Benzenesulfonyl chloride → 1-benzenesulfonyl-3-bromo-6-nitro-1H-indole

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Reaction Steps

Add triethyl amine (Et3N) (6.7 mL, 48 mmol, 4 eq) and DMAP (240 mg, 2.0 mmol, 0.1 eq) to a slurry of 3-bromo-6-nitro indole, 2 (4.82 g, 20 mmol) in 100 mL of CH2Cl2. Let the solution stir until the 3-bromo-6-nitro indole dissolves and then add benzenesulfonyl chloride (3.1 mL, 24 mmol, 1.2 eq). Let the solution stir overnight. Filter off the precipitate, which forms, wash the precipitate with CH2Cl2, and collect the filtrates to give 6.83 g of the title compound. Sequentially wash the combined filtrates with 1 M HCl, saturated sodium bicarbonate, and brine. Dry the organic layer over Na2SO4, filter, and then concentrate the filtrate. Boil the resulting solid in ˜30 mL of CH2Cl2 and a little MeOH, add 30 mL hexanes, let cool, and then filter off the precipitate to give another 1.3 g of the title compound. 1H NMR (DMSO-d6) δ 8.74 (d, 1H, J=2.2 Hz), 8.58 (s, 1H), 8.19 (dd, 1H, J=2.2, 8.8 Hz), 8.08-8.05 (m, 2H), 7.75-7.68 (m, 2H), 7.63-7.59 (m, 2H)—.

Provenance & Evidence