Benzenesulfonyl chloride → 1-benzenesulfonyl-5-bromo-2-methyl-1H-indole

Participants

Reaction Steps

To a solution of 5-bromo-2-methyl-1H-indole (1.5 g, 7.14 mmol) in 10 mL of DMF was added 60% sodium hydride in mineral oil (189 mg, 7.9 mmol). Once hydrogen gas evolution ceased, the mixture stirred for 10 minutes and was then treated with 1 mL (7.83 mmol) of benzene sulfonyl chloride. The reaction was monitored by TLC (ethyl acetate-hexanes (5:95)) to afford a major new slightly less polar product than starting material. After 2 hours, the mixture was poured into 50 mL of saturated aqueous ammonium chloride solution and extracted with three 50 mL portions of ethyl acetate. The combined organic layers were washed with four 25 mL portions of brine, dried over magnesium sulfate, treated with activated carbon (NORIT A™), filtered through diatomaceous earth, and concentrated in vacuo. The residue was adsorbed onto silica gel and chromatographed on silica gel using ethyl acetate-hexanes (1:99, then 2:98, then 3:97) to afford 1.71 g (68.4% yield) of 1-benzenesulfonyl-5-bromo-2-methyl-1H-indole as a clear oil.

Provenance & Evidence