Phosphorus oxychloride → ethyl 5-bromo-3-formyl-1H-indole-2-carboxylate

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Reaction Steps

In a 1 L round bottom flask 10.5 mL of phosphorus oxychloride was added to 15.5 g of N-methylformanilide at room temperature that resulted in a yellow solid after 15 min. At this time, 170 mL of 1,2-dichloroethane and 20.1 g of ethyl 5-bromoindole-2-carboxylate were added. The resulting suspension was heated under reflux for 4 hours and then concentrated to remove the organic solvent. 75 g of sodium acetate in 750 mL of water were added and the solid suspension was stirred for 30 min at room temperature, filtered and washed 3 times with water. The crude material was dried under vacuum for 1 hour and swished with 500 mL of EtOH to yield 21.2 g of the title compound as off-white solid.

Provenance & Evidence