To a 1.6 M solution of n-BuLi in hexane (12.1 mL, 19.3 mmol) is added dropwise a solution of (S)-(−)-4-benzyl-2-oxazolidinone (3.26 g, 18.4 mmol) in dry THF (80 mL) at −71.6° C. under nitrogen over 10 minutes. The solution is warmed up to −60.5° C. while the addition, and allowed to stir for 1 hour in dry ice/MeOH bath. 3-(Biphenyl-4-yl)propanoyl chloride (intermediate 13: 5.46 g, 22.31 mmol) in dry THF (20 mL) is added dropwise at −72° C. over 5 minutes. The solution is warmed up to −56.5° C. while the addition. After stirring 10 minutes at the same temperature, the reaction mixture is allowed to warm to room temperature and stirring is continued for 3 hours. The reaction mixture is filtered, and the collected precipitate is washed with 20 mL (10 mL×2) of MeOH and then with 150 mL of H2O to give the desired product (4.26 g). The products in the mother liquor is extracted with ethyl acetate, washed with brine, dried over MgSO4, filtered, and concentrated under reduced pressure. The obtained residue is suspended in 80 mL of MeOH, and the suspension is filtered and washed with 20 mL of MeOH (1.79 g). The two fractions are mixed to give (S)-4-benzyl-3-(3-(biphenyl-4-yl)propanoyl)oxazolidin-2-one (6.05 g, 85% in 2 steps). Retention time=1.77 minutes (condition A); MS (m+1)=387.3; 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 2.77 (dd, J=13.39, 9.35 Hz, 1 H) 2.99-3.15 (m, 2 H) 3.20-3.43 (m, 3 H) 4.09-4.24 (m, 2 H), 4.68 (dddd, J=9.76, 6.73, 3.47, 3.28 Hz, 1 H) 7.18 (d, J=7.07 Hz, 2 H) 7.23-7.37 (m, 6 H) 7.42 (t, J=7.58 Hz, 2 H) 7.53 (d, J=8.1 Hz, 2 H), 7.57 (d, J=7.8 Hz, 2 H).
