Iodine → (4-Iodo-pyridin-3-YL)-carbamic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of Example 17A (2.16 g, 11.12 mmol) in anhydrous tetrahydrofuran (50 mL) under N2 was cooled to −78° C. and treated dropwise with 1.7 M tert-butyl lithium in pentane (16.35 mL, 27.8 mmol). The mixture was stirred at −78° C. for 15 minutes, warmed to −30° C. and stirred for 2.5 hours. The dark brick-red solution was re-cooled to −78° C. and a solution of iodine (7.06 g, 27.8 mmol) in anhydrous tetrahydrofuran (18.5 mL) was added dropwise over 20 minutes to give a thick reaction mixture that was difficult to stir. The mixture was swirled at −78° C. for 15 minutes, warmed to −30° C., stirred for 40 minutes and warmed to 0° C. The mixture was quenched by addition of H2O (100 mL) and treated with solid Na2SO3 until a constant yellow color was achieved. The mixture was diluted with ethyl acetate and the layers were separated. The organic layer was washed with saturated sodium chloride solution, dried over anhydrous Na2SO4, filtered, and the filtrate was concentrated by rotary evaporation. Purification by chromatography on silica eluting with 10%-20% ethyl acetate in dichloromethane afforded the title compound as an amber oil which crystallized upon standing (2.32 g, 65%). MS (DCI+) m/z 321 (M+H)+.

Provenance & Evidence