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Method A: Ethyl 5-fluoroindole-2-carboxylate (1.0 eq.) was mixed with a DMF solution (5 mL) of KOH (4.0 eq.) at room temperature and stirred until a homogeneous suspension was formed. Subsequently, DMF solution (3 mL) of iodine (1.0 eq.) was added slowly and dropwise. The reaction mixture was stirred at room temperature for 1.5 hours. Upon completion of the reaction, the mixture was poured into a mixture consisting of saturated aqueous NaHSO3 solution (15 mL), 30% NH4OH (2 mL) and water (15 mL). The resulting solid product was collected by filtration and dried under reduced pressure, and the resulting ethyl 5-fluoro-3-iodo-1H-indole-2-carboxylate was used for subsequent reactions without further purification.

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