1: N-tert-butoxycarbonyl-α-cyanopyrrolidine With lithium diisopropyl amide in tetrahydrofuran T=-78°C; 0.75 h; 2: 1-bromo-2-chloro-ethane in tetrahydrofuran T=-78 - 20°C; Further stages.;

1.1: 85 percent / trifluoroacetic anhydride; triethylamine / CH2Cl2 / 0 - 20 °C 2.1: lithium diisopropylamide / tetrahydrofuran / 0.75 h / -78 °C 2.2: 55 percent / tetrahydrofuran / -78 - 20 °C View Scheme

1.1: isopropyl chloroformate; triethylamine / CH2Cl2 / 0.5 h / -30 - -20 °C 1.2: 60 percent / aq. NH3 / CH2Cl2 / -30 - 20 °C 2.1: 85 percent / trifluoroacetic anhydride; triethylamine / CH2Cl2 / 0 - 20 °C 3.1: lithium diisopropylamide / tetrahydrofuran / 0.75 h / -78 °C 3.2: 55 percent / tetrahydrofuran / -78 - 20 °C View Scheme