(Diethylamino)sulfur trifluoride → 5-Fluoro-4-iodoindolin-2-one

Participants

Reaction Conditions

Reaction Steps

A suspension of 1,3-dihydro-1-hydroxy-4-iodo-2H-indol-2-one (2.43 g, 9 mmol) (prepared according to Kende et al., Synth. Commun. 20(14, 2133-2138 (1990)) in dry dichloromethane (500 mL) was cooled to −25° C. under an argon atmosphere with magnetic stirring. A solution of diethylaminosulfur trifluoride (DAST, 1.35 mL) (Aldrich) in dry dichloromethane (40 mL) was added dropwise at such a rate that the reaction temperature did not rise above −25° C. (about 15 min.) After stirring for an additional 30 min. at −25° C., the reaction was quenched by the addition of saturated aqueous sodium bicarbonate solution (180 mL) and allowed to warm to room temperature. The mixture was then filtered through Celite® (Fisher) and the layers separated. The aqueous layer was extracted with dichloromethane (2×300 mL). The dichloromethane layers were washed with saturated aqueous sodium chloride solution (200 mL), combined, dried (magnesium sulfate) and concentrated. The resulting residue was purified by flash chromatography on silics gel using ethyl acetate—dichloromethane (1:7, V/V) as solvent to give 1,3-dihydro-5-fluoro-4-iodo-2H-indol-2-one (Yield 1.08 g, 43%).

Provenance & Evidence