A mixture of 6-chloro-5-(5,5-dimethyl-1,3,2-dioxaborinan-2-yl)-1H-indole (100 mg, 0.38 mmol) and N,N-dimethylformiminium chloride (97 mg, 0.76 mmol) in DMF (3 mL) and dioxane (0.6 mL) was stirred at room temperature for 30 min. Potassium carbonate (2 mL, 4 mmol, 2 N) was added to the mixture. Then 2-(4-bromo-2-fluorophenoxy)ethanol (89 mg, 0.38 mmol) and Pd(dppf)Cl2 (20 mg, 0.03 mmol) was added to the reaction. The mixture was degassed by passing nitrogen through the solution for 5 min. and stirred at 80° C. for 2 hrs. The reaction was cooled and concentrated. The residue was dissolved with EtOAc (100 mL), washed with water (30 mL), saturated ammonium chloride (30 mL), brine (30 mL), dried over sodium sulfate and concentrated to afford a crude product. The crude was further purified by silica gel chromatography (PE/EtOAc=20% to 50%) to give the title compound (40 mg, 30% yield) as a light yellow oil. 1H NMR (400 MHz, CD3OD) δ 9.89 (s, 1H), 8.17 (s, 1H), 8.11 (s, 1H), 7.62 (s, 1H), 7.20 (m, 3H), 4.18 (t, 2H), 3.93 (t, 2H).
