hydrogen; palladium dihydroxide in ethyl acetate T=20°C;

1: dimethyl piperidin-1,4-dicarboxylate With lithium diisopropyl amide in tetrahydrofuran; hexane 0.5 h; 2: carbon dioxide in tetrahydrofuran; hexane 0.25 h;

1.1: LDA / tetrahydrofuran / -78 °C 1.2: 94 percent / tetrahydrofuran / -78 - 20 °C 2.1: 99 percent / H2 / 20 percent Pd(OH)2/C / ethyl acetate / 20 °C View Scheme

1.1: 75 percent / sat. aq. NaHCO3 / tetrahydrofuran 2.1: 79 percent / NaI; K2CO3 / acetonitrile / 0 - 20 °C 3.1: LDA / tetrahydrofuran / -78 °C 3.2: 94 percent / tetrahydrofuran / -78 - 20 °C 4.1: 99 percent / H2 / 20 percent Pd(OH)2/C / ethyl acetate / 20 °C View Scheme

1.1: 79 percent / NaI; K2CO3 / acetonitrile / 0 - 20 °C 2.1: LDA / tetrahydrofuran / -78 °C 2.2: 94 percent / tetrahydrofuran / -78 - 20 °C 3.1: 99 percent / H2 / 20 percent Pd(OH)2/C / ethyl acetate / 20 °C View Scheme

thionyl chloride in dichloromethane T=20°C; 144 h;