[Cl:1][C:2]1[N:7]=[CH:6][C:5]([NH:8][C:9](=[O:15])[O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[CH:4][CH:3]=1.[Li]CCCC.[I:21]I.O>C1COCC1>[Cl:1][C:2]1[N:7]=[CH:6][C:5]([NH:8][C:9](=[O:15])[O:10][C:11]([CH3:12])([CH3:14])[CH3:13])=[C:4]([I:21])[CH:3]=1
To the solution of tert-butyl (6-chloropyridin-3-yl)carbamate (160 g, 0.7 mol) in 1 L of anhydrous THF was added n-BuLi (600 mL, L5 ml) at −78° C. under N2 atmosphere. After the addition was finished, the solution was stirred at −78° C. for 30 min, and the solution of I2 (177.68 g, 0.7 mol) in 800 mL of anhydrous THF was added. Then the solution was stirred at −78° C. for 4 hrs, TLC indicated the reaction was over. Water was added for quench, and EtOAc was added to extract twice. The combined organic phases were washed with brine, dried over Na2SO4, filtered and purified by flash chromatography to afford 80 g of tert-butyl (6-chloro-4-iodopyridin-3-yl)carbamate as a yellow solid (32.3%).
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