1: 6-ethoxy-piperidin-2-one With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 1 h; 2: p-toluenesulfonyl chloride in tetrahydrofuran; hexane T=-78 - 20°C; 19 h;

1.1: 72 percent / NaBH4; HCl in EtOH / 7 h / 0 °C 2.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C 2.2: 53 percent / tetrahydrofuran; hexane / 19 h / -78 - 20 °C View Scheme