1: 81 percent / NaH / tetrahydrofuran / 1 h / Heating 2: 91 percent / trifluoroacetic acid / CH2Cl2 / 7 h / 20 °C View Scheme

1: tert-Butyl (S)-5-oxo-2-pyrrolidinecarboxylate With sodium hydride in tetrahydrofuran T=20°C; 0.0833333 h; 2: benzyl bromide in tetrahydrofuran T=20°C; 0.5 h;

sodium hydride in tetrahydrofuran 1 h; Heating;

1.1: 4-(N,N-dimethlyamino)pyridine / acetonitrile / 48.58 h / 0 - 20 °C 2.1: lithium hexamethyldisilazane / tetrahydrofuran / 3 h / -78 °C / Inert atmosphere 2.2: 2.17 h / -78 °C / Inert atmosphere 3.1: lithium triethylborohydride / tetrahydrofuran / 0.5 h / -78 °C 3.2: 0.33 h / 0 °C 3.3: 2.5 h / -78 °C 4.1: trifluoroacetic acid / dichloromethane / 5 h / 20 °C 5.1: N-ethyl-N,N-diisopropylamine / 1,4-dioxane; acetonitrile / 24 h / 20 °C View Scheme