Iodine → 3-Iodo-5-methoxy-1-methyl-1H-indole

Participants

Reaction Steps

5-Methoxy-1H-indole (5.15 g, 35.0 mmol) in DMF (100 mL) was stirred with KOH (2.06 g, 36.7 mmol) at room temperature for about 15 min then iodine (9.06 g, 35.7 mmol) was added. The mixture was stirred at room temperature for about 30 min followed by the portion-wise addition of NaH (60% dispersion in mineral oil, 1.67 g, 42.0 mmol). After stirring for about 15 min at room temperature, iodomethane (2.40 mL, 38.5 mmol) was added and the mixture was stirred for about 15 min. The solvents were removed under reduced pressure and the mixture was stirred with water (300 mL) for about 15 min. The slurry was treated with DCM (100 mL) and the layers were separated. The aqueous layer was extracted with DCM (30 mL) and the combined organic layers were washed with water (100 mL), dried over anhydrous MgSO4, filtered, and concentrated in vacuo to give crude 3-iodo-5-methoxy-1-methyl-1H-indole (9.90 g, 34.5 mmol, 99%) which was used directly. A round bottom flask was charged with 3-iodo-5-methoxy-1-methyl-1H-indole (9.90 g, 34.5 mmol), PdCl2(dppf)-CH2Cl2 adduct (1.408 g, 1.724 mmol), TEA (33.6 mL, 241 mmol), 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (28.7 g, 224 mmol) and 1,4-dioxane (200 mL). The reaction mixture was heated at about 100° C. for about 40 min, cooled to room temperature, and concentrated in vacuo. The material was stirred with EtOAc (300 mL), filtered, and the filter cake was washed with EtOAc (100 mL). The filtrate was concentrated in vacuo and the residue purified by silica gel chromatography (120 g column) eluting with 25% EtOAc in heptane to give 5-methoxy-1-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indole (3.70 g, 37%): LC/MS (Table 2, Method d) Rt=2.68 min; MS m/z: 288.2 (M+H)+.

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