5-Iodoindole is an important organic intermediate. It can be used in agrochemical, pharmaceutical and dyestuff field. It is used as the starting material in the synthesis of 5-(α-fluorovinyl)-N-tosylindole.
The general procedure for the synthesis of 5-iodoindole from 5-bromoindole was as follows: CuI (9.6 mg, 0.0504 mmol, 5.0 mol%), 5-bromoindole (1.00 mmol if solid), and NaI (300 mg, 2.00 mmol) were added to a Schlenk tube, briefly evacuated and replaced three times with argon. Subsequently, N,N'-dimethyl-1,2-cyclohexanediamine (16 μL, 0.10 mmol, 10 mol%), 5-bromoindole (1.00 mmol if liquid) and dioxane (1.0 mL) were added under argon protection. The Schlenk tube was sealed with a polytetrafluoroethylene valve and the reaction mixture was stirred in an oil bath at 110°C for 22-23 hours. Upon completion of the reaction, the suspension was cooled to room temperature, diluted with 30% ammonia solution (5 mL), poured into water (20 mL) and extracted with dichloromethane (3 x 15 mL). The organic phases were combined, dried with anhydrous MgSO or NaSO and concentrated under reduced pressure, and the resulting crude product was purified by silica gel column chromatography to afford the target compound 5-iodoindole.
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