CN(CCN(C)C)C.[Li]CCCC.[C:14]([O:18][C:19](=[O:28])[NH:20][C:21]1[CH:22]=[N:23][C:24]([Cl:27])=[CH:25][CH:26]=1)([CH3:17])([CH3:16])[CH3:15].[I:29]I>C1COCC1>[C:14]([O:18][C:19](=[O:28])[NH:20][C:21]1[CH:22]=[N:23][C:24]([Cl:27])=[CH:25][C:26]=1[I:29])([CH3:17])([CH3:15])[CH3:16]To a solution of TMEDA (25.4 g, 219.3 mmol) in dry THF (300 mL) was added dropwise n-BuLi (87.7 mL, 219.3 mmol) at −78° C., the mixture was stirred for 0.5 h at this temperature. A solution of (6-chloro-pyridin-3-yl)-carbamic acid tert-butyl ester (20 g, 87.7 mmol) in THF (170 mL) was added dropwise to the reaction mixture at −78° C. and the resulting mixture was continued to stir for 1 h at −78° C. Then a solution of I2 (26.7 g, 105.3 mmol) in dry THF (170 mL) was added dropwise at −78° C. After 1 h, the reaction was quenched with sat. aqueous NH4Cl (300 mL). The organic layer was separated and the aqueous phase was extracted with ethyl acetate (150 mL×3). The combined organic layers were dried over anhydrous Na2SO4 and concentrated under the reduced pressure. The residue was purified by column chromatography on silica gel (Petroleum ether/Ethyl acetate, 10/1) to give (6-chloro-4-iodo-pyridin-3-yl)-carbamic acid tert-butyl ester (7 g, 22.7%). 1H-NMR (CDCl3, 300 MHz) δ 8.95 (s, 1H), 7.73 (s, 1H), 6.64 (brs, 1H), 1.54 (s, 9H).
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