Iodine → Tert-butyl (2-chloro-3-iodopyridin-4-YL)carbamate

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tert-Butyllithium (36.3 mL, 1.7M in pentane) is added dropwise to a solution of (2-chloro-pyridin-4-yl)-carbamic acid tert-butyl ester (6.00 g, 26.2 mmol) in THF (46 mL) at −78° C. under Ar. The yellow/orange mixture is stirred for 2 h at −78° C. then warmed to −40° C. for 1 h then cooled to −78° C. before dropwise addition of I2 (15.65 g, 61.7 mmol) in THF (49 mL). The reaction mixture is stirred for 1.5 h at −78° C. then at −10° C. for 30 minutes. The reaction is quenched with saturated NH4Cl solution then diluted with CH2Cl2 and washed with saturated NH4Cl, saturated sodium thiosulfate, water then brine. The organic layer is dried over MgSO4, filtered and concentrated to dryness. The crude product is chromatographed eluting with 1-2% MeOH/CH2Cl2 to yield the title product (7.96 g, 22.5 mmol) as a bright yellow solid. 1H NMR (CDCl3, 300 MHz) δ8.14 (d, 1H), 8.02 (d, 1H), 7.32 (bs, 1H), 1.60 (s, 9H). EI MS [M]+=354, 356, Cl pattern.

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