1: (S)-1-tert-butyl 2-ethyl 5-oxopyrrolidine-1,2-dicarboxylate With lithium hexamethyldisilazane in tetrahydrofuran T=-78°C; 1 h; 2: allyl bromide in tetrahydrofuran T=-78°C;

lithium hexamethyldisilazane in tetrahydrofuran T=-78°C; 1.) 1 h, 2.) 2 h; Product distribution;

1.1: sodium tetrahydroborate / methanol; water / 1 h / 20 °C 2.1: toluene-4-sulfonic acid / acetone / 1 h / -20 - 20 °C 3.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / dichloromethane / 16 h / 20 °C 4.1: dimethylsulfide borane complex / tetrahydrofuran / 5 h / Cooling with ice 4.2: 16 h / 20 °C 5.1: triethylamine / dichloromethane / 1 h / 0 - 20 °C 6.1: tetraethyl ammonium fluoride / tetrahydrofuran / 16 h / Reflux 7.1: water; acetic acid / 1.5 h / Heating 8.1: pyridine / dichloromethane / 16 h / 20 °C 9.1: sodium azide / N,N-dimethyl-formamide / 1.5 h / 80 °C / Inert atmosphere 10.1: lithium hexamethyldisilazane / tetrahydrofuran / 0.5 h / -78 °C 10.2: 12 h / -78 - 0 °C 11.1: palladium 10 on activated carbon; hydrogen / ethyl acetate / 2 h / 2068.65 Torr 12.1: triethylamine / dichloromethane / 0.08 h / 20 °C 13.1: triethylamine / dichloromethane 14.1: trifluoroacetic acid / dichloromethane / 0.5 h View Scheme

1.1: sodium tetrahydroborate / methanol; water / 1 h / 20 °C 2.1: toluene-4-sulfonic acid / acetone / 1 h / -20 - 20 °C 3.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / dichloromethane / 16 h / 20 °C 4.1: dimethylsulfide borane complex / tetrahydrofuran / 5 h / Cooling with ice 4.2: 16 h / 20 °C 5.1: triethylamine / dichloromethane / 1 h / 0 - 20 °C 6.1: tetraethyl ammonium fluoride / tetrahydrofuran / 16 h / Reflux 7.1: water; acetic acid / 1.5 h / Heating 8.1: pyridine / dichloromethane / 16 h / 20 °C 9.1: sodium azide / N,N-dimethyl-formamide / 1.5 h / 80 °C / Inert atmosphere View Scheme

1.1: sodium tetrahydroborate / methanol; water / 1 h / 20 °C 2.1: toluene-4-sulfonic acid / acetone / 1 h / -20 - 20 °C 3.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / dichloromethane / 16 h / 20 °C 4.1: dimethylsulfide borane complex / tetrahydrofuran / 5 h / Cooling with ice 4.2: 16 h / 20 °C 5.1: triethylamine / dichloromethane / 1 h / 0 - 20 °C 6.1: tetraethyl ammonium fluoride / tetrahydrofuran / 16 h / Reflux 7.1: water; acetic acid / 1.5 h / Heating 8.1: pyridine / dichloromethane / 16 h / 20 °C 9.1: sodium azide / N,N-dimethyl-formamide / 1.5 h / 80 °C / Inert atmosphere 10.1: lithium hexamethyldisilazane / tetrahydrofuran / 0.5 h / -78 °C 10.2: 12 h / -78 - 0 °C View Scheme

1.1: sodium tetrahydroborate / methanol; water / 1 h / 20 °C 2.1: toluene-4-sulfonic acid / acetone / 1 h / -20 - 20 °C 3.1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / dichloromethane / 16 h / 20 °C 4.1: dimethylsulfide borane complex / tetrahydrofuran / 5 h / Cooling with ice 4.2: 16 h / 20 °C 5.1: triethylamine / dichloromethane / 1 h / 0 - 20 °C 6.1: tetraethyl ammonium fluoride / tetrahydrofuran / 16 h / Reflux 7.1: water; acetic acid / 1.5 h / Heating 8.1: pyridine / dichloromethane / 16 h / 20 °C 9.1: sodium azide / N,N-dimethyl-formamide / 1.5 h / 80 °C / Inert atmosphere 10.1: lithium hexamethyldisilazane / tetrahydrofuran / 0.5 h / -78 °C 10.2: 12 h / -78 - 0 °C 11.1: palladium 10 on activated carbon; hydrogen / ethyl acetate / 2 h / 2068.65 Torr View Scheme