3 M aqueous NaOH (0.5 mL) and 30% H2O2 (0.5 mL) were successively added. The mixture was stirred for 2-3 h at rt and was then diluted with water (6 mL). The pH was adjusted to 6-7 with 0.5 N HCl. The aqueous phase was extracted with EtOAc (3×5 mL). The combined organic layers were washed with saturated aqueous NaHCO3 solution (8 mL) and brine (8 mL), dried over Na2SO4, and concentrated in vacuo to give the crude product, which was purified by preparative TLC to afford (R)-3-((S)-3,3-dimethylbutan-2-yl-6-(4-fluorophenyl)-6-(3-hydroxypropyl)-1,3-oxazinan-2-one (2 mg, 2%). LC-MS Method 1 tR=1.179, min, m/z=338.1; 1H NMR (CDCl3) 0.65 (s, 9H), 0.99-1.06 (d, 3H), 1.18 (m, 1H), 1.29 (m, 1H), 1.61-1.71 (m, 1H), 1.83-2.08 (m, 3H), 2.21-2.28 (m, 1H), 2.62-2.73 (m, 1H), 3.06-3.13 (m, 1H), 3.47-3.53 (m, 2H), 4.36-4.43 (m, 1H), 6.98-7.06 (m, 2H), 7.22-7.26 (m, 2H)
