2-Chloro-4-iodopyridine

78607-36-0

153034-86-7

General procedure for the synthesis of 2-chloro-4-iodopyridine from 2-chloro-3-iodopyridine: 2-chloro-3-iodopyridine (12 g, 50 mmol) was prepared as a solution by dissolving it in 20 mL of tetrahydrofuran (THF). The solution was slowly added to a pre-prepared lithium diisopropylammonium solution at -78°C (the lithium diisopropylammonium solution was prepared by reacting 1.6 M n-butyllithium hexane solution (31.25 mL, 50 mmol) with diisopropylamine (7 mL, 50 mmol) in 100 mL THF). After 3 hours of reaction, the reaction was quenched by adding 20 mL of water to the reaction mixture, followed by extraction with ether (2 x 100 mL). The organic layers were combined, dried with magnesium sulfate, filtered and concentrated under vacuum at 20 °C to give a brown solid. Purification by silica gel column chromatography (eluent: ethyl acetate/heptane=8/2) gave light yellow needle-like crystals in 95% yield (11.4 g). The structure of the product was analyzed by 1H NMR (CDCl3): δ 8.07 (d, J = 5.3 Hz, 1H), 7.76 (d, J = 1.1 Hz, 1H), 7.59 (dd, J = 5.0/0.11 Hz, 1H); 13C NMR (CDCl3): δ 151.7, 149.6, 133.0, 131.5, 106.6; MS ( EI) m/z 240 (M + 1) confirmed.