Reaction Steps
To a stirred solution of 4-allyldimethylsilylphenylacetic acid (2 Scheme 8, 5.7 g, 24.3 mmol) in THF (400 mL) at −78° C. was added triethylamine (4.4 mL, 31.5 mmol) followed by pivaloyl chloride (3.4 mL, 28 mmol). The mixture was stirred for 15 min at −78° C. and 1 h at room temperature and then re-cooled to −78° C. In a separate flask, (4S)-4-benzyl-2-oxazolidinone (5.2 g, 29.0 mmol) was dissolved in 20 mL of THF and cooled to −78° C. To this solution was added n-BuLi (2.5 M in hexanes, 11.6 mL, 29.0 mmol) via syringe and the solution was stirred for 30 min at −78° C. The metalated oxazolidinone was added via cannula to the white slurry prepared as described above and stirred for 30 min −78° C., then allowed to room temperature over 2 h. After quenching the reaction with 1 N aqueous sodium sulfate (100 mL) and evaporation of volatiles in vacuo, the residue was extracted with ethyl acetate (50×2 mL), dried (Na2SO4), and concentrated. The resulting oil was purified by column chromatography (1:5 ethyl acetate/hexanes) to afford a colorless oil (5.7 g, 54%); 1H NMR (300 MHz, CDCl3) δ 0.37 (s, 6 H), 1.85 (d, J=8.01 Hz, 2 H), 2.85 (dd, J=13.40, 9.30 Hz, 1 H), 3.32 (dd, J=13.40, 3.27 Hz, 1 H), 4.21 (d, J=5.28 Hz, 2 H), 4.34 (d, J=15.80 Hz, 1 H), 4.43 (d, J=15.80 Hz, 1 H), 4.74 (m, 1 H), 4.92 (m, 1 H), 4.98 (m, 1 H), 5.87 (ddt, J=16.92, 10.11, 8.10 Hz, 1 H), 7.19-7.22 (2 H), 7.29-7.38 (3 H), 7.43 (d, J=7.74 Hz, 2 H), 7.60 (d, J=7.74 Hz, 2 H); 13C NMR (75 MHz, CDCl3) −3.3 (2C), 23.8, 37.8, 41.7, 55.4, 66.2, 113.6, 127.4, 129.0 (2C), 129.3 (2C), 129.6 (2C), 134.1 (2C), 134.4, 134.7, 135.3, 153.5, 171.2; HRMS calcd for C23H27N1O3Si 393.1760, found 393.1755.
