1: With lithium diisopropyl amide in tetrahydrofuran; hexane T=-75°C; 2 h; 2: With water; silica gel in hexane; dichloromethane

1.1: 2,2,6,6-tetramethylpiperidine; butyllithium / tetrahydrofuran; hexane / 2 h / -75 °C 1.2: 76 percent / iodine / tetrahydrofuran 2.1: 79 percent / butyllithium; diisopropylamine / tetrahydrofuran; hexane / 4 h / -75 °C 3.1: isopropylmagnesium chloride / tetrahydrofuran / 1 h / 0 °C 3.2: 67 percent / N-chlorosuccinimide / tetrahydrofuran / 1 h / 25 °C 4.1: diisopropylamine; butyllithium / tetrahydrofuran; hexane / 2 h / -75 °C 4.2: 81 percent / iodine / tetrahydrofuran 5.1: lithium diisopropylamide / tetrahydrofuran; hexane / 2 h / -75 °C 5.2: 26 percent / silica gel; H2O / CH2Cl2; hexane View Scheme

1.1: diisopropylamine; butyllithium / tetrahydrofuran; hexane / 2 h / -75 °C 1.2: 81 percent / iodine / tetrahydrofuran 2.1: lithium diisopropylamide / tetrahydrofuran; hexane / 2 h / -75 °C 2.2: 26 percent / silica gel; H2O / CH2Cl2; hexane View Scheme

1.1: isopropylmagnesium chloride / tetrahydrofuran / 1 h / 0 °C 1.2: 67 percent / N-chlorosuccinimide / tetrahydrofuran / 1 h / 25 °C 2.1: diisopropylamine; butyllithium / tetrahydrofuran; hexane / 2 h / -75 °C 2.2: 81 percent / iodine / tetrahydrofuran 3.1: lithium diisopropylamide / tetrahydrofuran; hexane / 2 h / -75 °C 3.2: 26 percent / silica gel; H2O / CH2Cl2; hexane View Scheme

1.1: 79 percent / butyllithium; diisopropylamine / tetrahydrofuran; hexane / 4 h / -75 °C 2.1: isopropylmagnesium chloride / tetrahydrofuran / 1 h / 0 °C 2.2: 67 percent / N-chlorosuccinimide / tetrahydrofuran / 1 h / 25 °C 3.1: diisopropylamine; butyllithium / tetrahydrofuran; hexane / 2 h / -75 °C 3.2: 81 percent / iodine / tetrahydrofuran 4.1: lithium diisopropylamide / tetrahydrofuran; hexane / 2 h / -75 °C 4.2: 26 percent / silica gel; H2O / CH2Cl2; hexane View Scheme

1: 2,4-dichloro-5-iodopyridine With tert.-butyl lithium in diethyl ether; pentane T=-75°C; 0.25 h; 2: carbon dioxide T=-78°C;