1: (4S)-4-benzyl-1,3-oxazolidine-2-thione With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 0.333333 h; 2: propionyl chloride in tetrahydrofuran; hexane T=-78 - 20°C;

triethylamine; lithium chloride in tetrahydrofuran T=-20 - 20°C; 3 h;

1.1: 95 percent / Et3N / CH2Cl2 / 0.5 h / 0 °C 2.1: n-BuLi / tetrahydrofuran; hexane / 0.33 h / -78 °C 2.2: 90 percent / tetrahydrofuran; hexane / -78 - 20 °C View Scheme

1.1: TiCl4; DIEA / CH2Cl2 / 0.33 h / 0 °C 1.2: CH2Cl2 / -78 - 0 °C 2.1: 90 percent / LiBH4 / diethyl ether; methanol View Scheme