1: 4-(pyridin-4-yl)-1-chlorobutane With magnesium in tetrahydrofuran T=0°C; Inert atmosphere; 2: chloroformic acid ethyl ester With water in tetrahydrofuran 3 h; Inert atmosphere;

in tetrahydrofuran T=25°C; 0.5 h;

1: tetrahydrofuran / 8 h / -20 - 0 °C 2: tetrahydrofuran / 0.5 h / 20 - 25 °C 3: tetrahydrofuran / 0.5 h / 25 °C View Scheme