Water → Ethyl 4,6-dichloro-3-formyl-1-[(4-methylphenyl)sulfonyl]-1H-indole-2-carboxylate

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Reaction Steps

Combine 3-formyl-2-carboethoxy-4,6-dichloroindole (46.3 g. 162 mmol) and anhydrous potassium carbonate (44.9 g, 325 mmol) in dimethylformamide (600 mL). Add p-toluenesulfonyl chloride (42.9 g, 225 mmol). After 18 hours, pour the reaction mixture into water (3 L) and stir to give a solid. Filter, rinse with water and diethyl ether, and recrystallize from acetonitrile/dichloroethane to give the title compound: mp 189°-191° C. (dec); Rf =0.64 (silica gel, 1/1 ether/hexane); 1H NMR (CDCl3) δ10.71 (s, 1H), 8.00 (m, 3H), 7.36 (m, 3H), 4.61 (q, 2H, J=7.2 Hz), 2.41 (s, 3H), 1.49 (t, 3H, J=7.1 Hz).

Provenance & Evidence