To a solution of 6-chloro-5-(5,5-dimethyl-1,3,2-dioxaborinan-2-yl)-1H-indole (150 mg, 0.57 mmol) in dioxane (5 mL) and DMF (1 mL) was added N,N-dimethylformiminium chloride (155 mg, 1.21 mmol). The reaction mixture was stirred at room temperature for 20 min. 2N potassium carbonate (314 mg, 2.28 mmol), 3-(4-bromophenoxy)propanoic acid (139 mg, 0.57 mmol) and Pd(dppf)Cl2 (21 mg, 0.028 mmol) were then added. The reaction was degassed with N2 and heated to 90° C. for 30 min. The reaction was extracted with ethyl acetate (10 mL×2). The organic layers were washed with brine (10 mL), dried over sodium sulfate, and concentrated to give the title compound (170 mg, 87% yield) as a brown oil.
