1,2-Diiodoethane → tert-Butyl N-[7-iodo-2-methylthiopyrazolo[1,5-a]pyridin-3-yl]carbamate

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Reaction Steps

After dissolving tert-butyl N-[2-methylthiopyrazolo[1,5-a]pyridin-3-yl]carbamate (21.6 g) in tetrahydrofuran (1 L), a solution of n-butyllithium in hexane (1.6 M; 130 mL) was added dropwise at −78° C. under a nitrogen stream, and the mixture was stirred for 30 minutes. A solution of 1,2-diiodoethane (24 g) in tetrahydrofuran (50 mL) was added to the reaction mixture, and stirring was continued for 1 hour. Saturated aqueous ammonium chloride was added to the reaction mixture, the temperature was raised to room temperature, extraction was performed with ethyl acetate and the extract was washed with water and brine. After drying over anhydrous magnesium sulfate and filtration, the solvent was concentrated under reduced pressure, the residue was purified by silica gel column chromatography, and the title compound was obtained from the n-hexane:ethyl acetate (5:1) fraction as yellow crystals.

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