Ammonium Hydroxide → 1-benzenesulfonyl-3-bromo-7-fluoro-1H-indole

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Reaction Steps

The suspension was then diluted with water (200 ml), extracted with tert-butyl methyl ether (3×100 ml) and the combined organic layers washed with water (3×100 ml), dried with sodium sulfate and concentrated in vacuo. The residue was purified by flash column chromatography eluting with 20% (v/v) ethyl acetate in isohexane to afford 1-benzenesulfonyl-7-fluoroindole as a colourless solid (3.96 g, 14.4 mmol). To a solution of 1-benzenesulfonyl-7-fluoroindole (2.0 g, 7.27 mmol) in dimethylformamide (10 ml) was added a solution of bromine (0.75 ml, 14.55 mmol) in dimethylformamide (25 ml) dropwise over 3 min. The mixture was then stirred at room temperature for 10 min and poured onto a mixture of sodium metabisulphite (2 g), ammonium hydroxide solution (3 ml), water (100 ml) and crushed ice (100 g). The resulting suspension was stirred until all colour had discharged and extracted into tert-butyl methyl ether (2×100 ml). The combined organic layers were washed with water (2×100 ml), dried with sodium sulfate and the solvent removed in vacuo to afford 1-benzenesulfonyl-3-bromo-7-fluoroindole as a salmon coloured solid (2.35 g, 6.64 mmol).

Provenance & Evidence